Method for monitoring a powder material layer of a manufacturing device, as well as a manufacturing device

Abstract

Method for monitoring a powder material layer of a manufacturing device (1), wherein the manufacturing device (1) is configured to produce at least one component (19) layer by layer from a plurality of powder material layers of a powder material (15) arranged successively in a layer sequence in a working area of ​​the manufacturing device (1) by locally selective solidification of the powder material (15) arranged in the working area by means of energy beams (11a, 11b, 11c), wherein the method comprises the following steps: a) applying a powder material layer in the working area by means of an application device (17), b) taking several images of the entire or a partial area of ​​the powder material layer by means of a working area detection device (12), while the powder material (15) arranged in the working area is being solidified by means of energy beams (11a, 11b, 11c).11c) is exposed or while the application device (17) is within the working area, and c) processing the captured images of the powder material layer.

Description

Technical area

[0001] The invention relates to a method for monitoring a powder material layer of a manufacturing device, wherein the manufacturing device is configured to produce at least one component layer by layer from a plurality of powder material layers of a powder material arranged in a layer sequence sequentially in a working area of ​​the manufacturing device by locally selective solidification of the powder material arranged in the working area by means of energy beams, as well as to a manufacturing device. Background of the Revelation

[0002] In additive manufacturing, e.g., selective laser sintering or selective laser melting, a powdered material, e.g., a metal or ceramic powder, is irradiated with electromagnetic radiation. Thin powder layers are successively applied in a chamber on a build platform to form three-dimensional objects by irradiating the respective powder layers with an irradiation beam, e.g., a laser beam. Corresponding devices are referred to as additive manufacturing devices, 3D printing systems, selective laser sintering machines, or selective laser melting machines, and the like. For the operation of such a device, see, for example, EP 2 732 890 A2.

[0003] In recent years, the additive manufacturing of components has also gained importance in industrial settings. Additive manufacturing in a powder bed (Powder Bed Fusion, PBF), in which thin layers of powder, e.g., made of metal, ceramic, or thermoplastic powder, are gradually applied and locally solidified with one or more beams to successively build up the component, is particularly suitable for the production of complex and delicate components. Machines suitable for performing a PBF process are referred to below as PBF machines. Lasers and electron beam systems are typically used as beam sources. When a laser source is used, the process is also referred to as Powder Bed Fusion - Laser Based (PBF-LB). The beam can sinter or melt the powder to solidify it, thereby bonding it to previously solidified component layers.Depending on the beam source, sintering is referred to as selective laser sintering or electron beam sintering, while melting is referred to as selective laser melting or electron beam melting. Powder-bed-based additive manufacturing of metal powder using a laser beam is also known as laser metal fusion.

[0004] Since the component is produced layer by layer, such an additive manufacturing process is relatively time-consuming. To reduce production time, multiple energy beams—for example, 2, 3, 4, 8, 12, or 16—are used instead of a single energy beam. A manufacturing device used in this process typically has at least one scanner device configured to shift the energy beams.

[0005] By using multiple energy beams, it is possible for a first energy beam to produce a first component in a work area of ​​the manufacturing device, while at the same time a second energy beam produces a second component in the work area.

[0006] In these known processes, the quality of the powder material layer to be machined in the powder bed, as well as the quality of the molten components, are crucial factors for producing high-quality components. The quality of the powder material layer to be machined also affects the tools used in the production equipment. Likewise, poor tool quality leads to an inadequate powder material layer.

[0007] DE 10 2018 218 991 A1 therefore proposes taking optical images of the working layer of the powder bed during the production of a component and examining these images for defects in the working layer, such as insufficient powder dosage or smoke particles. For defects that can be corrected, such as an incomplete working layer, the production system can be controlled in such a way that the working layer or powder material layer is completed before the powder is melted by the exposure source. In the case of more serious defects, the system is shut down to prevent damage to the tools, especially the powder coating tools. However, this latter measure leads to undesirable delays in the production process, particularly in the series production of components.

[0008] In conventional manufacturing systems, optical images of the working layer of the powder bed are taken during the downtime between the coating process and the exposure process. The coating tool is located outside the build platform during image acquisition, and the exposure source(s) are switched off. Existing manufacturing systems therefore require interruption of component production in order to take an optical image of the working layer of the powder bed and check its quality. Powder bed quality here refers to a uniform layer of powder material. Furthermore, the term "quality" encompasses the detection of rising components, e.g., due to local overheating in the component, and defects in the coating tool or application device.

