Investigating system and method for the in-situ detection of properties within a solidified powder material

Abstract

An investigating system (200) for the in-situ detection of properties (114, 116) within a powder material (104) solidified by means of a high-energy beam (128), comprising an eddy-current-based investigating unit (202), which can be arranged on a movement unit (110) and is arranged and designed to detect a material property of solidified powder material (104) by means of an eddy-current investigation, and so differences in conductivity within the solidified powder material (104) can be detected in order to identify properties (114, 116) during the additive manufacturing, wherein the investigating unit (202) comprises a first eddy-current sensor unit (210), which is arranged and designed to identify a property with a first property size greater than or equal to a size limit value, in particular a single defect, and wherein the investigating unit (202) comprises a second eddy-current sensor unit (230), which is arranged and designed to identify a collection of properties with a second property size smaller than the size limit value, in particular a porous area of defects.

Description

[0001] Test system and method for in-situ detection of properties within a solidified powder material

[0002] The invention relates to a testing system and a method for in-situ detection of properties within a solidified powder material as well as a manufacturing system.

[0003] Test systems for the in-situ detection of properties within a solidified powder material are generally known. In the additive manufacturing of

[0004] Components made of powder material are solidified to produce the component layer by layer. The powder material can be solidified, for example, using a high-energy beam, particularly a laser beam, or a binder.

[0005] Thermography methods can be used to detect defects, for example, but the data volume is so large that real-time analysis is either impossible or only possible to a limited extent. Furthermore, repeatable tests are not possible. Furthermore, particles in the beam path distort the results. Another disadvantage of thermography methods is that the required test setup is comparatively expensive.

[0006] It is also possible to test solidified powder material using ultrasound. A disadvantage of ultrasonic methods is that the achievable test resolution is usually insufficient. Furthermore, ultrasonic testing probes can only be positioned below the base plate, so limited accessibility must be considered.

[0007] Computed tomography (CT) techniques can usually be used to precisely identify defects, but these techniques cannot be used in situ and are also comparatively expensive. Furthermore, radiation protection is required during testing.

[0008] Defects can usually be detected using acoustic emission analysis, but determining the exact location of the defect is only possible to a limited extent. Furthermore, repeat testing is generally not possible. Optical methods also cannot detect hidden defects.

[0009] US 2016 / 9215 A1 discloses a system for the non-destructive testing of additively manufactured components using an electromagnetic field. Eddy current testing is performed, but a setup is proposed that offers such limited spatial resolution that precise detection of differently shaped defects in a solidified powder material is not possible.

[0010] DE 10 2016 201 290 A1 , DE 10 2011 111 818 A1 , EP 3 632 595 A 1 and US 2018 / 0264590 A1 disclose devices for the additive manufacturing of components with testing units.

[0011] Industry demands the use of additive manufacturing processes with low scrap rates and high quality, among other things, to reduce downstream testing effort. In particular, computed tomography, which is currently widely used, for example, for components in medical technology or aerospace engineering, leads to high costs and / or a significant time commitment. Furthermore, there is a requirement to raise process stability in additive manufacturing to a level comparable to conventional manufacturing, as additive manufacturing offers particular advantages in terms of resource utilization.

[0012] It is therefore an object of the invention to provide a testing system and a method for the in-situ detection of properties within a solidified powder material, as well as a manufacturing system, that reduce or eliminate one or more of the aforementioned disadvantages. In particular, it is an object of the invention to provide a solution that enables reliable in-situ detection of properties in a solidified powder material.

[0013] This object is achieved with a testing system and a method according to the features of the independent patent claims. Further advantageous embodiments of these aspects are specified in the respective dependent patent claims. The features disclosed in the patent claims, the description, and the drawings can be combined individually in any technologically expedient manner, with further embodiments of the invention being shown.

[0014] According to a first aspect, the object mentioned at the outset is achieved by a testing system for the in-situ detection of properties within a solidified powder material, comprising an eddy current-based testing unit that can be arranged on a movement unit and is arranged and designed to detect an electromagnetic material property of solidified powder material by means of an eddy current test, so that conductivity differences within the solidified powder material can be detected in order to identify properties, wherein the testing unit comprises a first eddy current sensor unit that is arranged and designed to identify a property with a first property size greater than or equal to a size limit, in particular a single defect, and wherein the testing unit comprises a second eddy current sensor unit that is arranged and designed,to identify a collection of properties with a second property size smaller than the size threshold, in particular a porous,

[0015] Defect area.

[0016] The invention is based on the finding that individual defects and clusters of micro-defects are the most common causes of rejects in powder-based additive manufacturing. Furthermore, the invention is based on the finding that different eddy current-based mechanisms are required to test the aforementioned properties to ensure reliable identification. This finding can be utilized to technical advantage by using two different eddy current sensor units, namely the first and second eddy current sensor units, which are designed to identify properties with different property sizes.

