Method and device and system for calibrating manufacturing equipment

Abstract

The invention relates to a method for calibrating a manufacturing system. The manufacturing apparatus is configured to perform additive manufacturing of a three-dimensional workpiece by layer-by-layer solidification of a raw material by means of position-selective irradiation. The method comprises estimating at least one property of the illumination point or / and the illumination pattern to be provided using a plurality of measurement results of optical measurements performed in a time offset manner, each measurement result specifying at least one property of the illumination point or / and the illumination pattern at a respective measurement time. The method further includes calibrating the manufacturing apparatus based on the estimated at least one attribute. The invention also relates to a device and a system.

Description

Technical Field

[0001] The present invention relates to an apparatus for calibrating a manufacturing equipment, a method for calibrating such a manufacturing equipment, and a system for additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer. Background Technology

[0002] Three-dimensional workpieces can be produced layer by layer by the curing of continuous material layers, creating a series of cured layers connected together. Such methods vary particularly depending on the type of material used and / or the curing properties of the material used to produce the workpiece.

[0003] An example of this layer-based additive manufacturing method is powder bed curing. In this method, a raw material layer (e.g., a layer of powder, metal, and / or ceramic raw material) is processed to form a three-dimensional workpiece. For this purpose, a raw material powder layer is applied to a build platform or carrier, and the powder layer is selectively cured at specific locations according to the desired geometry of the workpiece to be produced. For location-selective curing, the powder layer can be irradiated, for example, using laser radiation or an electron beam. The radiation impacting the powder layer causes the powder particles to be heated and thus melted or sintered. After the desired area of ​​the powder layer has been cured, additional successive layers of raw material powder are then applied and selectively cured at specific locations until the workpiece has the desired shape and size. Selective laser melting or laser sintering can be used, for example, to produce prototypes, tools, replacement parts, or medical prostheses, such as dental or orthopedic prostheses, based on CAD data.

[0004] Unlike powder bed curing, other additive manufacturing methods do not involve curing the material layer by layer by means of position-selective irradiation. Therefore, for example, uncured material can be fed to a printhead, which applies the material onto a carrier, where it is cured.

[0005] An important parameter in additive layer construction methods is the quality of the produced workpiece. Therefore, the object of the present invention is, for example, to improve the quality of workpieces produced using additive manufacturing equipment suitable for additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer. Summary of the Invention

[0006] According to a first aspect of this disclosure, an apparatus is provided for calibrating manufacturing equipment, wherein the manufacturing equipment is adapted to perform additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer.

[0007] For example, the manufacturing equipment is configured for powder bed curing and includes an irradiation system for providing irradiation points and / or irradiation patterns. For example, the irradiation system is adapted to selectively irradiate the raw material to cure it. The manufacturing equipment may be adapted to perform additive manufacturing by means of powder bed melting and / or sintering. For example, the irradiation system includes one or more irradiation sources, such as one or more lasers. The irradiation system may be adapted to provide laser irradiation points and / or laser irradiation patterns, for example, in the build area of ​​the manufacturing equipment, such as on a layer of raw material powder. For example, the irradiation system is adapted to provide one or more beams that form laser irradiation points and / or laser irradiation patterns upon impacting a surface (e.g., the surface of a powder layer).

[0008] Manufacturing equipment may include one or more sensors configured to acquire condition data. The condition data may indicate the conditions of the manufacturing equipment or / or changes in the conditions of the manufacturing equipment.

[0009] A condition may correspond to a manufacturing operation or a specific portion of a manufacturing operation performed by manufacturing equipment. A condition may correspond to a planned interruption in the process during which irradiation is not performed. For example, such an interruption may be used for cleaning operations of manufacturing equipment (e.g., process gas filters) or to ensure predetermined process parameters (e.g., protective gas flow and / or temperature). However, a condition may also correspond to an unplanned interruption in the process. For example, such an interruption may be caused by a disruption in the manufacturing process performed by the manufacturing equipment. The manufacturing equipment may include a powder layer monitoring device adapted to detect such a disruption in the event of incorrect application of a powder layer or the application of a powder layer incorrectly.

[0010] It is conceivable that conditional data indicates changes in irradiation operations, changes in process gas atmosphere, coating operations using raw materials, and / or changes in the position of the build platform of the manufacturing equipment. Irradiation operations can be defined by the orientation and / or direction of travel of the illumination vector, wherein the illumination vector is positioned and illuminates the powder layer. For example, such sensors include optical sensors (e.g., photodetectors and cameras), gas pressure sensors, gas sensors for detecting the composition of gas mixtures, position sensors, motion sensors, and temperature sensors.

[0011] Manufacturing equipment may include a signal interface through which such conditional data is transmitted to a control unit. It is also conceivable that the conditional data is provided by a closed-loop control unit of the manufacturing equipment, which controls the components of the manufacturing equipment.

[0012] Manufacturing equipment may include optical sensors, such as spatially resolved optical sensors, or cameras. For example, the optical sensor is adapted to detect radiation in a spatially resolved manner, which (a) is emitted by an irradiation system and reflected by a surface (e.g., the surface of an irradiated powder layer), (b) is emitted by the irradiation system and scattered at the surface (e.g., the surface of an irradiated powder layer), (c) includes thermally induced thermal radiation caused by radiation emitted by the irradiation system impacting the surface (e.g., the powder layer surface), and / or (d) includes process radiation, such as that originating from a molten pool caused by radiation emitted by the irradiation system impacting the surface (e.g., the powder layer surface). For example, the optical sensor is configured such that it is sensitive to radiation falling within a predetermined wavelength range. A predetermined wavelength range can be selected, such that the predetermined wavelength range includes radiation of one or more wavelengths, wherein the radiation (i) may be emitted by the irradiation system, (ii) may be emitted by the irradiation system and reflected by a surface (e.g., the surface of the irradiated powder layer), (iii) may be emitted by the irradiation system and scattered at the surface (e.g., the surface of the irradiated powder layer), (iv) may include thermally induced thermal radiation caused by radiation emitted by the irradiation system impacting the surface (e.g., the powder layer surface), and / or (v) may include process radiation, such as that originating from a molten pool caused by radiation emitted by the irradiation system impacting the surface (e.g., the powder layer surface). For example, an optical sensor is adapted to detect an irradiation point (e.g., located on the powder layer) and / or an irradiation pattern provided by the irradiation system. For this purpose, the optical sensor may be configured and arranged such that the optical sensor is capable of recording an image of a portion or the entire powder layer, the image depicting the irradiation point and / or the irradiation pattern. At least one property of the provided irradiation point and / or irradiation pattern can be detected by the optical sensor. The optical sensor may be controlled by a control unit that controls the irradiation system. The sensor may be configured as part of the irradiation system.

[0013] Manufacturing equipment, such as an irradiation system, may include lenses, such as dynamic lenses. The lenses may be configured such that the focus provided by the lens is controllable (e.g., adjustable via electronic control signals). The lenses may be liquid lenses, such as focus-adjustable liquid lenses. The lenses may be associated with optical sensors. For example, the lenses are arranged such that the optical sensor can detect, through the lens, an irradiation point (e.g., located on a powder layer) and / or an irradiation pattern provided by the irradiation system. In other words, the lenses may be arranged in the optical path between the optical sensor and the build area and / or the powder layer. For example, the optical sensor can record images through the lenses. The lenses can be adjusted and / or controlled such that the focus of the optical sensor is located in the processing plane, for example, on the surface of the powder layer currently to be irradiated.

