Method for setting up and adjusting a building plate

Abstract

Method for setting up and adjusting a build plate in a laser sintering or laser melting device (1), in which powdery build material (3) is applied to a surface of a build plate (4) or an already solidified build material layer (25) and is selectively solidified by the action of radiation energy, in particular laser radiation, to produce a component (2), wherein, before the start of the build process, the build plate (4) is placed on a height-adjustable carrier (5) of the laser sintering or laser melting device (1), wherein the - the upward-facing surface of the building plate (4) is provided with an optical pattern (20) detectable by a camera device (21) before or after being placed on the support (5), - the building plate (4) provided with the pattern (20) is coated with building material (3) in the laser sintering or laser melting device (1) such that the surface of the building plate (4) is covered by a homogeneous layer of building material (25); - subsequently, by successively and stepwise lifting the carrier (5), the powder of the building material layer (25) is removed layer by layer by the coater (10), and at or after each removal of a layer, the remaining building material layer (25) is captured by the camera device (21); - Continue the layer-by-layer removal of powder layers until the defined pattern (20) applied to the upward-facing surface of the building plate (4) is visible through a residual layer of building material (26) by the camera device (21); - automatic detection of whether the translucent pattern is not fully or uniformly visible, then automatic readjustment of the horizontal alignment of the build plate (4) by a multi-spindle drive (30) of the carrier (5) of the laser sintering or laser melting device (1), with which a horizontal alignment of the carrier and thus also of the build plate (4) resting on it can be adjusted; - Starting the construction process by solidifying the residual building material layer (26) and / or a further layer of building material applied to it, after the camera device (21) has detected the defined pattern (20) visible through the residual building material layer (26).

Description

[0001] The invention relates to a method for setting up and adjusting a build plate in a laser sintering or laser melting device with the further features of claim 1. An additive manufacturing process in a laser sintering or laser melting device is carried out by applying powder-like building material to the surface of a build plate or to an already solidified layer of building material and selectively and locally solidifying it to produce a component by the action of radiation energy, in particular laser radiation, wherein, before the start of the manufacturing process, the build plate is placed on a height-adjustable carrier of the laser sintering or laser melting device and, if necessary, fixed there.

[0002] Adjusting a building panel in such a device is relatively complex and requires great care to ensure that, firstly, the upward-facing surface of the panel is perfectly flat and horizontal for the coating process. Secondly, the exact height of the panel's surface relative to the coating device moving back and forth above it must be precisely determined. The coating and hardening of the first layer on the panel is particularly critical, as an excessively thick first layer of building material can prevent sufficient bonding with the panel's surface, leading to partial delamination. To prevent such delamination, the panel's surface must be precisely leveled before the construction process begins.

[0003] Currently, the insertion and adjustment of the build plate are done manually. An operator places the build plate onto a height-adjustable support of the device and, if necessary, secures it there, for example, using a clamping system. The build plate is then moved from below towards the coating device. The "zero position" at which the coating device, which moves back and forth above the build plate, makes contact with the surface of the build plate is then determined. This mechanical contact can lead to minor damage to the surface of the build plate, especially when hard coating blades are used.

[0004] EP 1 048 441 A1 discloses a method for calibrating a device for manufacturing a three-dimensional object and a calibration device.

[0005] EP 0 792 481 B1 discloses a method and a device for calibrating a control for deflecting a laser beam.

[0006] DE 10 2010 006 939 A1 discloses a device for producing three-dimensional models.

[0007] The invention is based on the objective of providing a method for adjusting the height of a build plate and, if necessary, for readjusting the plane alignment of the build plate, which can be carried out automatically and delivers precise adjustment results without being subject to the disadvantages of the prior art described above. In particular, the method should be feasible, if necessary, by automatic loading and placement devices of selective laser melting (SLM) devices or selective laser sintering (SLS) devices.

[0008] This problem is solved by the features of claim 1, according to which a patterned build plate is inserted into the device, covered with a layer of building material of a certain thickness, and then the layer of building material is successively peeled away until the pattern applied to the surface of the build plate is recognized by a camera with connected image recognition software through a residual layer of building material remaining on the surface of the build plate. In this initial state, only the very thin layer of building material of 20–50 µm remains on the build plate; this layer, or a further applied thin layer, then serves as the first layer, which is solidified within an additive manufacturing process and at least partially bonded to the surface of the build plate.

[0009] Such a process can be automated; in particular, it is possible to apply the pattern by exposing the build plate to light, melting its surface. A pattern formed by melting the build plate's surface has glossy areas, in contrast to the plate's typically matte surface, and is therefore easily recognizable by a camera with associated recognition software.

[0010] In principle, it is also possible to apply the pattern to the build plate, for example, by etching the surface or mechanically. In laser sintering or laser melting, the pattern can be applied to the build plate using the radiation energy source also employed in the build process, in particular a laser whose beam is guided over a scanner. This scanner then lasers a corresponding recognition pattern into the surface of the build plate in a process-controlled manner before the powder layer, which is to be removed layer by layer, is applied.