[0017] The inspection system thus enables in-situ adaptation, particularly correction, of the identified properties, as explained in more detail below. Furthermore, a build order or a component can be aborted during production after a property is identified, thus stopping the costly additive manufacturing process after the creation of a property that cannot be adapted or corrected. Furthermore, the inspection system offers the advantage of eliminating the need for complex inspection steps after the component's completion, which typically incur high costs with computed tomography.

[0018] A further advantage of the eddy current-based process is that the amount of data generated is so small that data analysis can take place during additive manufacturing, allowing real-time process control based on the results of the inspection system. Furthermore, properties can be assigned layer by layer. Furthermore, in-situ recording of properties allows a correlation to be derived between the property and the process parameters used, as well as process states detected by sensors in the production system, so that the additive manufacturing process can be optimized. This can be achieved, for example, using artificial intelligence. Furthermore, the process can be controlled in-situ, as explained in more detail below. Furthermore, process interruptions and terminations are reduced by increasing process stability.Furthermore, such testing enables digital production documentation.

[0019] The testing system is designed for the in-situ detection of properties within a solidified powder material. A solidified powder material is understood to be any powder material whose powder particles are bonded to one another at least in sections. A solidified powder material can, for example, be formed by joined and / or glued powder particles. The powder material to be solidified is, in particular, electrically conductive and / or ferromagnetic. In-situ testing and detection of properties is understood to mean, in particular, testing during the production of the component from the powder material, for example, layer by layer, once or multiple times between the production of a first layer and the production of a final layer of the component.

[0020] Properties are generally understood to mean all properties within the solidified powder material. A property can be, for example, an inhomogeneity or anomaly. For example, a property can be a cavity, e.g., due to incomplete melting, a gas pore, microporosity, a material property, delamination, a geometric deviation, a reduced surface quality, discoloration, and / or properties in the material structure. Furthermore, a property can be a geometry, a component edge, or a contour of the solidified powder material or the component.

[0021] The testing system is designed in particular for powder-bed-based additive manufacturing processes. The testing system is particularly suitable for an additive layered construction process, for example, for selective laser beam melting (L-PBF), selective electron beam melting (E-PBF), or metal binder jetting (MBJ). The powder material can be solidified, for example, with a high-energy beam and / or a binder. The high-energy beam is preferably a laser or electron beam. A solidified powder material is understood in particular to be a powder material whose powder particles are at least partially bonded to one another, in particular fused to one another.

[0022] The testing system includes the eddy current-based testing unit. An eddy current-based testing unit is generally understood to be a testing unit that is arranged and configured to detect a property based on an eddy current test. The testing unit is preferably arranged and configured to generate an alternating magnetic field that penetrates a surface to be tested, generates an eddy current within the material, and measures the feedback of this eddy current, using it for material testing.

[0023] The generated eddy current acts counter to the generator current through its own magnetic field, allowing these differences to be detected by the testing unit. In particular, the eddy current-based testing unit can detect differences in the electromagnetic properties within the solidified powder material. For example, a pore exhibits a different electrical conductivity than the solidified powder material surrounding it. A detected difference in electrical conductivity can thus be used to infer a property.

[0024] When the testing system is used as intended, the testing unit can, for example, induce an eddy current into the solidified powder material. The reaction of this eddy current is then measured. Furthermore, changes in the eddy current can be detected, and based on this, conductivity differences can be identified. A corresponding evaluation of the detected conductivity differences, in turn, allows conclusions to be drawn about properties, particularly defects. As an alternative to the testing unit that induces the eddy current, an additional excitation unit can also be provided.

[0025] The testing unit can be arranged on a movement unit. This means, in particular, that the testing unit is designed to be arranged on a movement unit that is to be moved over a powder bed.

[0026] The eddy current-based testing unit is arranged and configured to detect an electromagnetic material property of solidified powder material using an eddy current test. Thus, conductivity differences within the solidified powder material can be detected to identify properties. It is particularly preferred that changes in the electromagnetic material property be detected.

[0027] The testing unit comprises the first eddy current sensor unit. The eddy current sensor unit is arranged and designed, particularly during intended operation, to identify a property with a first property size greater than or equal to a size limit. The first eddy current sensor unit is arranged and designed, in particular, to detect an individual defect, such as a single pore. The first eddy current sensor unit is preferably arranged and designed to measure a magnetic field at the eddy current sensor unit that is influenced by the course of the eddy currents in the solidified powder material. An eddy current path in the solidified powder material that is disturbed by a property leads to a measuring effect at the location of the sensor. In particular, the first eddy current sensor unit is designed to identify larger properties.Therefore, the first eddy current sensor unit is designed to identify those properties that are greater than or equal to the size threshold. It is preferred that the first eddy current sensor unit be miniaturizable. Preferably, the first eddy current sensor unit comprises one, two, or more eddy current sensors.