[0014] Instead of a single optical sensor, it is also conceivable to provide multiple optical sensors, each configured as described above. In this case, multiple lenses can also be provided, each lens associated with a different optical sensor.

[0015] The manufacturing apparatus may also include at least one reference element. The at least one reference element may be arranged such that it is located outside the powder layer and / or outside the build area and / or outside the processing plane. The at least one reference element may be mounted at a previously known location. This previously known location may be fixed relative to the surface of the powder layer to be irradiated. An optical sensor may be adapted to record an image depicting one or more of the at least one reference element. It is conceivable that such an image may further include a depiction of the provided irradiation point and / or irradiation pattern.

[0016] For example, the manufacturing apparatus includes a first deflection unit. Alternatively or additionally, the manufacturing apparatus may include a second deflection unit and / or a third deflection unit. In each case, such a deflection unit may include (e.g., a 2-axis) scanning system comprising one or more mirrors movable in a controllable manner. The deflection units may be configured such that they can be oriented to a common (e.g., overlapping) processing area. Thus, an energy beam can be directed into the processing area and / or the field of view of an associated optical sensor can be directed into the processing area via each deflection unit. The processing area may include a processing plane, such as at least a portion or local surface of a powder layer.

[0017] In a first variation, the optical sensor is configured such that it always detects the same portion and / or the same spatial region of the powder layer. In this variation, the optical sensor can be configured to directly receive radiation from the powder layer, i.e., without directing the radiation to the optical sensor via one of the deflection units. In a second variation, a first deflection unit is associated with the optical sensor. The first deflection unit can be configured to controllably define the field of view of the optical sensor, for example, the image recording area of ​​the sensor relative to the powder layer and / or a reference element. This allows control over the field of view of the optical sensor such that the irradiated point and / or the irradiated pattern and / or the reference element or one or more reference elements are visible in the recorded image. In this variation, the optical sensor receives radiation from the powder layer indirectly, i.e., only after the radiation has been directed to the optical sensor via the first deflection unit.

[0018] The optical sensor can be arranged off-axis relative to the light beam provided for irradiating the powder layer. When multiple light beams are provided, the optical sensor can be arranged off-axis relative to all of the multiple light beams or only relative to a first portion of the multiple light beams. In the latter case, it is conceivable that the optical sensor is arranged on the axis of a second portion of the multiple light beams (coaxial with the second portion of the light beam). For example, the optical sensor can be arranged off-axis relative to a light beam that can be provided by a second deflection unit or a third deflection unit, and optionally, the optical sensor can be arranged on the axis of a light beam that can be provided by a first deflection unit.

[0019] At least one attribute of the provided irradiation point and / or irradiation pattern can be detected by an optical sensor, such as through a first deflection unit. Similarly, the position of the reference element can be detected by an optical sensor, such as based on an image thus recorded having a depiction of the reference element. It is also conceivable that the first deflection unit is adapted to position the irradiation point and / or irradiation pattern on the powder bed. In this case, the irradiation source can be associated with the first deflection unit, which can be said to perform a dual function.

[0020] The corresponding irradiation point and / or irradiation pattern, detectable by an optical sensor (e.g., via the first deflection unit), can be located using the second deflection unit. In other words, the second deflection unit can be configured to define the direction along which the (laser) radiation is output in the direction of the powder layer. The second deflection unit can be configured to generate a corresponding irradiation pattern by intentionally changing the position where the radiation strikes the powder layer, and this irradiation pattern can be depicted in an image recorded by the optical sensor. Alternatively, it is conceivable that the irradiation pattern points towards the second deflection unit, and the second deflection unit only defines the position of the irradiation pattern on the powder layer.

[0021] The third deflection unit can be configured in the same manner as the second deflection unit. For example, different energy beams, such as corresponding laser beams, can be supplied to the second and third deflection units, which can be provided by the laser source of the irradiation system. It is conceivable that the corresponding irradiation point and / or irradiation pattern can be located using either the second or third deflection unit. It is also possible to simultaneously provide the corresponding irradiation point and / or irradiation pattern using both the second and third deflection units, or / and have the corresponding irradiation point and / or irradiation pattern depicted by an optical sensor.

[0022] The manufacturing equipment may further include deflection units configured accordingly to allow for the manufacture of workpieces by simultaneously irradiating them with multiple energies or laser beams. As mentioned above, it is conceivable that the manufacturing equipment includes not just one optical sensor, but multiple optical sensors. In this case, each optical sensor may be associated with a different deflection unit within the deflection unit, and the provided irradiation point and / or irradiation pattern can be detected by the deflection unit associated with the corresponding sensor (e.g., by a deflection unit not associated with the corresponding sensor). A corresponding optical sensor may be provided to one, two, three, or even each deflection unit, and optionally, a corresponding lens may be provided to one, two, three, or even each deflection unit.

[0023] The device includes a control unit for controlling the irradiation system.

[0024] The control unit is adapted to estimate at least one attribute of the irradiation point and / or irradiation pattern to be provided based on multiple measurement results of optical measurements performed in a time-shifted manner (e.g., by means of an optical sensor), wherein each measurement result indicates at least one attribute of the irradiation point and / or irradiation pattern at a corresponding measurement time. The control unit is also adapted to calibrate the additive manufacturing equipment based on the estimated at least one attribute. For example, the control unit is adapted to perform the method according to the third aspect described below.

[0025] The control unit may be adapted to receive conditional data and / or control optical sensors, for example, to record one or more images. The control unit may be adapted to control deflection units, for example, to define or / and adjust the position of the illumination point and / or illumination pattern provided by the controlled deflection unit. The control unit may also be adapted to control deflection units to define or / and adjust the field of view of the optical sensors associated with the controlled deflection unit / these controlled deflection units. The control unit may also be adapted to control lenses, for example, to adjust the focal point of the lens. The control unit may be adapted to control the illumination system and / or other components of the manufacturing equipment.

[0026] According to a second aspect of this disclosure, a system is provided. The system includes the apparatus according to the first aspect and manufacturing equipment.

[0027] According to a third aspect of this disclosure, a method is provided for calibrating manufacturing equipment adapted to perform additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer. For example, the method is performed by an apparatus according to the first aspect, such as a control unit. The apparatus, control unit, and / or manufacturing equipment and its components may be configured as described above with respect to the first aspect.

[0028] The method includes estimating at least one attribute of an illumination point and / or illumination pattern to be provided based on multiple measurement results of optical measurements performed in a time-shifted manner. Each measurement result indicates at least one attribute of the illumination point and / or illumination pattern at a corresponding measurement time. Because multiple measurement results are used, an accurate and reliable estimation of at least one attribute is ensured compared to a scheme that considers only a single measurement.

[0029] Estimation can be performed using computational neural networks (CNNs). The estimation can be based on algorithms trained by machine learning.

[0030] At least one optical measurement in an optical measurement may include a recorded image, wherein an illumination point and / or illumination pattern at the time the image was recorded is depicted in the image. It is conceivable that images be recorded at different measurement times. These images may be recorded by an optical sensor, in a first variation by directly imaging the radiation reflected by the powder bed, or according to a second variation by imaging the radiation reflected by the powder bed and directed towards the optical sensor through a first deflection unit. When multiple optical sensors are present, it is conceivable that images be recorded by different optical sensors at different times, and that this series of images be used as a measurement performed in a time-shifted manner (e.g., a portion of a measurement).

[0031] Typically, an irradiation point can be understood as a point on a surface struck by an energy beam, such as a point in a processing plane irradiated by a laser beam. An irradiation point is usually formed by exactly one energy beam. Thermally induced radiation reflected, scattered, or emitted at the irradiation point, or radiation emitted by the molten pool located at the irradiation point, can be detected by an optical sensor. An irradiation pattern can be understood as a pattern composed of multiple irradiation points.