[0011] The removal of the building material layers to prepare for the pattern recognition process by the camera device is carried out using a building material coating assembly that moves horizontally above the build plate. This coating assembly thus serves both as a coater and as a layer reduction device. During the process, it reduces the applied building material layer to such an extent that the pattern applied to the build plate shows through the remaining layer. This ensures that there is a minimal distance, e.g., 20–50 µm, between the coating edge and the surface of the build plate. This process ensures that the coater itself does not touch the build plate, maintaining a minimum safety distance at all times.

[0012] The pattern extends at least partially to the edges and / or corners of the building panel. If the surface of the building panel is not supported level, the system automatically detects that the pattern is not fully or uniformly visible. In this case, a multi-spindle drive raises or lowers the support plate on which the building panel rests, re-leveling the surface of the building panel.

[0013] The described adjustment method can be particularly advantageously used in the context of fully automating a laser sintering or laser melting device. With an automated device, it is possible, for example, to automatically feed a build container to a selected device, position it within it, inertize it there, automatically set up the build plate (for which the method according to claim 1 is used), then automatically start and execute the build process, and after completion of the build process, automatically remove the build container from the machine and transport it to further stations. The laser sintering or laser melting device is then available again to receive further build containers in which a similarly automated process can be carried out.

[0014] The invention is explained in more detail with reference to an exemplary embodiment shown in the drawings. These show: Fig. 1 A schematic side view of a laser melting device in section; Fig. 2 a detailed view according to Fig. 1 with the carrier plate in an upper software end position; Fig. 3 a schematic top view of an uncoated but patterned build plate in the final software position; Fig. 4. A top view of a homogeneously coated building plate before the successive removal of the applied powder layer; Fig. 5 a schematic top view of the patterned building plate with a defined thin residual layer of building material through which the pattern is already visible again, i.e. in the initial process position; Fig. 6 A schematic top view of an uncoated building board with a different pattern.

[0015] Figure 1 schematically depicts a device 1 for the production of additively manufactured components 2, namely a laser sintering or laser melting device, with its essential components. In the device 1, powdered building material 3 is applied to the surface of a build plate 4, which is mounted on a support 5 within a build container 6 in a height-adjustable manner.

[0016] Radiation energy 8 is directed onto the powder layer via a laser 7 source and a scanner 9, causing the powder to melt and solidify.

[0017] The layer of building material is conveyed from a metering device 11 to the building container 6 by means of a reciprocating coating unit 10; excess building material can fall into an overflow container 12.

[0018] The build vessel 6, the metering device 11, and the overflow container 12 are arranged in a process chamber 13 in which a protective gas atmosphere can be maintained. The entire device is housed in a casing 14. All components are shown schematically only.

[0019] The procedure can only be carried out in accordance with Fig. 2. The carrier 5, with the build plate 4 mounted on it, is moved into an upper software end position, and a pattern 20 is laser-etched onto the surface of the build plate 4 using radiation energy 8, which can be directed onto the surface of the build plate 4 in a process-controlled manner by the scanner 9. The pattern 20 must be designed such that it is recognizable by a camera 21. A processor 22, in which image recognition software runs, is connected to the camera 21. The image recognition software and the processor 22 can, of course, also be part of a control system for the laser melting device 1.

[0020] The building plate 4, marked with pattern 20, is now coated with building material 3 in the device 1 such that the surface of the building plate 4 is completely covered by a homogeneous layer of building material 25. Subsequently, the carrier 5 is gradually lifted, and the powder of the building material layer 25 is peeled off layer by layer. After each layer is peeled off, the remaining layer of building material 25 is detected by the camera 21 to check whether the pattern 20 is already visible through the layer of building material. This process continues until the pattern 20 applied to the surface of the building plate 4 is detected by the camera 21 through a residual layer of building material 26. The building process is then started by solidifying the residual layer of building material 26 or by applying a further layer of building material to it, as soon as the camera 21 has detected the defined pattern 20 translucent through the residual layer of building material 26.

[0021] In Fig. Figure 3 schematically shows the pattern 20 applied to the surface of the building plate 4. Fig. Figure 4 shows the state in which the building plate 4, and thus the pattern 20, is completely covered by the building material layer 25. An edge area of ​​the support 5 is also covered by the building material layer 25.

[0022] Fig. Figure 5 schematically shows a very thin residual layer of building material 26, through which the pattern 20 is again optically recognizable. The camera device 21 is thus able to recognize the defined pattern 20 and signal to the processor of the device 1 that the build process can be started because the surface of the build plate 4 is in an optimized position for the start of the build process.

[0023] In Fig. Figure 6 shows that the pattern 20 can extend at least partially into the edge area or the corner areas of the building plate 4.

[0024] Figures 1 and 2 indicate that the carrier 5 is mounted in a height-adjustable manner by means of a multi-spindle drive 30. If the camera device 21 detects that the pattern 20 is not uniformly visible or is only partially visible, this indicates a tilt of the surface of the build plate 4 relative to the coater 10. In this case, the surface of the build plate 4 is automatically leveled by driving individual spindles of the multi-spindle drive 30.