[0028] The test unit further comprises the second eddy current sensor unit. The second eddy current sensor unit is arranged and configured to identify a collection of properties. A collection of properties can, for example, be porosity, which is formed, for example, by micropores. The second eddy current sensor unit is preferably configured to measure an impedance of an eddy current coil in order to detect a change in the impedance caused by a counter field of the eddy currents. The second eddy current sensor unit preferably has an integrating behavior, so that defect regions can advantageously be identified. The second eddy current sensor unit is preferably miniaturizable. The second eddy current sensor unit preferably comprises one, two, or more eddy current sensors.The test unit, the first eddy current sensor unit, and / or the second eddy current sensor unit is / are preferably configured to generate property signals representing a property. A signal is understood to be any type of information carrier. The property signal can be configured, for example, as a data set. The property signal is preferably provided permanently, so that a change in the property signal allows a conclusion to be drawn about a property.

[0029] In particular, a signal strength, preferably a constant signal strength, can be used to determine the properties of the solidified powder material. An offset in the signal strength can characterize a reduction in the material density. To maximize this value, parameter variations can be performed to achieve an optimum, in particular, maximizing the density of the component.

[0030] Furthermore, the test unit, the first eddy current sensor unit, and / or the second eddy current sensor unit are preferably configured to provide the property signals to a control device. The control device, as explained in more detail below, is preferably configured to identify and classify properties. Based on this, properties can be adapted, in particular corrected, if technically possible, as is possible with the adaptation signal explained in more detail below.

[0031] The first eddy current sensor unit and the second eddy current sensor units comprise, in particular, individual sensors which are arranged and designed to generate and provide test signals on the basis of which conductivity differences can be detected, so that the electromagnetic material properties can be detected.

[0032] It is preferred that sensor data from the first eddy current sensor unit and the second eddy current sensor unit can be evaluated in combination to enable improved detection of properties based on the combined evaluation. This is preferably carried out by superimposing the sensor data and / or merging the data, thereby expanding the testing capability of the testing system. It is preferred that the first eddy current sensor unit has a first control unit and / or the second eddy current sensor unit has a second control unit and / or the testing system has a control device that is / are configured to detect conductivity differences within the solidified powder material and to identify properties based on test signals from the first eddy current sensor unit and / or the second eddy current sensor unit.It is preferred that the first control unit and / or the second control unit and / or the control device are configured to generate and / or provide a property signal representing the identified property.

[0033] A preferred development of the testing system is characterized in that the first eddy current sensor unit and / or the second eddy current sensor unit are arranged and designed to effect a sensor movement in a secondary direction, wherein the secondary direction is not aligned parallel to a main direction, in particular a feed direction, of the movement unit. It is preferred that the first eddy current sensor unit and / or the second eddy current sensor unit is arranged to be movable in the secondary direction. Alternatively or additionally, individual sensors of the first eddy current sensor unit and / or the second eddy current sensor unit can be arranged to be movable in the secondary direction. For example, a magnetic field sensor of the first eddy current sensor unit can be moved back and forth laterally during the test by a drive, in particular a linear motor, so that a zigzag movement is generated during the test.This would, for example, improve geometric inspection. The technical effect of the secondary movement is, among other things, to reduce the directional dependence of the resolution and improve the resolution.

[0034] It is preferred that the first eddy current sensor unit comprises excitation elements arranged in multiple rows, for example excitation wires, which are arranged in such a way that excitation currents aligned at an angle to one another can be effected with them in order to improve the identification of properties.

[0035] In a preferred embodiment of the test system, it is provided that the first eddy current sensor unit has a first test resolution and the second eddy current sensor unit has a second test resolution, wherein the first test resolution is higher, in particular many times higher, than the second test resolution.

[0036] The first and second test resolutions are understood to be a measure of the level of detail of the test performed with the first eddy current sensor unit and the second eddy current sensor unit. The higher the test resolution of the eddy current sensor units, the more precisely the test can be performed and the smaller the identifiable characteristics can be. Furthermore, a test resolution can be understood as a maximum measurement point spacing.

[0037] It is preferred that the first inspection resolution be less than 100 micrometers. Furthermore, it may be preferred that the second inspection resolution be less than 1 millimeter.

[0038] A further preferred development of the testing system is characterized in that the size limit is between 15 micrometers and 100 micrometers, in particular between 20 micrometers and 50 micrometers. It has been found that a selection of a first eddy current sensor unit and a second eddy current sensor unit, which are differentiated by this size limit and / or their spatial testing resolution, is particularly advantageous for detecting the different properties in solidified powder material.