[0032] At least one attribute of the illumination point and / or illumination pattern may include attributes in the processing plane. For example, at least one attribute includes geometric features or properties such as shape (e.g., profile) and / or location (e.g., located in the processing plane and / or in the field of view of the optical sensor) and / or intensity distribution and / or spectrum. The location may be defined relative to another illumination point and / or another illumination pattern and / or a reference element.

[0033] The method further includes calibrating the manufacturing equipment based on at least one estimated attribute. In calibration, the manufacturing equipment may be calibrated or adjusted absolutely (e.g., calibrated or adjusted based on a gold standard). Alternatively, the manufacturing equipment may be calibrated by relative calibration of multiple existing components of the manufacturing equipment (e.g., by coordinating multiple deflection units and / or radiation sources). Here, the manufacturing equipment may be adjusted based on at least one estimated attribute such that the irradiation point and / or irradiation pattern to be provided by the irradiation system has a predetermined or desired attribute. For example, when at least one estimated attribute of the irradiation point and / or irradiation pattern to be provided by the irradiation system deviates from one or more desired attributes (e.g., predefined attributes), the manufacturing equipment may be calibrated to minimize or completely prevent this deviation. Calibration may include determining and / or storing one or more calibration parameters that are used during subsequent provision of the irradiation point and / or irradiation pattern to ensure the desired attributes of the irradiation point and / or irradiation pattern.

[0034] Calibration parameters can affect the control of deflection units. For example, calibration parameters are determined and / or stored, and can be used to subsequently control the deflection units. Calibration parameters can minimize the deviation of the position of the irradiation point and / or irradiation pattern provided by the corresponding controlled deflection unit from the desired position. Calibration parameters can indicate correction values ​​or / and deviation values ​​for one or more deflection units in the deflection unit to compensate for these deviation values, wherein the deflection value indicates the deviation between the planned irradiation position and the actual irradiation position irradiated by the corresponding deflection unit. Deviation values ​​or / and correction values ​​can indicate distortion of the scan field of the corresponding deflection unit. Alternatively or additionally, deviation values ​​or / and correction values ​​can indicate translation or / and rotation of the scan field of the corresponding deflection unit. Translation or / and rotation can be defined relative to an absolute reference, for example, based on predefined points in the manufacturing equipment (e.g., positions defined relative to calibration elements or positions defined relative to the build platform). It is also conceivable to define translation and / or rotation relative to another deflection unit, for example, to define translation and / or rotation relative to the coordinate system or scan field of another deflection unit.

[0035] Other properties of the irradiation point and / or irradiation pattern, such as shape, spectrum, or intensity, can also be adjusted by calibration parameters. Calibration and / or recalibration of the manufacturing equipment may include at least adjusting the irradiation power, at least adjusting the beam shape (e.g., beam cross-section) of the energy or laser beam, and / or adjusting the intensity distribution in at least one energy or laser beam.

[0036] The method may include: selecting measurements from a plurality of measurements and / or weighting the measurements from the plurality of measurements. For example, estimating at least one attribute based on the selected and / or weighted measurements. Thus, for the estimation of at least one attribute, individual measurements may be ignored and / or the measurements may be given different priorities. Selection may include filtering the measurements. Here, outliers (e.g., statistical outliers) may be filtered out and still ignored in subsequent estimations. It is also conceivable to consider such outliers for estimation, but to weight them to a lesser extent compared to other measurements. Selection and / or weighting (e.g., filtering) may be based on a recursive least squares (RLS) algorithm, a Wiener filter, or / and a Kalman filter.

[0037] Selection and / or weighting can be performed by a computational neural network (CNN). Selection and / or weighting can be based on an algorithm trained by machine learning.

[0038] Measurement results can be selected (e.g., filtered) or / and weighted based on at least partially predetermined information. Alternatively or additionally, this information can be obtained at least partially from the manufacturing process currently being performed by the manufacturing equipment. This information may include conditional data. This information may be associated with selection criteria, weighting rules, weighting factors, and / or filtering criteria used for selection and / or weighting. The selection criteria, weighting rules, weighting factors, and / or filtering criteria can be defined or determined using a recursive least squares (RLS) algorithm, a Wiener filter, and / or a Kalman filter.

[0039] This information can be associated with a workpiece to be manufactured by the manufacturing equipment. This information may include at least one attribute of the workpiece to be manufactured. The at least one attribute may include (e.g., minimum, maximum, or average) layer thickness and / or material and / or shape and / or volume of at least a portion of the workpiece (e.g., layers).

[0040] Layer thickness can be a determined or actual layer thickness of a powder layer or a portion of a powder layer in a currently manufactured workpiece. To determine the actual powder layer thickness, a light projection system (e.g., a structured light projection system, as part of a manufacturing apparatus) can be provided, configured to project light onto the surface of the powder layer, such that, based on one or more images of the powder layer thus illuminated, surface information (e.g., surface topography) of the raw material layer or a portion thereof can be acquired (e.g., via the projection system and / or control unit described herein). This surface information can be recorded, for example, after powder has been applied and / or after the powder layer or raw material layer has been illuminated. For example, surface information of a first powder layer and / or a second powder layer, which will be applied over the first powder layer, can be acquired. The difference between the surface levels of the first and second powder layers, as indicated by this surface information, can then be used as the layer thickness of the second powder layer. Of course, the same method is possible for two layer portions, one on top of the other. Typically, the build platform of the manufacturing apparatus is lowered before the second powder layer is applied. This height displacement of the surface of the first powder layer can be considered when determining the layer thickness of the second powder layer, for example, when acquiring surface information of the first powder layer before lowering it. More generally, surface information acquired using a structured light projection system allows for the determination of the actual powder layer thickness (e.g., the second powder layer). This determined powder layer thickness can then be used to select appropriate measurements from earlier measurements or to weight appropriate measurements from earlier measurements to a relatively higher degree.

[0041] This information and / or at least one attribute may include the layer thickness of the un-irradiated powder layer portion, the layer thickness of the irradiated powder layer portion, and / or the difference between these two layer thicknesses. In this case, this information may be obtained based on surface information of the (un)irradiated powder layer, for example, surface information obtained using a structured light projection system. In other words, the difference may indicate the height offset between the raw material powder layer (e.g., a portion of the raw material powder layer) and the curing plane of the irradiated raw material powder (e.g., directly below this portion).

[0042] This information can indicate the number of layers currently to be irradiated, the total number of layers (e.g., of the workpiece to be manufactured), or / or the ratio of these two values. This information can also indicate the predicted or detected thickness of the raw material powder layer. For example, this information can indicate the current settling stage of the layer thickness.

[0043] This information can indicate the irradiated area of ​​a layer of the workpiece to be manufactured. This information can indicate the variation in this area between two or more consecutive layers of the workpiece to be manufactured, for example, if the variation exceeds a predefined limit. This information can indicate the wall thickness of the workpiece to be manufactured, such as the proportion of wall thickness below a predetermined threshold and / or the proportion of wall thickness above a predetermined threshold. The wall thickness can be indicated for the workpiece to be manufactured or for one or more layers of the workpiece to be manufactured.