[0009] The present invention is based on the object of avoiding such delays and interruptions in the production of components in powder bed processes due to the monitoring of a powder material layer.

[0010] In general, the present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems, and in particular to reducing or completely eliminating downtime in the process.

[0011] Thus, the present disclosure is directed, at least in part, to improving upon or entirely overcoming one or more aspects of prior systems. Summary of Revelation

[0012] The object is achieved by providing the present technical teaching, in particular the teaching of the independent claims as well as the preferred embodiments disclosed in the dependent claims and the description.

[0013] The object is achieved in particular by a method for monitoring a powder material layer or building material layer of a manufacturing device, wherein the manufacturing device is set up to produce at least one component or three-dimensional object layer by layer from a plurality of powder material layers of a powder material or building material arranged in a layer sequence chronologically successively in a working area of ​​the manufacturing device.Building material by locally selective solidification of the powder material arranged in the work area by means of energy beams, the method comprising the following steps: a) applying a layer of powder material in the work area by moving, in particular horizontally, an application device, b) taking several images of the entire area or a partial area of ​​the powder material layer by means of a work area detection device, while the powder material arranged in the work area is exposed to energy beams or the application device is located within the work area - which means in particular that the application device is currently moving over the work area and applying a layer of powder material, is carrying out an empty run, or is stationary in the work area - and c) processing the recorded images of the powder material layer.

[0014] Advantageously, this innovative process can shorten or even completely eliminate the downtime between moving the application device and exposing the powder material layer. Furthermore, by taking multiple images of the powder material layer using a workspace detection device, such as a camera, and processing the recorded images, disruptive influences on the images, such as the application device or process emissions, can be cut out or eliminated. For example, different parts of several images can be combined into one image, whereby this combined image shows neither the application device nor process emissions. However, it is also possible to differentiate between an image that contains exclusively freshly coated areas and an image that only contains the fully exposed layer.In one embodiment, the acquisition rate can be increased by only taking images of a partial area of ​​the powder material layer or the working area (Region Of Interest; ROI).

[0015] Alternatively, multiple composite images can be created from the captured images of the powder material layer. This is particularly important because one captured image may depict only an unexposed powder material layer, another may depict only the fully exposed powder material layer, and perhaps a third image may depict only a spatter pattern.

[0016] Preferably, in a further step, one or more composite images or composite images of partial regions can be generated from the recorded images of the powder material layer.

[0017] In one embodiment, the powder material can be exposed to energy beams while the application device is located within the work area. This avoids further downtime and thus accelerates the process, which in turn leads to more cost-effective component production.

[0018] In one embodiment, the work area detection device may continuously capture images of the powder material layer, in particular at a capture frequency of 0.01 Hz to 100 Hz, and more preferably at a capture frequency of 0.2 Hz to 5 Hz.

[0019] Advantageously, the images can be taken synchronously with the movement of the application device, preferably an image is taken every 1 mm to 50 mm of travel of the application device.

[0020] In one embodiment, the work area detection device can select locally different sub-areas from a sequence of multiple recorded images for the powder material layer to generate one or more composite images or composite images of sub-areas. Advantageously, the image with the fewest or no process emissions can be selected or generated from a sequence of images.

[0021] In a further embodiment, multiple workspace detection devices can be used to monitor the powder material layer or the workspace. In the case of multiple cameras, the images can be combined both temporally and spatially.

[0022] In particular, an algorithm can calculate each composite image such that each pixel is the result of a calculation rule whose parameters include, among other things, the pixel values ​​at the same position from all acquired images for this powder material layer. The calculation rule preferably selects the darkest or brightest pixel from the sequence of pixels. Selecting the darkest pixel ensures that only pixels of the powder material layer or the work area that are not exposed to the energy beam(s) at the time of image acquisition are used.

[0023] In one embodiment, the application device can have at least one marking for determining the position of the application device by means of the work area detection device. The marking serves as a marker for cutting out parts of an image since these are unusable. This preferably refers to those parts of the image which at least partially encompass the application device. The area beneath the application device, i.e. the powder bed, can only be shown by another image. Thus, the at least one marking on the application device serves to indicate unusable areas or locations in the images. The position of the application device can be determined by storing the position at which the application device was located when the image was taken. This position can then be calculated back to a position in the image and the area can be cut out.In addition, the position of the application device at a time of image acquisition could also be queried via the control system, or the control system could trigger the image acquisition in such a way that an image is always taken when the application device has moved the next path increment.

