Method for monitoring a powder material layer of a production device, and production device

Abstract

The invention relates to a method for monitoring a powder material layer of a production device (1), wherein the production 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 chronologically successively in a working region (18) of the production device (1) by locally selectively solidifying the powder material (15) arranged in the working region (18) by means of energy beams (11a, 11b, 11c), wherein the method comprises the following steps: applying a powder material layer in the working region by moving an application device (17), capturing a plurality of images of different sub-regions of the powder material layer by means of a plurality of working region detection devices (12), and processing the images of the powder material layer captured by the plurality of working region detection devices (12).

Description

[0001] DESCRIPTION

[0002] Method for monitoring a powder material layer of a manufacturing device, and a manufacturing device

[0003] Technical area

[0004] The invention relates to a method for monitoring a powder material layer of a manufacturing device, wherein the manufacturing device is set up 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 a manufacturing device.

[0005] Background of the Revelation

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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. In the case of 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.

[0012] In conventional manufacturing devices, 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 devices therefore accept an interruption in component production in order to take an optical image of the working layer of the powder bed and check it for 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.

[0013] The present invention is based on the object of avoiding such delays and interruptions in the production of components using powder-bed processes due to the monitoring of a layer of powder material. Furthermore, as plants become increasingly larger, the construction areas are also becoming larger, so that an ever-increasing area must be monitored. This leads to increased costs and effort.

[0014] 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.

[0015] Thus, the present disclosure is directed, at least in part, to improving upon or entirely overcoming one or more aspects of prior systems.

[0016] Summary of Revelation

[0017] 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.

[0018] The object is achieved in particular by a method for monitoring a powder material layer of a manufacturing device, wherein the manufacturing device is set up to produce at least one component layer by layer from a plurality of powder material layers of a powder material arranged sequentially in a layer sequence in a work area of ​​the manufacturing device by locally selective solidification of the powder material arranged in the work area by means of energy beams, wherein the method comprises the following steps: applying a powder material layer in the work area by moving an application device, taking a plurality of images of different partial areas of the powder material layer by means of a plurality of work area detection devices, and processing the images of the powder material layer taken by the plurality of work area detection devices.

[0019] Advantageously, this innovative method can shorten or even completely eliminate the downtime between the movement of the application device and the exposure of the powder material layer. Furthermore, by capturing images of different sub-areas of the powder material layer using multiple work area detection devices, such as a camera, and processing the images of the powder material layer captured by the multiple work area detection devices, disruptive influences on the images, such as the application device, can be cut out or eliminated. This is possible because, while the application device is moving across the work area, images can be captured of sub-areas to which the application device has already applied new powder.For example, different parts of several images can be combined into one image, whereby this combined image does not show the application device. However, it is also possible to differentiate between an image that only contains freshly coated areas and an image that only contains the fully exposed layer. By only capturing images of a partial area of ​​the powder material layer or the work area (region of interest; ROI), the capture rate can be increased. On the other hand, costs can be saved by capturing images of smaller partial areas, since smaller cameras are cheaper than one large camera that can cover the entire work area.

[0020] In a further embodiment, a further step involves generating a composite image of the work area, consisting of the different sub-areas of the powder material layer, from the images captured by the multiple work area detection devices. Alternatively, the work area detection devices consist of cameras or line scan cameras.

[0021] Preferably, the manufacturing device has a construction space, wherein the work area detection devices are fixed to this construction space, preferably to the ceiling of the construction space.

[0022] According to a further embodiment, the working area detection devices are aligned such that the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices at least partially overlap.

[0023] Alternatively, the images of the partial areas of the powder material layer captured by the multiple work area detection devices are first intrinsically calibrated and their distortion corrected, whereby the checkerboard method of Zhang is preferably used for the intrinsic calibration.

[0024] In a further embodiment, the images of the partial regions of the powder material layer recorded by the plurality of work area detection devices are extrinsically calibrated in a further step such that the images are perspectively corrected, subsequently aligned with one another and combined into one image in a final step.

[0025] Preferably, at least one marking is arranged in a common overlap region of the partial regions of the powder material layer, which marking is configured to align the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices with one another.

[0026] Advantageously, the at least one marking in the common overlap region of the partial regions of the powder material layer is used in such a way that the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices are combined to form one image.

[0027] In one embodiment, the at least one marking comprises a hole, milled recess, structure in the work area, structure in the powder material layer, or binary coding, wherein the marking is preferably a barcode, QR code, or ArUco marker. Alternatively, a brightness adjustment and / or contrast correction can be performed at the transition areas between two images, preferably adjusting the brightness of the images.