[0044] Alternatively or additionally, the information may include at least one process parameter of the manufacturing equipment. This information may include (e.g., at least one) process parameters of the additive manufacturing process for the workpiece to be manufactured, such as (e.g., at least one) process parameters of the currently executed manufacturing process. (e.g., at least one) process parameter may include irradiation intensity, laser power, process gas temperature, powder temperature, irradiation time, and / or scanning speed. This information may include other process parameters of the irradiation system and / or manufacturing equipment that can be adjusted during workpiece manufacturing.

[0045] Alternatively or additionally, this information may indicate the scanning angle, laser incident angle, lateral offset of the laser position between the surface plane of the unirradiated powder material and the surface of the irradiated solidified powder material, molten hole shape and / or molten pool shape.

[0046] For example, at least one attribute is estimated based on a time profile of at least one attribute (e.g., location) indicated by measurements used for estimation. At least one attribute may be estimated based on a time profile of the same attribute (e.g., location) or attributes of the same type. Alternatively or additionally, measurements may be selected and / or weighted based on a time profile of at least one attribute indicated by measurements used for estimation. At least one attribute may be selected and / or weighted based on attributes of the same type or the same type. At least one attribute indicated by a corresponding measurement is associated with a corresponding measurement time. A time series of at least one attribute may be prepared based on multiple measurements. For example, a function may be determined based on time or based on one or more function parameters (e.g., the information mentioned above), which approximates at least one attribute indicated by the measurements. At least one attribute of the irradiation point and / or irradiation pattern to be provided may then be estimated based on the time series and / or the function.

[0047] In one example, estimating at least one attribute corresponds to prediction. Estimation may include averaging, interpolating, and / or extrapolating the attribute indicated by the measurements used for the estimation. In the case of a time series, for example, extrapolation may be used to estimate at least one attribute at a future time point. In the case of a function, for values ​​of function parameters provided in the future (e.g., laser power provided in the fabrication of the next layer used to provide the irradiation point), the value of the function (e.g., the location of the irradiation point to be provided, indicated by the function) may be estimated by averaging or interpolating other function values. Similarly, other methods are possible for estimating at least one attribute by averaging, interpolating, and / or extrapolating the attribute indicated by the measurements used for the estimation.

[0048] For example, there may be a change in the conditions of the manufacturing equipment between two or more optical measurements performed in a time-shifted manner. In one example, the change in the conditions of the manufacturing equipment is due to the end or start of a manufacturing step performed by the manufacturing equipment for manufacturing a workpiece (e.g., a workpiece to be manufactured in the currently performed manufacturing process). The change in conditions may be accompanied by a change in one or more process parameters. The change in conditions may be a change in irradiation operation, a change in process gas atmosphere, a coating operation using raw materials, and / or a change in the position of the build platform of the manufacturing equipment. The change in conditions may be indicated by condition data.

[0049] The method may further include providing irradiation points and / or irradiation patterns to be provided by calibrated manufacturing equipment. For example, this includes irradiating the surface of the powder layer at the irradiation points and / or irradiation patterns. In this setup, for example, the irradiation points and / or irradiation patterns are configured with desired properties. Alternatively, in the absence of prior calibration, the irradiation points and / or irradiation patterns may have estimated properties. The irradiation points and / or corresponding irradiation patterns provided by the calibrated manufacturing equipment can be used for the manufacture of workpieces, for example, for the site-selective curing of the raw material for the powder layer.

[0050] The method may include performing optical measurements to obtain measurement results indicating at least one property of the provided irradiation point and / or irradiation pattern (e.g., by calibrated manufacturing equipment). Here, an optical sensor may record an image depicting the provided irradiation point and / or irradiation pattern. As mentioned above, the image may be recorded by a first deflection unit, but the irradiation point and / or irradiation pattern may be guided by a different deflection unit (e.g., a second or third deflection unit), for example, the irradiation point and / or irradiation pattern being projected into a processing area.

[0051] Based on the optical measurement performed after calibration, the manufacturing equipment can be recalibrated. Therefore, the method may include recalibrating the manufacturing equipment based on at least one property of the provided illumination point and / or illumination pattern. The measurement can be performed during the manufacturing process for manufacturing the workpiece. It is conceivable that, for example, when no other measurement results are available for estimating at least one property, the manufacturing equipment can be calibrated based solely on previously known measurement results (e.g., from a reference build process). However, calibration can also be performed based on the measurement results of optical measurements performed during the manufacturing process for manufacturing the workpiece. Recalibration can be performed during the manufacturing process for manufacturing the workpiece. In recalibration, only the last performed optical measurement from the previous optical measurements (e.g., including previously known measurement results from a reference build process) can be considered.

[0052] The acquired measurement results can be stored (e.g., after calibration) as part of a plurality of measurement results. This allows the measurement results to be considered for future estimation of at least one attribute. In other words, the number of measurement results used for estimation can be gradually increased, wherein the manufacturing equipment can be (re)calibrated between the execution of the corresponding optical measurements.

[0053] Based on at least one estimated attribute and / or based on calibration of the manufacturing equipment, at least one of the following may be defined: the expected attributes of the illumination point to be provided (e.g., provided in the future or subsequently) and / or the expected attributes of the illumination pattern to be provided (e.g., provided in the future or subsequently); the number and / or time offset of optical measurements to be performed for recalibration; and the spatial distribution of the optical measurements to be performed for recalibration. The spatial distribution may include one or more fields of view of the optical sensor and / or one or more locations of the illumination point to be provided and / or the illumination pattern. The spatial distribution may be defined by the deflection of a first deflection unit, a second deflection unit, or / and a third deflection unit, which are provided for the optical measurements to be performed for recalibration.

[0054] As mentioned in the first aspect, the manufacturing apparatus may include an optical sensor, a first deflection unit, a second deflection unit, and / or a third deflection unit. Here, the optical sensor can acquire at least one attribute of the irradiation point and / or irradiation pattern via the first deflection unit, and the corresponding irradiation point and / or irradiation pattern can be located via the second deflection unit, for example, at a position on the powder surface and / or in the processing area. Alternatively or additionally, the corresponding irradiation point and / or irradiation pattern can be located via the second deflection unit or the third deflection unit.

[0055] Calibrate or / and recalibrate the manufacturing equipment. This may include coordinating a first deflection unit with a second deflection unit, or / and coordinating a second deflection unit with a third deflection unit, or / and coordinating a first deflection unit with a third deflection unit. Here, the coordinate transformation between the projection coordinate systems of the coordinated deflection units can be determined. Coordination can minimize or completely avoid undesirable offsets between the positions of the irradiation points and / or irradiation patterns provided by the two deflection units. Coordination of the two deflection units can be performed such that the coordinated deflection units are calibrated relative to each other. However, coordination can also be performed such that the two deflection units are calibrated absolutely, for example, based on at least one point in the processing area, based on at least one reference element, or / and based on at least one point on the powder layer to be cured. Attached Figure Description

[0056] These and other aspects of the invention will be described in more detail below with reference to the accompanying drawings, in which: Figure 1 A schematic representation of a manufacturing apparatus according to this disclosure is shown; Figure 2 A flowchart of the method according to this disclosure is shown; Figure 3 A schematic representation is shown to illustrate the height offset; Figure 4 A schematic representation is shown to illustrate the transient behavior of layer thickness; Figure 5 A schematic representation is shown to illustrate the lateral offset that depends on the laser incident angle; Figure 6 Schematic representations illustrating different molten hole and molten pool shapes are shown; and Figure 7 A timeline is shown using an example measurement of time. Detailed Implementation