[0024] In a further embodiment, when processing the recorded images of the powder material layer, an algorithm can take into account the position of the application device and the recorded images can be further processed.

[0025] In one embodiment, images can be taken of both the powder material layer already exposed by the energy beams and the powder material layer above it that is still to be exposed, and a composite image of both a powder material layer already exposed by the energy beams and a powder material layer that is still to be exposed can be generated.

[0026] In one embodiment, during the application of the powder material layer in the work area by moving the application device, in particular by horizontal movement, the energy beams can solidify the powder material both before and after the application device. Advantageously, this allows both the current powder material layer, which has not yet been completely applied, and the previous powder material layer to be exposed to the energy beams.

[0027] In particular, a brightness adjustment can be performed at the transition areas between two images, and preferably the brightness of the images can be adjusted. This improves the image quality at said transition areas between two images.

[0028] Preferably, the manufacturing device can have a build space or a build chamber, and the workspace detection device is fixed to this build space, preferably attached to the ceiling of the build space. Furthermore, the manufacturing device can have multiple workspace detection devices. This is particularly advantageous when the field of view of one workspace detection device is not capable of detecting the entire workspace. The workspace can then be divided into sub-areas that can be monitored by multiple workspace detection devices.

[0029] The object is also achieved by providing a manufacturing device for producing at least one component layer by layer from a plurality of powder material layers of a powder material arranged in a layer sequence in a working area of ​​the manufacturing device by locally selective solidification of the powder material arranged in the working area.The manufacturing device comprises at least one beam generating device configured to generate at least one energy beam, at least one scanner device configured to displace the at least one energy beam in the work area, an application device for applying a powder material layer to the work area, a work area detection device configured to detect the work area, and a control device configured to carry out the method for monitoring a powder material layer of a manufacturing device.

[0030] In one embodiment, the application device can have at least one marking for determining the position of the application device by means of the working area detection device; preferably, the position of the application device is determined in the image or in the output signal of the working area detection device.

[0031] In a further embodiment, the at least one marking for determining the position of the application device contains a binary code, wherein the marking is preferably a barcode, QR code, or ArUco marker. The binary code serves to identify objects by the application device. The marking can also be an engraving, hole, edge, or similar. It simply needs to be image-recognizable.

[0032] In particular, the manufacturing device can have a construction space, and wherein the work area detection device is fixed to this construction space, preferably to the ceiling of the construction space.

[0033] Other features and aspects of this disclosure will become apparent from the following description and the accompanying drawings. Brief description of the drawings

[0034] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the drawings: Fig. 1 a schematic representation of an embodiment of a manufacturing device for producing at least one component, Fig. 2 a schematic representation of an embodiment of a working area of ​​a manufacturing device for producing at least one component, Fig. 3 a sequence of five process-parallel images of the powder material layer during exposure by means of energy beams, and Fig. 4 a composite image without disturbing influences such as the application device or process emissions. Detailed description

[0035] The following is a detailed description of exemplary embodiments of the present disclosure. The exemplary embodiments described herein and illustrated in the drawings are intended to teach the principles of the present disclosure and to enable one of ordinary skill in the art to implement and use the present disclosure in a variety of environments and for a variety of applications. Therefore, the exemplary embodiments are not intended to be, and should not be considered, a limiting description of the scope of patent protection. Rather, the scope of patent protection is to be defined by the appended claims.

[0036] Fig. 1 shows a schematic representation of an embodiment of a manufacturing device 1 for producing at least one component 19 or a three-dimensional object. The manufacturing device 1 comprises a build space 3 or a process chamber and a control unit 5. The control unit 5 has a data storage medium for storing control programs. In this embodiment, the manufacturing device 1 has three scanner units 9a, 9b, 9c, each deflecting an energy beam 11a, 11b, 11c generated by at least one beam generation unit 10a, 10b, 10c. For example, each scanner unit 9a, 9b, 9c for an energy beam or laser beam can comprise one scanner mirror (not shown) rotatable in two directions or two scanner mirrors rotatable in one direction. For example, the scanner unit 9a, 9b, 9c can comprise a galvanometer scanner.Alternatively, the electron beam scanner unit 9a, 9b, 9c may comprise several pairs of electrodes between which an electric field may be applied to deflect the electron beam.