[0028] In one embodiment, at least one marking is arranged in a common overlap region of the partial regions of the powder material layer, wherein a drift compensation of the working area detection devices is carried out by means of the at least one marking, preferably comprising the following steps: a) determining the positioning of the at least one marking by means of an image processing algorithm, b) determining the homography transformation between the working area detection devices by means of the determined positions of the at least one marking, and c) recalculating the extrinsic calibration parameters of the working area 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 unit configured to displace the at least one energy beam in the work area, an application device for applying a layer of powder material to the work area, a plurality of work area detection devices configured to detect the work area, and a control unit configured to carry out the method for monitoring a layer of powder material of a manufacturing device.

[0030] Advantageously, the working area detection devices are aligned such that the images of the partial areas of the powder material layer recorded by the plurality of working area detection devices at least partially overlap.

[0031] In one embodiment, the images of the partial regions of the powder material layer captured by the multiple work area detection devices include at least one marking in a common overlap area. In one embodiment, the powder material can be exposed using energy beams while the application device is located within the work area. This allows further downtime to be avoided and thus accelerates the process, which in turn leads to more cost-effective component production.

[0032] Advantageously, the images can be taken synchronized with the movement of the application device.

[0033] 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.

[0034] 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.

[0035] Other features and aspects of this disclosure will become apparent from the following description and the accompanying drawings.

[0036] Short description of the drawings

[0037] 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:

[0038] Fig. 1 is a schematic representation of an embodiment of a manufacturing device for producing at least one component,

[0039] Fig. 2 is a schematic representation of an embodiment of a work area of ​​a manufacturing device for producing at least one component, and Fig. 3 is an embodiment of a method for providing a composite image of two partial areas of the work area.

[0040] Detailed description

[0041] 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.

[0042] Figure 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 scanning unit 9a, 9b, 9c for an electron beam may comprise several pairs of electrodes between which an electric field may be applied to deflect the electron beam.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The manufacturing device 1 also comprises two work area detection devices 12, such as cameras, which are configured to capture images of the powder material layer. In the present embodiment, the work area detection devices 12 are mounted on the ceiling of the build space 3, preferably directly above the work plane 18.

[0047] Figure 2 shows a schematic representation of an exemplary embodiment of a work area or a work plane 18 of a manufacturing device 1 for producing the at least one component 19. Figure 2 shows the work plane 18 or the work area in a plan view. The work plane 18 contains, on the one hand, the powder material 15 and / or, on the other hand, the underlying, at least one manufactured or to-be-manufactured component 19.

[0048] In addition, several markers 25, in this embodiment four markers 25 in the form of ArUco markers, are applied outside the work area 18. The markers 25 serve as a reference for the work area detection devices 12, according to which the images generated by the work area detection devices 12 can be aligned with each other.

[0049] Furthermore, Figure 2 shows two so-called field of view regions 30, which indicate which regions can be detected by a respective work area detection device 12. In this embodiment, a first work area detection device 12 can detect the left field of view region 30, and a second work area detection device 12 can detect the right field of view region 30.

[0050] The two field of view areas 30 have a common overlap area 32, meaning that in this overlap area 32, several work area detection devices 12 can detect the same area or work area 18. The markings 25 are arranged in this common overlap area 32 of the work area detection devices 12, which make it possible to align the images recorded by the work area detection devices 12 with one another.

[0051] Figure 3 shows an embodiment of a method for providing a composite image of two sub-areas of the workspace 18. In a first step, each of the two workspace detection devices 12 acquires an image of the two sub-areas of the workspace 18. Each workspace detection device 12 acquires an image of its respective field of view 30. This results in a left output image and a right output image. In a second step, the intrinsic calibration of the two output images takes place. In this embodiment, the intrinsic calibration is carried out using the so-called checkerboard method by Zhang (https: / / www.researchgate.net / publication / 303233579 Zhang's Camera Calibration Algorithm In-Depth Tutorial and Implementation; “Zhang's Camera Calibration Algorithm: In-Depth Tutorial and Implementation”, May 2016, DOE10.13140 / RG.2.1.1166.1688 / 1, Report number: HGB16-05).In addition, the distortion of the two images is corrected. In a third step, the processed images are extrinsically calibrated so that the perspective distortions are corrected and then aligned. In a fourth and final step, the images are combined into a single image.