[0039] In a further preferred embodiment of the test system, the first eddy current sensor unit is or comprises a magnetic field sensor. Preferably, the first eddy current sensor unit comprises a plurality of magnetic field sensors. The magnetic field sensors can be arranged as an array. The magnetic field sensor can be, for example, a magnetoresistive sensor, a GMR (giant magnetic resistance) sensor, a TMR (tunneling magnetic resistance) sensor, and / or a Hall sensor. It is preferred that the magnetic field sensor be miniaturizable.

[0040] Furthermore, it may be preferred that the second eddy current sensor unit is or comprises an eddy current coil. The eddy current coil may, for example, be a printed coil. It is further preferred that the second eddy current sensor unit has two or more eddy current coils. It is preferred that the eddy current coils are also used as an excitation unit in the second eddy current sensor unit.

[0041] In particular, the combination of magnetic field sensors and eddy current coils advantageously enables the identification of large properties and smaller properties in the form of a collection of micro defects.

[0042] It is preferred that the magnetic field sensors be arranged at a distance from the eddy current coils, so that the eddy current coils have no or only a minor physical influence on the magnetic field sensors. Furthermore, the influence of the eddy current coils on the magnetic field sensors can be influenced by additional elements.

[0043] In a further preferred embodiment, the testing unit is arranged and configured to detect the electromagnetic material property by means of eddy current testing during solidification, in particular during exposure and / or during standstill and / or during movement of the movement unit. The testing unit can, for example, be arranged upstream or downstream of the movement unit in the feed direction. The movement unit can, for example, be a coating unit.

[0044] A further preferred development of the testing system is characterized in that it comprises a control device or the control device which is signal-coupled to the testing unit and which is configured to generate an adaptation signal, in particular a correction signal, based on an identified property, in particular an individual defect and / or a porous defect region, which represents an adaptation strategy, in particular a correction strategy, of the production system for adapting, in particular for eliminating, the property.

[0045] The adaptation signal is understood to be any type of information carrier suitable for initiating the adaptation strategy of the manufacturing system. The adaptation signal can, for example, be embodied as a data set and / or represent a command. Furthermore, the adaptation signal can be based on an identification and / or classification of the property, in particular the individual defect and / or the defect area.

[0046] Furthermore, it is preferred that the control device is configured to optimize parameters of the manufacturing system based on the identified properties and / or based on the adaptation signal, so that the generation of properties is reduced or avoided.

[0047] The control device is preferably configured such that the adjustment signal causes an adjustment of production and / or machine parameters and / or process conditions. For example, the adjustment signal can cause process parameters such as scanner, exposure, binding, and coating parameters, gas flow, preheating, and / or build chamber pressure to be adjusted.

[0048] Furthermore, the adjustment signal can cause a new exposure and / or obstruction, in particular an adjusted exposure and / or obstruction, of properties. The adjustment signal can also cause a change in the scanning strategy and / or a scanning pattern, a change in an exposure sequence, a change in the temporal sequence of the exposure, a new powder application, an adjustment of the build platform lift or the layer thickness. Furthermore, the adjustment signal can represent or cause the abort of individual components or an entire build job.

[0049] The testing system thus enables the adaptation, in particular the correction, of a property of the currently generated layer, whereas existing approaches generally only allow the property to be influenced through further, already generated layers. This enables a more direct and targeted influence on the properties. Furthermore, the testing system not only enables the identification of defects or the testing of the component's integrity and a status assessment of the material properties within the test depth, but also enables the targeted derivation of measures for the active elimination of defects and the subsequent verification of whether the elimination was successful. This is where the repeatability of the test comes into play. No other in-situ testing system enables direct testing, derivation of measures, as well as targeted healing and verification of this healing.

[0050] In a preferred development of the inspection system, the control device is configured to control the inspection unit such that a predefined number of layers, in particular at predefined layer positions, are inspected. A testing system configured in this way makes it possible, for example, for layers 50 to 500 of a build job to be inspected, while the remaining layers are not inspected due to their irrelevance to component quality. This can be the case, for example, if the first layers are intended to connect the component to a build platform and their properties are therefore irrelevant. This further reduces the amount of data generated.

[0051] A preferred embodiment of the testing system is characterized in that the testing unit is arranged and configured to identify a property adapted based on the adaptation signal. Furthermore, it may be preferred that the control device is configured to generate a second adaptation signal based on the identified adapted property, which represents a second adaptation strategy of the manufacturing system for further adapting the adapted property.

[0052] In a further preferred embodiment of the testing system, it is provided that it comprises an excitation unit for causing the eddy current in the solidified powder material, wherein in normal operation one excitation unit is arranged next to or two excitation units are arranged on both sides of the first eddy current sensor unit at the same distance from the test surface.