[0057] Figure 1System 2 includes an additive manufacturing apparatus 3 and an irradiation system 4. The additive manufacturing apparatus 3 is adapted for powder bed curing, and the irradiation system 4 is used to provide irradiation points and / or irradiation patterns in the processing area 6. When the raw material powder layer 8 is located on the carrier 10 of the manufacturing apparatus, irradiation points and / or irradiation patterns can be provided on the surface 12 of the powder layer 8, in which case the surface 12 of the powder layer 8 is located in the processing plane 13 of the manufacturing apparatus 2. To provide irradiation points and / or irradiation patterns, the irradiation system 4 includes a plurality of irradiation sources 14, 16, 18, which can be guided as directional beams 21, 23, 25 into the processing area 6 by corresponding deflection units 20, 22, 24. For example, the deflection units 20, 22, 24 are used to position the laser beam on the surface 12 of the powder layer 8 for position-selective melting or sintering of the powder material, and each of the deflection units 20, 22, 24 may include a 2-axis scanning system having one or more mirrors that can be moved in a controllable manner. Manufacturing apparatus 3 also includes optical sensors 26 and 28, each of which is capable of detecting at least a portion of the processing area via dynamic liquid lenses 30 and 32 with adjustable focal points. The field of view of optical sensors 26 and 28 can be shifted via associated deflection units 20 and 24. Figure 1 The central line of sight 34 of the optical sensor 26 is shown by way of example. Depending on the arrangement of the optical sensor and the configuration of the deflection unit 20, the central line of sight 34 may deviate from or coincide with the path of the directional beam 21. A reference element 36 is mounted at a previously known location near the carrier 10. The system 2 also includes a device 38 for calibrating the manufacturing equipment 3. The device 38 includes a control unit 40 for controlling the irradiation system 4.

[0058] Figure 2 A flowchart of a method according to this disclosure is shown. This method can be performed on system 2, for example by control unit 40 of device 38.

[0059] This method is based on multiple measurements using optical measurements performed in a time-shifted manner. For example, these measurements include images of the processing area recorded by optical sensors 30, 32 through dynamic lenses 30, 32. Each of these images includes a depiction or reproduction of an illumination point and / or illumination pattern provided by illumination system 4 at the time of image recording, and may also include a depiction of reference element 36. Thus, the images indicate at least one attribute of the provided illumination point and / or illumination pattern. The at least one attribute may be defined by illumination system 4, for example, by means of illumination system 4. Examples of the at least one attribute include location, shape, intensity (distribution), and spectrum, where location is considered advantageous as an attribute, for example. Therefore, while this disclosure is not limited thereto, focus will be placed on location as the at least one attribute hereinafter.

[0060] In optional step 202, a measurement result from a plurality of measurement results is selected and / or a weighting is applied to the measurement results from a plurality of measurement results. The selection may include filtering the plurality of measurement results. Here, a measurement result that is particularly meaningful for subsequently estimating at least one attribute of the irradiation point and / or irradiation pattern to be provided is selected, or the aforementioned particularly meaningful measurement results are weighted to a higher degree.

[0061] Measurement results and / or weighting of measurement results can be based on at least partially predetermined information. Alternatively or additionally, this information can be obtained at least partially from the manufacturing process currently being performed by manufacturing equipment 3. For example, if an individual measurement result (e.g., from a previous reference manufacturing process or from the currently performed manufacturing process) is associated with a laser power of 1000W, and other measurement results are associated with a laser power of 500W, then in the case of an irradiation point subsequently provided with a laser power of 500W (e.g., provided in the currently performed manufacturing process), the measurement result associated with the 500W laser power can be selected or / or the measurement result associated with the 500W laser power can be weighted to a greater extent. Alternative laser power or other (process) parameters associated with the measurement results can be considered besides laser power. It is also conceivable to use statistical criteria to select or weight measurement results. Thus, for example, statistical outliers can be filtered out from the measurement results.

[0062] The information used for selection and / or weighting can be associated with the workpiece to be manufactured by the manufacturing equipment, such as the workpiece's shape, material, volume, and / or layer thickness. For example, the workpiece to be manufactured may have a layer thickness of 200 μm. In this case, measurements obtained based on a powder layer with a thickness of 50 μm can be weighted less, or the aforementioned measurements can be omitted from subsequent estimation. On the other hand, measurements associated with a layer thickness of 150 μm can be selected, and / or the aforementioned measurements can be weighted more.

[0063] This information indicates the height offset between the raw material powder layer and the solidified plane of the irradiated raw material powder. For example, this height offset occurs when the powder layer is remelted to form a denser layer, due to the compaction of the powder layer during irradiation.

[0064] This effect is Figure 3 As shown in the image. Figure 3 As shown, the unirradiated raw material powder layer 326 (e.g., corresponding to layer 8) comprises powder particles 302 of varying sizes. The powder layer 326 is applied onto the cured underlayer 324. The powder particles 302 form a powder layer surface 304, the surface roughness of which is determined by the particle size and particle size distribution of the raw material powder. Figure 3 In this context, the surface roughness is indicated by the applied profile 306. The laser beam 21 has a focal plane 308, which lies within the plane of the surface 304. However, the volume of the powder layer decreases due to the melting of the powder layer. Therefore, the surface 310 of the irradiated and thus melted or solidified powder layer 311 lies below or deeper than the surface 304 in the height / z direction. This height offset is indicated by reference numeral 312. The height difference or height offset depends on the properties of the raw material powder (e.g., material type, particle size distribution, bulk density, etc.) and on the properties of the powder particles (e.g., the shape of the particles or powder particles 302, etc.). Compared to the case of powders with higher bulk density, in the case of powders with lower bulk density, the solidified plane 310 will be further away from the unirradiated powder bed plane 304.

[0065] Height deviation can also be affected by material loss because the cured layer is not formed monolithically from the irradiated original powder material. Therefore, splattered molten powder material is typically formed during irradiation, which subsequently does not form part of the cured layer 311, and a portion of the irradiated powder material transforms into the gas phase. This material loss inevitably leads to a further reduction in layer height compared to the unirradiated powder layer 304, i.e., an increase in height deviation 312. This material loss depends in particular on the laser power, laser spot size, laser scanning speed, and the process gas flow in the region of the irradiated powder surface, and optionally on other parameters.

[0066] It is conceivable to select measurements associated with the height difference 312 and / or the parameter values ​​that affect the height difference 312 (e.g., material type, bulk density, laser spot size, etc.) for estimation, or / and to a greater extent weight the aforementioned measurements, so as to match or adapt the predicted height difference or the parameter values ​​of the impending illumination particularly well.

[0067] It has been found that the thickness of the applied powder layer, which depends on the specific material, is established only after multiple powder layers have been applied. This behavior is as follows: Figure 4 As shown. When the first powder layer is applied to a substrate (e.g., a previously cured layer 324 or the build platform of an additive manufacturing apparatus), the powder layer 326 has a height hl. This height hl corresponds to the height displacement caused by the reduction of the build platform before the powder layer 326 is applied. Upon irradiation, the volume of the powder layer 326 decreases, resulting in the height offset 312 or Δh mentioned above. If a second layer is applied to the so-called cured first layer 311 after the build platform has been reduced again by the same height displacement hl, the second powder layer typically has a layer thickness hl + Δh1. Therefore, the applied second raw material powder layer is Δh1 thicker than the applied first raw material powder layer 326. Compared to the first powder layer, the second powder layer shrinks by a greater amount upon irradiation because the second powder layer is relatively thick. Similarly, the corresponding application applies to the third, fourth, and so on. Only after multiple (e.g., 5, 6, 7, 8, 9, 10, 15, or more) layers have been applied does the height offset 312 between the surface of the newly applied powder layer and its irradiated surface become substantially constant.