[0037] The production device 1 further comprises a substrate plate 13, which is arranged beneath the scanner units 9a, 9b, 9c and onto which a building material 15, such as a powder or a powder bed, is applied layer by layer. For this purpose, the substrate plate 13 is adjusted in the Z-direction, i.e. in the direction of increasing distance from the scanner units 9a, 9b, 9c, by a desired distance and then a new layer or layers of powder material are applied using an application device 17, such as a coater module or a powder slide. Scrapers, blades or rollers, for example, can also be considered as application devices 17. In this specific case, the scanner units 9a, 9b, 9c are suitable for directing their respective energy beams 11a, 11b, 11c over the entire powder material 15. Thus, in this embodiment, the entire powder material surface forms a common working plane 18 orThis represents a working area in which the energy beams 11a, 11b, 11c can solidify the powder material 15. After the respective uppermost layer of powder material has solidified, the substrate plate 13 can be moved again in the Z direction, and a new layer of powder material is applied via the application device 17 in order to produce a component or three-dimensional object 19 layer by layer.

[0038] The build chamber 3 is gas-tight and includes a gas inlet 21 and a gas outlet 23. Usually, there are one or more secondary inlets to support a laminar primary flow and prevent splashes and smoke from spreading to undesired locations (not shown). The build chamber 3 can be filled with an inert gas, e.g., nitrogen or argon, via the gas inlet 21 to prevent oxidation of the powder material 15. Together with the gas outlet 23, a uniform protective gas flow can also be formed over the powder material 15 to remove condensates, powder particles, and other particles that are ejected into the atmosphere during solidification with energy beams, thus reducing potential interference with the beam 11a, 11b, 11c. The gas outlet 23 can also be used to evacuate the build space 3 so that electron beams can be used as energy beams 11a, 11b, 11c.For this purpose, the installation space 3 must be made vacuum-tight.

[0039] The control unit 5 can also have a data interface, via which, for example, control programs can be imported. When executing a control program via a control interface, the control unit 5 can perform all steps necessary for layer-by-layer additive manufacturing on the device, such as activating or deactivating energy beams 11a, 11b, 11c, deflecting them with the scanner units 9a, 9b, 9c, adjusting the substrate plate 13 along the Z-axis, or triggering a powder material application using the application device 17.

[0040] The manufacturing device 1 also includes a workspace detection device 12, such as a camera, which is configured to capture images of the powder material layer. In the present embodiment, the workspace detection device 12 is mounted on the ceiling of the build space 3, preferably directly above the work plane 18.

[0041] Fig. 2 shows a schematic representation of an embodiment of a working area or a working plane 18 of a manufacturing device 1 for producing the at least one component 19. In the Fig. 2 shows a top view of the work plane 18 or the work area. The work plane 18 contains, on the one hand, the powder material 15 and, on the other hand, at least one manufactured component 19 or one component to be manufactured. In the example shown, two components 19 are shown being manufactured.

[0042] Furthermore, the application device 17 moves across the working plane 18, applying a new layer of powder material. In this example, three markings 25 are located on the upper surface, or generally fixed to the application device 17, which can be detected by the working area detection device 12.

[0043] Fig. Figure 3 shows a sequence of five process-parallel images of the powder material layer during exposure of the powder material layer using the energy beams 11a, 11b, 11c. The disruptive process influences in the images shown, such as process emissions such as splashes and smoke, and the just-exposed area on the powder material layer in the working plane 18, are clearly visible. This leads to unsatisfactory images in which the powder material 15 of the powder material layer as well as the component 19 are partially obscured by the process influences, thus at least complicating the evaluation of the images.

[0044] Fig. Figure 4 shows a composite image without any interfering influences, such as the application device 17 or process emissions. It is readily apparent that the entire working plane 18, including powder material 15 and components 19, is visible without any interfering influences.

[0045] It is expressly understood that all features disclosed in the description and / or the claims are intended to be disclosed separately and independently of one another for the purpose of original disclosure and for the purpose of limiting the claimed invention, regardless of the composition of the features in the embodiments and / or the claims. It is expressly understood that all ranges of values ​​or indications of groups of units disclose every possible intermediate value or intermediate value for the purpose of original disclosure and for the purpose of limiting the claimed invention, in particular as limits of ranges of values.