[0053] This arrangement enables a particularly small spacing of the eddy current sensor units from the test surface, in particular a powder bed surface, thus advantageously enabling eddy current testing. The excitation unit is preferably arranged and configured to generate the eddy current such that it has a penetration depth of greater than 100 micrometers, preferably more than 200 micrometers. During normal operation, the eddy current sensor units are located between the powder bed and the excitation unit and / or in the same plane as the excitation unit, parallel to the surface of the powder bed.

[0054] In a further preferred embodiment of the testing system, it is provided that this comprises a topography measuring system for determining a topography of the solidified powder material, in particular a surface of the solidified powder material, which is configured to generate a topography signal characterizing a topography image that represents a distance of the solidified powder material to the testing unit, wherein the property is further identified based on the topography image.

[0055] The topography measurement system can be, for example, a unit for fringe light projection, a line scanner, and / or a light field camera. The distance between the solidified powder material and the inspection unit is determined, in particular, between the surface of the solidified powder material and the first and / or second eddy current sensor unit, in particular their individual sensors.

[0056] A further preferred embodiment of the testing system is characterized in that the first eddy current sensor unit and the second eddy current sensor unit are arranged offset from one another. For example, they can have a pitch or spacing. Furthermore, they can be arranged in multiple rows. It is particularly preferred that the first eddy current sensor unit and the second eddy current sensor unit are arranged horizontally offset from one another during normal operation. In particular, the individual sensors of the second eddy current sensor unit are arranged offset from one another. During normal operation, the individual sensors can be arranged offset from one another orthogonally to a main movement direction, in particular in the feed direction, of the movement unit.

[0057] In a further preferred embodiment of the testing system, the first eddy current sensor unit and / or the second eddy current sensor unit comprise individual sensors, in particular the magnetic field sensors and / or eddy current coils, arranged and configured in such a way that they can be supplemented by at least one additional individual sensor. With such an arrangement and configuration of the eddy current sensor units, they can be individually expanded, thus addressing various additive manufacturing requirements.

[0058] In a further preferred embodiment, it is provided that the test system has an application-specific integrated circuit which is signal-coupled to the test unit and which is configured to amplify, digitize, filter and / or provide signals received by the first eddy current measuring unit and / or the second eddy current measuring unit for further processing.

[0059] An advantage of the application-specific integrated circuit is its high integration density, so that it requires only a small amount of space and the test unit can be miniaturized.

[0060] In a further preferred embodiment of the testing system, the control device is configured to identify a component edge and / or a contour of the component, in particular of the solidified powder material, based on output signals from the first and / or second eddy current sensor unit. The detection of component edges and contours is advantageously possible with the testing system because loose powder material acts like an insulator during the measurements of the first and / or second eddy current sensor unit. Intelligent superposition and processing of both signals is therefore possible.

[0061] According to a further aspect, the object mentioned at the outset is achieved by a manufacturing system for the additive production of a component by means of solidification of a powder material, comprising a construction chamber in which the powder material can be arranged, a solidification unit which is arranged and designed to solidify the powder material, in particular with a high-energy beam or a binder, a movement unit arranged such that it can be moved above the powder material to be solidified, and a testing system according to one of the embodiments described above, wherein the testing unit is arranged on the movement unit.

[0062] The manufacturing system can preferably be controlled using the control device of the inspection system described above. Alternatively, the manufacturing system can have a control unit that receives and / or generates the adjustment signal mentioned above, and the manufacturing system can be controlled using the adjustment signal. The manufacturing system can be controlled or regulated in parallel with the process using the inspection system described above, so that the detected properties of the currently produced layer and / or one of the previously produced layers are adjusted, in particular corrected, or a component or a construction order is aborted.

[0063] The solidification unit is preferably designed as an exposure unit for exposing the powder material. Alternatively or additionally, the solidification unit is designed for applying a binder.

[0064] In a preferred embodiment of the production system, the movement unit is a coating unit for forming a powder bed surface. The coating unit has, for example, a smoothing function to form a flat powder bed surface. This function can be implemented, for example, with a coating lip. Furthermore, the coating unit can have a powder material supply or be coupled to a powder material reservoir such that the powder material can be fed to the coating unit. The arrangement of the testing unit on the coating unit has the advantage that the coating unit regularly moves over the powder bed, thus enabling complete, process-parallel testing of the solidified powder material. Particularly with unidirectional layer application, it is preferred that the testing unit performs a first test on an outward path and a second test on a return path to a starting position.