[0068] To account for this settling behavior, measurements can be selected or weighted based on information indicating the number of layers currently being irradiated, the total number of layers, or / and the ratio of these two values. This information can indicate the predicted or detected thickness of the raw material powder layer. For example, measurements matching the current settling stage of the layer thickness can be selected, or / or weighted to a higher degree.

[0069] Significant or abrupt changes in the irradiation area from the first layer to subsequent layers can have a major impact on the location of the irradiation point. Therefore, it is possible to configure information for one or more powder layers to indicate the shape or area of ​​a portion of the corresponding powder layer to be cured for manufacturing the workpiece, for example, to indicate abrupt changes in the irradiation area.

[0070] Typically, the powder layer to be cured by a light beam is distributed across a scanning field area. Large areas of the powder layer to be illuminated in the first scanning field area (e.g., located at the edge of the scanning field, i.e., at the point of maximum deflection of the beam provided by the corresponding deflection unit) can cause the laser beam to remain in that first scanning field area for a longer time, while smaller areas of the powder layer in different second scanning field areas (e.g., located in the middle of the scanning field, i.e., at the point of minimum deflection of the same beam) require a shorter laser beam dwell time. These different dwell times can result in different thermal loads on the corresponding deflection units, which can affect the irradiation point and / or the irradiation pattern. To account for this, the information used may also indicate the scanning time, scanning speed, scanning pattern, or irradiation vector. For example, this information may indicate the orientation and / or direction of travel of the irradiation vector, wherein the irradiation vector is arranged and illuminates the powder layer.

[0071] The aforementioned height difference 312 between the unirradiated powder layer surface 304 and the irradiated powder layer surface 310 can also cause a lateral deflection of the incident laser beam 21, for example, when the beam strikes the surface to be irradiated at an acute angle of <90° (i.e., flatly). For example, this deflection can result in the laser beam 21 striking the powder material (irradiated or unirradiated) at an undesired location. The greater the lateral deflection, the larger the deflection angle of the laser beam 21, or the flatter the impact of the laser beam 21 on the surface. In the case of a large deflection angle of the laser beam 21, for example, in the case of a large powder layer thickness (e.g., 300 μm), the expected offset (e.g., in the XY direction) between the impact position on the upper side 304 of the uncured powder layer 326 and the upper side 310 of the molten and thus compacted layer 311 of the component is larger. This relationship is as follows: Figure 5 As shown. Figure 5 As indicated, the deflection unit 20 or the laser scanner can be activated, causing the laser beam 21 to be at point P at an angle 314. L The impact occurs at point P on the powder surface 304. However, this surface 304 is offset by a height of 312 compared to the surface 310 of the cured powder layer. Therefore, point P... L Unlike the laser beam, which may strike position 316 on the already solidified powder layer, point P can be calculated based on the height offset and laser angle 314. L The offset between 316 and 312. In calibration, this offset can be considered as a correction value, for example, where (e.g., in workpiece manufacturing) the laser beam position is controlled based on the surface 310 of a cured powder layer (e.g., 311). The following applies: tan(laser angle) = h / d = (height offset 312) / (offset Δd in the XY direction). Figure 3 The text also shows the lateral offset (“X / Y offset”).

[0072] When a laser beam strikes a powder surface, a so-called "keyhole" or molten pool is typically formed in the area of ​​direct impact. This area is largely devoid of powder material, as it evaporates at this point. The shape of the molten pool within the powder layer varies depending on the impact angle of the laser beam. This, in turn, affects the shape of the molten pool, and ultimately, the profile of the irradiated surface or the properties of the finished workpiece. This effect is present in… Figure 6 The instructions are in accordance with the central government.

[0073] Figure 6 Three side views of the molten hole 318 and associated molten pool 320, depending on the laser impact angle of the laser beam 21 on the powder layer surface 304, are shown at the top. The bottom image shows the corresponding top view. As can be seen, in the side and top views, the outer contour of the molten pool 320 varies according to the laser impact angle. For example, the deviation of the molten hole 318 can be defined by the molten hole depth, the deflection angle (e.g., its tangent), and material factors. In the case of multiple deflection units 20, 22, 24, it is possible that closely adjacent regions of the powder layer 326 irradiated by different deflection units 20, 22, 24 have different molten hole and / or molten pool shapes upon irradiation. This can result in a identifiable transition and / or the formation of mechanically unstable boundary regions between adjacent regions after the workpiece is manufactured. To avoid this effect, only measurements associated with the relevant laser scanning angle, laser impact angle, molten hole, and / or molten pool shape can be considered.

[0074] Therefore, in order to take into account the effects mentioned above, in addition to including height offset or as a substitute for height offset, the information used may also include, for example, scanning angle, laser impact angle, lateral offset, molten hole shape and / or molten pool shape.

[0075] The rules used for selection and / or weighting (e.g., selection criteria, filtering parameters, weighting rules, and / or weighting factors) can be configured to be variable, i.e., they can change over time, for example, based on multiple measurements. For example, the rules can be adjusted if additional measurements are provided. The rules can be provided and / or adjusted from time to time using a trained machine learning system. Measurements from one or more reference manufacturing processes can be used as training data for the machine learning system, with the selection and / or weighting of the measurements defined by the user. The machine learning system can then consider additional measurements acquired during the currently executed manufacturing process to adjust the rules. It is also conceivable that the machine learning system not only manages the rules but also executes step 202. Here, the machine learning system can be configured as part of control unit 40.

[0076] In step 204, at least one attribute of the irradiation point and / or irradiation pattern to be provided is estimated based on multiple measurements. If step 202 has been performed prior, step 204 utilizes (e.g., only) the selected and / or weighted measurements to estimate at least one attribute.

[0077] For example, estimating at least one attribute includes averaging, interpolating, and / or extrapolating the attribute indicated by measurements used (e.g., selected and / or weighted) for the estimation. For instance, if the selected images indicate the corresponding depicted location of the irradiation point as at least one attribute, wherein each image is associated with a planned location of the irradiation point, then the predicted location provided by the corresponding deflection unit can be associated with the irradiation point to be provided at the planned location in the future. Therefore, the expected location can be estimated, for example, by averaging, interpolating, and / or extrapolating the location indicated by the measurements used for the estimation. Other attributes, such as the intensity of the irradiation pattern, can also be estimated in this manner.

[0078] Steps 202 and / or 204 can be performed based on time profiles of the same attributes. In other words, not only the measurement results themselves can be considered, but also the time profiles of one or more attributes indicated by the measurement results, to select measurement results and / or weight and / or estimate at least one attribute. For example, a time profile can indicate the change in distance over time between the measured location of the irradiation point and the planned location. In this way, the future location of the irradiation point can be estimated. As another example, the decrease in intensity of the irradiation pattern over time can be analyzed to estimate the future intensity of the irradiation pattern to be provided. Therefore, not only multiple measurement results are analyzed, but also the temporal relationships between the multiple measurement results.

[0079] Because the measurements are based on optical measurements performed in a time-shifted manner, different events may exist between individual measurements. For example, between two or more optical measurements performed in a time-shifted manner, there may be changes in the conditions of the manufacturing equipment 3. Examples that may be mentioned include changes in irradiation operations, changes in process gas atmospheres, operations involving coating with raw materials to form powder layer 8, and / or changes in the position of carrier 10. Estimates can then be performed, for example, using measurements associated with the same conditions of the manufacturing equipment (e.g., measurements obtained only at the same powder temperature and / or gas temperature).