[0046] Although the preferred embodiments of this invention have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims. List of reference symbols 1 manufacturing device 3 Build space or build chamber 5 Control unit 9a, 9b, 9c Scanner unit 10a, 10b, 10c Beam generation unit 11a, 11b, 11c Energy beam 12 Work area detection device 13 Substrate plate 15 Powder material or building material 17 Application device 18 working level 19 Component or three-dimensional object 21 Gas inlet 23 Gas outlet 25 Marking QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 732 890 A2

[0002] DE 10 2018 218 991 A1

[0007]

Claims

[1] Method for monitoring a powder material layer of a manufacturing device (1), wherein the manufacturing device (1) is designed to produce at least one component (19) layer by layer from a plurality of powder material layers of a powder material (15) arranged in a layer sequence in a working area of ​​the manufacturing device (1) by locally selective solidification of the powder material (15) arranged in the working area by means of energy beams (11a, 11b, 11c), the method comprising the following steps: a) applying a layer of powder material in the working area by moving an application device (17), b) taking several images of the entire or a partial area of ​​the powder material layer by means of a working area detection device (12), while the powder material (15) arranged in the working area is exposed by means of energy beams (11a, 11b, 11c) or while the application device (17) is located within the working area, and c) Processing the captured images of the powder material layer. [2] Method according to claim 1, wherein in a further step one or more composite images or composite images of partial areas are generated from the recorded images of the powder material layer. [3] Method according to claim 1 or 2, wherein the exposure of the powder material (15) is carried out by means of energy beams (11a, 11b, 11c) while the application device (17) is located within the working area. [4] Method according to one of claims 1 to 3, wherein the working area detection device (12) continuously records images of the powder material layer, in particular with a recording frequency of 0.01 Hz to 100 Hz and more preferably with a recording frequency of 0.2 Hz to 5 Hz. [5] Method according to one of claims 1 to 4, wherein the images are taken synchronously with the movement of the application device (17), preferably an image is taken every 1 mm to 50 mm of travel of the application device (17). [6] Method according to one of claims 2 to 5, wherein the working area detection device (12) selects locally different partial areas from a sequence of several recorded images for the powder material layer to generate one or more composite images or composite images of partial areas. [7] A method according to claim 6, wherein an algorithm calculates each composite image such that each pixel is the result of a calculation rule whose parameters are, inter alia, the pixel values ​​at the same position from all acquired images for that powder material layer, wherein the calculation rule preferably selects the darkest or the lightest pixel from the sequence of pixels. [8] Method according to one of claims 1 to 7, wherein the application device (17) has at least one marking (25) for determining the position of the application device (17) by means of the working area detection device (12). [9] Method according to claim 8, wherein when processing the recorded images of the powder material layer, an algorithm takes into account the position of the application device (17) and the recorded images are further processed. [10] Method according to one of claims 1 to 9, wherein images are taken both of the powder material layer already exposed by the energy beams (11a, 11b, 11c) and of the powder material layer still to be exposed lying thereover. [11] Method according to one of claims 1 to 10, wherein during the application of the powder material layer in the working area by moving the application device (17), the energy beams (11a, 11b, 11c) can solidify the powder material (15) both before and after the application device (17). [12] Method according to one of claims 1 to 11, wherein a brightness adjustment is carried out at the transition areas of two images, and wherein preferably the brightness of the images can be adjusted. [13] Method according to one of claims 1 to 12, wherein the manufacturing device (1) has a construction space (3), and wherein the working area detection device (12) is fixed to this construction space (3), preferably to the ceiling of the construction space (3). [14] Manufacturing device (1) for producing at least one component (19) layer by layer from a plurality of powder material layers of a powder material (15) arranged in a layer sequence in a working area of ​​the manufacturing device (1) by locally selective solidification of the powder material (15) arranged in the working area, comprising at least one beam generating device (10a, 10b, 10c) which is arranged to generate at least one energy beam (11a, 11b, 11c), at least one scanner unit (9a, 9b, 9c) which is arranged to displace the at least one energy beam (11a, 11b, 11c) in the working area, an application device (17) for applying a layer of powder material to the working area, a work area detection device (12) configured to detect the work area, and a control unit (5) which is configured to carry out a method according to one of claims 1 to 13. [15] Manufacturing device (1) according to claim 14, wherein the application device (17) has at least one marking (25) for determining the position of the application device (17) by means of the working area detection device (12), preferably the position of the application device (17) is determined in the image or in the output signal of the working area detection device (12). [16] Manufacturing device (1) according to claim 15, wherein the at least one marking (25) for determining the position of the application device (17) contains a binary coding, wherein the marking (25) is preferably a barcode, QR code or ArUco marker. [17] Manufacturing device (1) according to one of claims 14 to 16, wherein the manufacturing device (1) has a construction space (3), and wherein the working area detection device (12) is fixed to this construction space (3), preferably to the ceiling of the construction space (3).

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