[0065] In a further preferred embodiment, the movement unit is designed as at least one handling system, in particular a robot, for example, with at least one robot arm. The handling system is preferably arranged and configured to inspect those sections that are accessible while the powder material is still solidifying. The inspection process could be partially or entirely parallel to the solidification process. Furthermore, it is preferred that the movement unit is or comprises the solidification unit.According to a further aspect, the object mentioned at the outset is achieved by a method for the in-situ detection of properties within a solidified powder material, in particular with a testing system according to one of the embodiments described above, comprising the steps of: detecting an electromagnetic material property of solidified powder material by means of an eddy current test, so that conductivity differences within the solidified powder material are detected in order to identify properties, wherein a first eddy current sensor unit is used to identify a property with a first property size greater than or equal to a size limit, in particular a single defect, and wherein a second eddy current sensor unit is used to identify a collection of properties with a second property size smaller than the size limit, in particular a porous defect region.

[0066] It is preferred that test signals be generated on the basis of which conductivity differences are detected, so that the electromagnetic material property is detected. The detection of the material property is preferably carried out using a first control unit of the first eddy current sensor unit and / or a second control unit of the second eddy current sensor unit and / or a control device. Furthermore, the identification of the property is preferably carried out using the first control unit and / or the second control unit and / or the control device.

[0067] According to a preferred embodiment of the method, this comprises the steps of: generating an adaptation signal, in particular a correction signal, based on an identified property, in particular a single defect and / or a porous defect region, wherein the adaptation signal, in particular the correction signal, represents an adaptation strategy, in particular a correction strategy, of a manufacturing system for adapting the property, and controlling the manufacturing system with the adaptation signal, in particular the correction signal, in order to adapt the property.

[0068] For further advantages, design variants and details of the individual aspects and their possible further training, please refer to the description of the other aspects, the corresponding features and further training.

[0069] Preferred embodiments are explained using the accompanying figures. They show:

[0070] Figure 1 : a schematic, two-dimensional view of an exemplary

[0071] Embodiment of a manufacturing system;

[0072] Figure 2: a schematic, two-dimensional plan view of the manufacturing system shown in Figure 1;

[0073] Figure 3: another schematic, two-dimensional view of an exemplary embodiment of a manufacturing system;

[0074] Figure 4: another schematic, two-dimensional view of an exemplary embodiment of a manufacturing system;

[0075] Figure 5: a schematic, two-dimensional view of an exemplary

[0076] Embodiment of a first eddy current sensor unit;

[0077] Figure 6: a schematic, two-dimensional view of an exemplary

[0078] Embodiment of a connection between a magnetic field sensor and an application-specific integrated circuit;

[0079] Figure 7: a schematic, two-dimensional view of an exemplary

[0080] Embodiment of a second eddy current sensor unit;

[0081] Figure 8: a schematic view of an exemplary method; and

[0082] Figure 9: a schematic view of another exemplary

[0083] procedure.

[0084] In the figures, identical or essentially functionally identical or similar elements are designated by the same reference numerals.

[0085] Figures 1 to 3 show a manufacturing system 100 for the additive production of a component 102 by illuminating a powder material 104. The component 102 is formed from solidified powder material 104. The powder material 104 is solidified using a high-energy beam 128. The high-energy beam 128 can be a laser beam, for example. The component 102 is created in the powder bed 106. For this purpose, powder material 104 is applied layer by layer using the movement unit 110, designed as a coater 112. The thickness of the layer of powder material 104 can be in the micrometer or millimeter range. The movement unit 110 is moved in the feed direction 118.

[0086] After a layer of powder material 104 has been applied, it is selectively exposed with the exposure unit 108 and thereby typically melted. Subsequently, the table 124 moves vertically downward by one layer thickness using the adjustment unit 126, and a new layer of powder material 104 can be created with the coater 112. The system is arranged on a frame 122.

[0087] By exposing the powder material 104 to the high-energy beam 128, properties 114 and 116 are also regularly created. Property 114 is represented as a single defect, and property 116 is represented as a porous defect area with a multitude of micro-defects. This process takes place in the build chamber 107.

[0088] Figure 3 shows that a mirror element 120, which may, for example, be part of a scanner, is arranged in the beam path of the high-energy beam 128. Using the mirror 120, the high-energy beam 128 can be directed to any position on the test surface, which is formed as a powder bed surface 130.

[0089] The manufacturing system 100 further includes the testing system 200. The testing system 200 is configured for in-situ detection of the properties 114, 116 within the solidified powder material 102. The testing system 200 includes an eddy current-based testing unit 202 arranged on the movement unit 110. The testing unit 202 is arranged and configured to detect an electromagnetic material property of the solidified powder material 102 using an eddy current test, so that conductivity differences within the solidified powder material 102 can be detected in order to identify the properties 114, 116 during additive manufacturing. The eddy current 204 is generated by the testing system 200 using an excitation unit 242 or an excitation unit not included in the testing system 200.

[0090] The inspection unit 202 comprises a first eddy current sensor unit 210, which is arranged and configured to identify a property 114 with a first property size greater than or equal to a size threshold, in particular a single defect. Furthermore, the inspection unit 202 comprises a second eddy current sensor unit 230, which is arranged and configured to identify a collection of properties 116 with a second property size less than the size threshold, in particular a porous defect region.