[0025] Before the pattern is applied, the building plate 4 has a matte surface, at least in some areas. The pattern 20, in the form of glossy sections such as rectangles or diamonds, can be laser-etched into this matte surface. REFERENCE MARK LIST 1 Device 2 components 3 Building materials 4 building plates 5 carriers 6 construction containers 7 Laser 8 Radiant energy 9 scanners 10 coaters 11 Dosing device 12 overflow containers 13th Trial Chamber 14 Housings v. 1 20 samples 21 Camera device 22 processor 25 Building material layer 26 residual building material layer 30 multi-spindle drive

Claims

Method for setting up and adjusting a build plate in a laser sintering or laser melting device (1), in which powdery build material (3) is applied to a surface of a build plate (4) or to an already solidified build material layer (25) and is selectively solidified by the action of radiation energy, in particular laser radiation, to produce a component (2), wherein, before the start of the build process, the build plate (4) is placed on a height-adjustable carrier (5) of the laser sintering or laser melting device (1), wherein the upward-facing surface of the build plate (4) is provided with an optical pattern (20) detectable by a camera device (21) before or after being placed on the carrier (5), and the build plate (4) provided with the pattern (20) is coated with build material (3) in the laser sintering or laser melting device (1) such that the surface of the build plate (4) is covered by a homogeneous build material layer (25);- Subsequently, by successively and stepwise raising the carrier (5), the powder of the build material layer (25) is removed layer by layer by the coater (10), and the remaining build material layer (25) is captured by the camera device (21) during or after each removal of a layer; - Continuation of the layer-by-layer removal of powder layers until the defined pattern (20) applied to the upward-facing surface of the build plate (4) is recognizable by the camera device (21) through a residual build material layer (26); - Automatic detection of whether the translucent pattern is not completely or uniformly visible, then automatic readjustment of the horizontal alignment of the build plate (4) by a multi-spindle drive (30) of the carrier (5) of the laser sintering or laser melting device (1), with which a horizontal alignment of the carrier and thus also of the build plate (4) resting on it can be adjusted;- Starting the construction process by solidifying the residual building material layer (26) and / or a further layer of building material applied to it, after the camera device (21) has detected the defined pattern (20) translucent through the residual building material layer (26). Method according to claim 1, wherein the layer-by-layer peeling of the building material layer (25) continues until the remaining building material residue layer (26) has a layer thickness of 20 - 50 µm. Method according to claim 1 or 2, wherein the pattern (20) is applied by exposing the build plate (4) while melting the surface of the build plate (4). Method according to claim 1 or 2, wherein the pattern (20) is applied to the building plate (4) by etching or mechanical treatment of its surface. Method according to claim 3, wherein the exposure of the build plate (4) in the laser sintering or laser melting device (1) is carried out by the radiation energy source used in the build process. Method according to one of the preceding claims, wherein the peeling off of the building material layer (25) for the preparation of the pattern recognition process is carried out by the camera device (21) with a building material coating arrangement that can be moved horizontally over the building plate (4). Method according to one of the preceding claims, wherein the pattern (20) on the surface of the building plate (4) comprises a plurality of individual elements distributed over at least a partial area of ​​the surface of the building plate (4). Method according to one of the preceding claims, wherein the pattern (20) extends at least partially to the edge area and / or the corner areas of the building plate (4). Method according to one of the preceding claims, further comprising an automatic readjustment of the horizontal alignment of the build plate (4) by the multi-spindle drive (30) of the carrier (5) of the laser sintering or laser melting device (1), with which a horizontal alignment of the carrier (5) and thus also of the build plate (4) resting on it can be adjusted. Method according to one of the preceding claims, wherein the building plate (4) has a matte surface at least in certain areas before the pattern (20) is applied. Method according to one of the preceding claims, wherein the pattern (20) is formed by melted and thus shiny sections of the building plate (4). Method according to one of the preceding claims, wherein a processor (22) is connected to the camera device (21) in which image recognition software runs, which compares the pattern (20) of the build plate (4) detected by the camera device (21) with a stored reference pattern. Method according to claim 12, wherein the image recognition software checks whether the pattern (20) is fully and / or uniformly recognizable. The method according to claim 13, further comprising an automatic control of the multi-spindle drive (30) of the carrier (5) of the laser sintering or laser melting device (1) for horizontal readjustment of the carrier (5), provided that the image recognition software detects a non-planar orientation of the surface of the build plate (4) on the basis of the pattern (20) which is not fully or uniformly recognizable. Method according to one of the preceding claims, wherein the method for setting up and adjusting a build plate (4) in a laser sintering or laser melting device (1) is carried out in the course of an automatic setup procedure of the laser sintering or laser melting device (1), in which a build module is automatically docked to the laser sintering or laser melting device (1) and / or inerted, the build plate (4) is adjusted and set up and / or the build process is automatically started and / or after completion of the build process the build module is automatically removed from the laser sintering or laser melting device (1) and moved to a post-treatment and / or unpacking device for the finished component.

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