[0052] 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.

[0053] 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.

[0054] List of reference symbols

[0055] 1 manufacturing device

[0056] 3 Build space or build chamber

[0057] 5 Control unit 9a, 9b, 9c Scanner unit

[0058] 10a, 10b, 10c beam generation unit

[0059] 11a, 11b, 11c Energy beam

[0060] 12 Work area detection device

[0061] 13 Substrate plate 15 Powder material or building material

[0062] 17 Application device

[0063] 18 Working level or work area

[0064] 19 Component or three-dimensional object

[0065] 21 Gas inlet 23 Gas outlet

[0066] 25 Marking

[0067] 30 field of view areas

[0068] 32 common overlap area

Claims

Claims 1. A 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 in a layer sequence in a work area (18) of the manufacturing device (1) by locally selective solidification of the powder material (15) arranged in the work area (18) by means of energy beams (11a, 11b, 11c), the method comprising the following steps: Applying a layer of powder material in the working area (18) by moving an application device (17), taking several images of different partial areas of the powder material layer by means of several working area detection devices (12), and Processing the images of the powder material layer captured by the plurality of work area detection devices (12).

2. The method according to claim 1, wherein in a further step a composite image of the working area (18) consisting of the different partial areas of the powder material layer is generated from the images recorded by the plurality of working area detection devices (12).

3. Method according to claim 1 or 2, wherein the work area detection devices (12) consist of cameras or line scan cameras.

4. Method according to one of claims 1 to 3, wherein the manufacturing device (1) has a construction space (3), and wherein the work area detection devices (12) are fixed in position to this construction space (3), preferably on the ceiling of the construction space (3).

5. The method according to any one of claims 1 to 4, wherein the working area detection devices (12) are aligned such that the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices (12) at least partially overlap.

6. The method according to any one of claims 1 to 5, wherein the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices (12) are first intrinsically calibrated and their distortion is corrected, wherein the checkerboard method of Zhang is preferably used for the intrinsic calibration.

7. The method according to claim 6, wherein the images of the partial regions of the powder material layer recorded by the plurality of work area detection devices (12) are extrinsically calibrated in a further step such that the images are perspectively corrected, subsequently aligned with one another and combined into one image in a final step.

8. Method according to one of claims 1 to 7, wherein in a common overlap region (32) of the partial regions of the powder material layer at least one marking (25) is arranged, which is configured to align the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices (12) with each other.

9. The method according to claim 8, wherein the at least one marking (25) in the common overlap region (32) of the partial regions of the powder material layer is used in such a way that the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices (12) are combined to form one image.

10. The method according to claim 8 or 9, wherein the at least one marking (25) contains a bore, milling, structure in the working area, structure in the powder material layer or binary coding, wherein the marking (25) is preferably a barcode, QR code or ArUco marker.

11. Method according to one of claims 1 to 10, wherein a brightness adjustment and / or a contrast correction is carried out at the transition areas of two images, and wherein preferably the brightness of the images can be adjusted.

12. Method according to one of claims 6 to 11, wherein in a common overlap region (32) of the partial regions of the powder material layer at least one marking (25), wherein a drift compensation of the working area detection devices (12) is carried out by means of the at least one marking (25), preferably comprising the following steps: a) determining the positioning of the at least one marking (25) by means of an image processing algorithm, b) determining the homography transformation between the working area detection devices (12) by means of the determined positions of the at least one marking (25), and c) recalculating the extrinsic calibration parameters of the working area detection devices (12).

13. A 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 chronologically in a work area (18) of the manufacturing device (1) by locally selective solidification of the powder material (15) arranged in the work area (18), comprising at least one beam generating device (10a, 10b, 10c) configured to generate at least one energy beam (11a, 11b, 11c), at least one scanner unit (9a, 9b, 9c) configured to displace the at least one energy beam (11a, 11b, 11c) in the work area, an application device (17) for applying a powder material layer to the work area, a plurality of work area detection devices (12) configured to detect the work area, and a control unit (5),which is designed to carry out a method according to one of claims 1 to 12., 14. Manufacturing device (1) according to claim 13, wherein the work area Detection devices (12) are aligned such that the images of the partial regions of the powder material layer recorded by the plurality of working area detection devices (12) at least partially overlap.

15. Manufacturing device (1) according to claim 13 or 14, wherein the images of the partial regions of the powder material layer recorded by the plurality of work area detection devices (12) have at least one marking (25) in a common overlap region (32).

Images