[0091] The test system 200 further comprises a control device 240 which is signal-coupled to the test unit 202 and which is configured to generate a correction signal based on an identified property 114, 116, which represents a correction strategy of the manufacturing system 100 for correcting the property 114, 116.

[0092] The inspection system 200 further includes a topography measurement system 244 for determining a topography of the solidified powder material 104. The topography measurement system 244 is configured to generate a topography image representing a distance of the powder bed surface 130 from the inspection unit 202, wherein the property 114, 116 is further identified based on the topography image. The arrangement of the topography measurement system 244 on the coater 112 is optional, as it can also be arranged such that it can capture the topography across the entire build plane, for example, from obliquely above the build plane.

[0093] Figure 4 shows a manufacturing system 100 constructed essentially analogously to Figure 3, wherein the solidification unit is designed as a binder unit 246 for applying a binder 248. Thus, a powder material 104 solidified using a metal binder jetting process can be tested using the testing system 200 described above.

[0094] Figure 5 shows that the first eddy current sensor unit 210 comprises a plurality of magnetic field sensors 212. The magnetic field sensors 212 are connected in pairs to application-specific integrated circuits 214. This connection is shown in particular in Figure 6, wherein these connections are formed by means of connecting surfaces 222 and connecting wires 224.

[0095] The application-specific integrated circuits 214 are further connected to an FPGA 216, a control element 218, and a memory element 220. The FPGA 216 can be used, for example, for pre-analysis and buffering of the data generated by the magnetic field sensors 212 and for specifying a test frequency. The FPGA acts as an interface converter between the ASICs and other units of the system.

[0096] The control element 218 is further coupled to a computing unit 206 by means of a data connection 207.

[0097] Figure 7 shows the second eddy current sensor unit 230 in detail. The second eddy current sensor unit 230 is constructed analogously to the first eddy current sensor unit 210. The second eddy current sensor unit 230 comprises an eddy current coil 232, shown only schematically, which in turn is coupled to an FPGA 234, a control element 236, and a memory element 238. The second eddy current sensor unit 230 preferably has several, preferably a plurality of, eddy current coils 232.

[0098] Figure 8 shows a method for the in-situ detection of properties 114, 116 within a powder material 102 solidified by means of a high-energy beam 128. The method comprises step 300: detecting an electromagnetic material property of the solidified powder material 102 using an eddy current test, such that conductivity differences within the solidified powder material 102 are detected in order to identify properties 114, 116 during additive manufacturing. A first eddy current sensor unit 210 identifies a property with a first property size, and a second eddy current sensor unit 230 identifies a collection of properties. In step 302, the property 114 and / or the collection of properties 116 is detected based on the detected electromagnetic material property.

[0099] Figure 9 shows a preferred embodiment of the method described above. In step 304, a correction signal is generated based on the identified property 114, 116, in particular a single defect and / or a porous defect region, wherein the correction signal represents a correction strategy of a manufacturing system 100 for correcting the property 114, 116. In step 306, the manufacturing system 100 is controlled with the correction signal to correct the property 114, 116.

[0100] The inspection system 200 described above and the corresponding method enable particularly advantageous detection of properties 114, 116 in a component produced from powder material 104. In particular, different property variables can be reliably identified. Furthermore, the inspection system and the method enable process-parallel control or regulation of an additive manufacturing process, since the amount of data generated and required is so small that real-time control is possible.

[0101] REFERENCE SYMBOL

[0102] manufacturing system

[0103] component

[0104] Powder material

[0105] powder bed

[0106] Construction Chamber

[0107] exposure unit

[0108] movement unit

[0109] Coater

[0110] Characteristics

[0111] Characteristics

[0112] Coater feed

[0113] Mirror element

[0114] frame

[0115] Table

[0116] Adjustment unit high-energy beam

[0117] Powder bed surface

[0118] Test system eddy current-based test unit

[0119] Eddy current

[0120] Computing unit

[0121] Data connection first eddy current sensor unit 212 magnetic field sensor

[0122] 214 ASIC (application-specific integrated circuit)

[0123] 216 FPGA (field-programmable logic gate array)

[0124] 218 Control element 220 Memory element

[0125] 222 connecting surfaces

[0126] 224 connecting wires

[0127] 230 second eddy current sensor unit

[0128] 232 Eddy current coil 234 FPGA

[0129] 236 Control

[0130] 238 storage element

[0131] 240 Control device

[0132] 242 Excitation unit 244 Topography measuring system

[0133] 246 binder unit

[0134] 248 Binders

Claims

CLAIMS 1. A testing system (200) for the in-situ detection of properties (114, 116) within a solidified powder material (104), comprising an eddy current-based testing unit (202) that can be arranged on a movement unit (110) and is arranged and designed to detect an electromagnetic material property of solidified powder material (104) by means of an eddy current test, such that conductivity differences within the solidified powder material (104) can be detected in order to identify properties (114, 116), wherein the testing unit (202) comprises a first eddy current sensor unit (210) that is arranged and designed to identify a property with a first property size greater than or equal to a size threshold, and wherein the testing unit (202) comprises a second eddy current sensor unit (230) that is arranged and designed to identify a collection of properties with a second property size smaller than the size threshold.