[0080] In step 206, the manufacturing equipment 3 is calibrated based on at least one estimated attribute. Calibration ensures that at least one attribute (e.g., position) of the irradiation point and / or irradiation pattern provided after calibration corresponds to the desired attribute. Calibration may include calibrating the irradiation system 3, such as calibrating lasers 14, 16, 18 and / or deflection units 20, 22, 24. For this purpose, calibration parameters may be determined, which are then used to control the irradiation system 4. Calibration parameters may indicate offset or position correction functions and are used to ensure that the irradiation point is provided at the planned position after calibration. Calibration may include coordinating multiple deflection units 20, 22, 24 with each other. Deflection units 22, 24 may be coordinated relative to each other when measurements indicate, for example, the position of an irradiation point located on one hand by deflection unit 22 and the position of an irradiation point located on the other hand by deflection unit 24. If the measurement result is based on an image recorded by sensor 30 through deflection unit 20, the deflection unit can be coordinated relative to one or both of the deflection units 22, 24 used for illumination during image recording. For example, instead of relative calibration of deflection units 20, 22, 24, one or more deflection units can be calibrated absolutely based on the position of reference element 36 in the image recorded by sensor 30 and / or 32. As mentioned above, calibration, in addition to position correction, can also ensure other properties of the illumination point to be provided, such as the intensity or profile of the illumination point. Such properties can also be adjusted by calibration relative to the properties of the illumination point provided through different deflection units or based on an absolute reference.

[0081] After calibration, optional step 208 can be performed, for example, during the manufacturing process for producing the workpiece, such as during, before, or after curing of the area of ​​powder layer 8 to produce the workpiece. In step 208, irradiation points and / or irradiation patterns are provided by manufacturing equipment 3, for example, by a calibrated irradiation system 4. For example, if deflection unit 22 has been calibrated, the irradiation point or irradiation pattern will be guided onto powder layer 8 by deflection unit 22. Alternatively, if additional deflection units 20, 24 are calibrated relative to deflection unit 22 or absolutely calibrated in the same manner as deflection unit 22, irradiation can be achieved by one of those deflection units 20, 24.

[0082] In a subsequent optional step 210, an optical measurement is performed to obtain a measurement result. For example, an image may be recorded depicting the illumination point or illumination pattern provided in step 208. The measurement result also indicates properties of the provided illumination point and / or illumination pattern, such as intensity, location, or spectrum.

[0083] In an optional subsequent step 212, the manufacturing equipment is recalibrated based on the measurement results obtained from step 210. It is conceivable that, among the available measurement results, only those obtained in step 210 can be used for recalibration. Alternatively or additionally, the measurement results obtained in step 210 can be stored, for example, as part of a plurality of measurement results. Then, one or more steps 202-206 can be performed again, where the plurality of measurement results also includes those from step 210.

[0084] It is conceivable that at least one estimated attribute (e.g., the estimated position or the estimated positional deviation relative to a reference position) can influence steps 208 and / or 210. For example, the estimated attribute can be used to define or determine the number and / or time offset of optical measurements to be performed for recalibration. For example, if the estimated positional deviation is greater than a determined threshold, multiple iterations of steps 208, 210 can be provided to subsequently recalibrate the manufacturing equipment 3 in step 212. Alternatively or additionally, the spatial distribution of the optical measurements to be performed for recalibration can be defined by at least one estimated attribute. For example, the spatial distribution can define the planned location of the illumination point to be provided in the measurement and / or the field of view to be used for image recording. For example, the spatial distribution can be selected such that the predicted positional deviation from the planned location exceeds a predetermined threshold.

[0085] Figure 7 A timeline over time t is shown using an exemplary measurement time. The measurement results of the optical measurements selected for estimation are indicated by exemplary measurement groups C1 and C2. In the example shown, the measurement results are associated with different workpiece information S1, S2 (e.g., different layers of the component), which is used to select the measurement results used for estimation. It can be seen that not all measurement results based on optical measurements I... n All are used for estimation, but in each case, target sub-selection I1-I3 or I3-I5 is used. These measurements are based on optical measurements performed at different measurement times. Other measurement data at different time points (e.g., conditional data or data from other sensors) are denoted as M1-M3. Measurement data from temperature sensors (e.g., powder temperature, process gas temperature) are denoted as T1, T2. This disclosure is not limited to... Figure 7 Examples include, for instance, alternative workpiece information that can be based on other information, such as measurement results T. n or / and M n To select the measurement result I to use for estimation n or / and the measurement results I to be used for estimation n Weighting is applied.

[0086] The techniques described above and further details will be explained in other words below.

[0087] If deflection units 20-24 are activated and remain unchanged, the position irradiated by deflection units 20-24 can change over time. Calibration of the manufacturing apparatus 3 allows adjustment of the scanning angle of the scanning system of the deflection units 20-24, ensuring that the planned irradiation position in the processing plane 13 is actually irradiated. Because the manufacturing apparatus 3 includes multiple deflection units 20-24, calibration is used to ensure, for example, that the deflection units 20-24 are calibrated relative to each other or / and absolutely calibrated. Therefore, after calibration, the position and / or focus of the irradiation point and / or irradiation pattern located by the deflection units 20-24 can coincide at any desired location in the processing area 6 shared by the deflection units 20-24, even if each deflection unit is activated based on an absolute machine coordinate system (MKS).

[0088] During the manufacturing process, thermal and other physical effects on the irradiation system 4 can cause the positions and / or focal points of the irradiation points and / or irradiation patterns to no longer coincide. This can result in the inability to produce seamless parts. While such orientation errors can be compensated for during manufacturing through calibration based on individual measurements, this method, relying solely on individual measurements, is susceptible to interferences such as the effects of imaging methods, materials, or beam parameters at the corresponding image recording times. Furthermore, recording a large number of individual measurements may require undesirable interruptions to the manufacturing process.

[0089] For example, to reduce the impact of noise and increase the accuracy of calibration (e.g., to correct the image for the scanning angle at a position in the machine coordinate system), the attributes of the illumination points and / or illumination patterns determined from the recorded images (e.g., the position of the illumination points, the distance between the illumination points, or the distance from an external reference point (e.g., reference element 36)) are not interpreted individually, but in combination, preferably in a time-series manner. The impact of noise can be reduced by averaging and filtering. Between image recordings, changes in machine conditions may occur, but not necessarily, such as illumination, coating, and adjustment operations of the carrier 10 (also referred to as the component carrier structure, substrate, or build platform). The filtered measurement results can be located in the original image or in the reverse projection scanner or machine coordinate system. Therefore, calibration is performed not only using the single measured actual position, but also using an estimate based on multiple measurements of at least one attribute (e.g., position).

[0090] In temporal and / or spatial coordinates, filtering can be adaptive. In the case of adaptive filtering, filter parameters can be adjusted based on machine learning concepts. Thus, for example, filter parameters can be adjusted based on changes in the illuminated area or on the number of deflection units used. Therefore, changes in the measurement can be adaptively adjusted, making this what can be called self-adaptive.

[0091] To obtain measurement results based on optical measurements (e.g., images), a brightness-based adaptive method can be used, which does not employ a fixed threshold. This brightness-based adaptive method differs from thresholding methods using a fixed threshold or methods using multiple thresholds. The intensity of the illuminated point can vary significantly, resulting in a large range of brightness values ​​for the depicted point. Compared to this adaptive method, fixed thresholding methods or methods using multiple fixed thresholds for detecting the depicted point are less advantageous.

[0092] For both lasers and powder materials, parameters used for laser control (such as power, interaction time, etc.) can be adjusted independently.