2. Test system (200) according to claim 1, wherein the first eddy current sensor unit (210) has a first test resolution and the second eddy current sensor unit (230) has a second test resolution, wherein the first test resolution is higher, in particular many times higher, than the second test resolution.

3. Test system (200) according to one of the preceding claims, wherein the size limit is between 15 pm and 100 pm, in particular between 20 pm and 50 pm.

4. Test system (200) according to one of the preceding claims, wherein the first eddy current sensor unit (210) is or comprises a magnetic field sensor (212), and / or the second eddy current sensor unit (230) is or comprises an eddy current coil (232). Testing system (200) according to one of the preceding claims, wherein the testing unit (202) is arranged and configured to detect the electromagnetic material property by means of eddy current testing during solidification, in particular during exposure and / or standstill and / or movement of the movement unit (110). Testing system (200) according to one of the preceding claims, comprising a control device (240) signal-coupled to the testing unit (202) and configured to generate an adaptation signal based on an identified property, in particular an individual defect and / or a porous defect region, which represents an adaptation strategy of the manufacturing system for adapting the property.Testing system (200) according to one of the preceding claims, wherein the testing unit is arranged and configured to identify a property adjusted on the basis of the adjustment signal, and / or the control device (240) is configured to generate a second adjustment signal based on the identified adjusted property, said second adjustment signal representing a second adjustment strategy of the manufacturing system for further adjusting the adjusted property. Testing system (200) according to one of the preceding claims, comprising an excitation unit (242) for causing the eddy current in the solidified powder material (104), wherein, during normal operation, the first eddy current sensor unit (210) and / or the second eddy current sensor unit (230) is / are arranged between the excitation unit (242) and a test surface (130). Testing system (200) according to one of the preceding claims, comprising a topography measuring system for determining a topography of the solidified powder material (104), which is configured to generate a topography signal characterizing a topography image that represents a distance of the solidified powder material (104) from the testing unit (202), wherein the property is further identified based on the topography image. Testing system (200) according to one of the preceding claims, wherein the first eddy current sensor unit (210) and the second eddy current sensor unit (230) are arranged offset from one another. Testing system (200) according to one of the preceding claims, wherein the first eddy current sensor unit (210) and / or the second eddy current sensor unit (230) have individual sensors arranged and configured such that they can be supplemented by at least one further individual sensor.Testing system (200) according to one of the preceding claims, comprising an application-specific integrated circuit (214) which is signal-coupled to the testing unit (202) and which is configured to amplify, digitize, filter, and / or provide signals received from the first eddy current testing unit and / or the second eddy current testing unit for further processing. Testing system (200) according to one of the preceding claims, wherein the control device (240) is configured to identify a component edge of the component based on output signals from the first and / or second eddy current sensor unit (210). Manufacturing system (100) for the additive production of a component by solidifying a powder material (104), comprising a build chamber (107) in which the powder material (104) can be arranged. a solidification unit (108, 146) arranged and configured to solidify the powder material (104), a movement unit (110) arranged to be movable above the powder material to be solidified, and a testing system (200) according to any one of the preceding claims 1-13, wherein the testing unit (202) is arranged on the movement unit (110). The manufacturing system (100) according to the preceding claim 14, wherein the movement unit (110) is a coating unit (112) for forming a powder bed surface. A method for the in-situ detection of properties (114, 116) within a solidified powder material (104), in particular with a testing system according to any one of the preceding claims 1-13, comprising the steps: Detecting an electromagnetic material property of solidified powder material (104) by means of an eddy current test, so that conductivity differences within the solidified powder material (104) are detected in order to identify properties (114, 116), wherein a first eddy current sensor unit (210) identifies a property (114, 116) with a first property size greater than or equal to a size threshold, in particular a single defect, and wherein a second eddy current sensor unit (230) identifies a collection of properties with a second property size less than the size threshold, in particular a porous defect region. The method according to the preceding claim 16, comprising the steps: Generating an adjustment signal based on an identified property, in particular a single defect and / or a porous defect region, wherein the adjustment signal is a adaptation strategy of a manufacturing system to adapt the property, and Controlling the manufacturing system with the adjustment signal to adjust the property.

Images