[0093] Information about the component to be produced that is known before the production process begins (such as energy, power, area, geometry, and volume for each layer) can be included to adjust filter parameters. This information can also be used to adjust the frequency of measurements or the number and spatial distribution of measurements.

[0094] In another example, measurement data M from the manufacturing process may be included. n (For example, laser power, illumination time, and distance) to adjust filter parameters. This information can also be used to adjust the frequency, number, and / or spatial distribution of measurements, and / or the adjustment rate of the filtering method used.

[0095] In processing region 6, which is the common overlapping area of ​​deflection units 20-24, illumination points and / or illumination patterns are generated by a sub-number of deflection units in deflection units 20-24 and energy beams 21-25 deflected by the deflection units from energy sources 14-18. These points or patterns are depicted by optical sensor 26 (e.g., a camera) through deflection unit 20, without involving deflection unit 20 when providing the points or patterns. In order to compare the focal position of deflection unit 20, which previously defines the field of view of optical sensor 26, with the focal positions of other deflection units 22, 24, the image recording sequence can be repeated, wherein different optical sensors 28 and associated deflection units 24 are used.

[0096] Images recorded by the respective optical sensors 26, 28 are focused onto the processing plane 13, which can be achieved by means of dynamic lenses 30, 32 associated with the respective sensors, preferably liquid lenses (e.g., focus-adjustable liquid lenses).

[0097] In order to calibrate the deflection units 20-24 relative to an external absolute reference (by comparing the deflection units 20-24 relative to each other using the method described above), the calibration element 36 may be disposed in or near the processing area. This calibration element 36 may be physically marked at a predetermined absolute position or projected by a light pattern.

[0098] It should be understood that System 2 and the reference described herein can be modified. Figure 2 The method described herein. Therefore, for example, additional deflection units and corresponding radiation sources may be provided, or only two deflection systems in total may be provided. Further modifications to the system and method, as well as further technical advantages of the techniques described herein, will become apparent to those skilled in the art based on this disclosure.

Claims

1. A method for calibrating manufacturing equipment (3), said manufacturing equipment being adapted to perform additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer, said method comprising: Based on multiple measurements (I1-I5) performed in a time-shifted manner, at least one attribute of the illumination point and / or illumination pattern to be provided is estimated (204), wherein each measurement indicates at least one attribute of the illumination point and / or illumination pattern at a corresponding measurement time; and The manufacturing equipment (3) is calibrated (206) based on at least one of the estimated properties.

2. The method according to claim 1, further comprising: Select the measurement result (I1-I3; I3-I5) from the plurality of measurement results (I1-I5) and / or weight the measurement results (I1-I3; I3-I5) from the plurality of measurement results (I1-I5) (202). The at least one attribute is estimated based on the selected and / or weighted measurement results.

3. The method according to claim 2, wherein, The measurement results (I1-I3; I3-I5) and / or the weighting of the measurement results (I1-I3; I3-I5) are selected based on information that is at least partially predetermined and / or at least partially obtained from the manufacturing process currently performed by the manufacturing equipment (3).

4. The method according to claim 3, wherein, The information is associated with a workpiece to be manufactured by the manufacturing equipment (3), and / or the information includes at least one process parameter of the manufacturing equipment (3).

5. The method according to claim 4, wherein, The information includes at least one attribute of the workpiece to be manufactured and / or at least one process parameter of the additive manufacturing process for the workpiece to be manufactured, such as at least one process parameter of the currently executed manufacturing process.

6. The method according to any one of claims 1 to 5, wherein, Estimate the at least one attribute based on the time profile of the same attribute, and / or select the measurement results (I1-I3; I3-I5) based on the time profile of the same attribute, or / and weight the measurement results (I1-I3; I3-I5).

7. The method according to any one of claims 1 to 6, wherein, Estimating the at least one attribute includes averaging, interpolating, and / or extrapolating the attribute indicated by the measurement results used to make the estimation.

8. The method according to any one of claims 1 to 7, wherein, There may be a change in the conditions of the manufacturing equipment (3) between two or more optical measurements performed in a time-off manner, such as a change in irradiation operation, a change in process gas atmosphere, a coating operation using raw materials, or / and a change in the position of the construction platform (10) of the manufacturing equipment (3).

9. The method according to any one of claims 1 to 8, further comprising: The irradiation point and / or irradiation pattern to be provided is provided by the calibrated manufacturing equipment (3) (208); Perform (210) optical measurements to obtain measurement results indicating at least one attribute of the provided irradiation point and / or irradiation pattern; as well as The manufacturing equipment (3) is recalibrated based on at least one attribute of the provided irradiation point and / or irradiation pattern, and / or the acquired measurement results are stored as part of the plurality of measurement results (I1-I5).

10. The method according to claim 9, wherein, Based on at least one estimated attribute and / or based on the calibration of the manufacturing equipment (3), at least one of the following is defined: The desired properties of the irradiation point and / or irradiation pattern to be provided; For example, the number of optical measurements and / or time offsets that need to be performed for recalibration; For example, the spatial distribution of optical measurements to be performed for recalibration.

11. The method according to any one of claims 1 to 10, wherein, The manufacturing equipment (3) includes an optical sensor (26), a first deflection unit (20), a second deflection unit (22) and / or a third deflection unit (24), wherein: (i) The optical sensor (26) can acquire at least one attribute of the illumination point and / or illumination pattern through the first deflection unit (20), and can locate the corresponding illumination point and / or illumination pattern through the second deflection unit (22). (ii) The optical sensor (26) is able to acquire at least one attribute of the irradiation point and / or irradiation pattern, and is able to locate the corresponding irradiation point and / or irradiation pattern by means of the second deflection unit (22) or the third deflection unit (24). The calibration (206) and / or recalibration (212) of the manufacturing equipment (3) includes: coordinating the first deflection unit (20) with the second deflection unit (22), or / and coordinating the second deflection unit (22) with the third deflection unit (24), or / and coordinating the first deflection unit (20) with the third deflection unit (24).

12. An apparatus (38) for calibrating a manufacturing device (3), said manufacturing device being adapted to perform additive manufacturing of three-dimensional workpieces by means of position-selective irradiation to solidify raw materials layer by layer, wherein, The manufacturing equipment includes an irradiation system (4) for providing irradiation points and / or irradiation patterns, wherein the device (38) includes a control unit (40) for controlling the irradiation system (4), the control unit being adapted to: Based on multiple measurements (I1-I5) performed in a time-shifted manner, at least one attribute of the illumination point and / or illumination pattern to be provided is estimated (204), wherein each measurement indicates at least one attribute of the illumination point and / or illumination pattern at a corresponding measurement time; and The additive manufacturing equipment (3) is calibrated (206) based on at least one of the estimated properties.

13. The apparatus (38) according to claim 12, wherein, The control unit (40) is adapted to perform the method according to any one of claims 2 to 11; or / and The manufacturing equipment (3) includes an optical sensor (26), a first deflection unit (20), a second deflection unit (22) and / or a third deflection unit (24), wherein the deflection units are configured such that: (i) The optical sensor (26) can acquire at least one attribute of the illumination point and / or illumination pattern through the first deflection unit (20), and can locate the corresponding illumination point and / or illumination pattern through the second deflection unit (22). (ii) The optical sensor (26) can acquire at least one attribute of the irradiation point and / or irradiation pattern, and can locate the corresponding irradiation point and / or irradiation pattern by means of the second deflection unit (22) or the third deflection unit (24).

14. A system (2), comprising: The apparatus (38) according to claim 12 or claim 13; and The manufacturing equipment (3).

Images