Device for additive manufacturing of products by means of a cleaning mode and method for additive manufacturing of a product by means of a cleaning mode

Abstract

The application relates to a device for additive manufacturing of products (2), in which a product is produced, layer by layer, by locally curing a resin that cures under light irradiation, having a resin container (3) for receiving a resin during the printing process, a print head (4) that can be moved in at least one vertical direction, a printing unit (5) for local application of light causing the local curing of the resin, to the resin held in the resin container (3) in order to produce the product (2), and a cleaning container (6) for receiving a cleaning medium. The application is characterised by a control device (7) that is designed, in a cleaning mode, firstly to move the print head (4) into the cleaning container (6), to execute a sequence of movements there, by means of which a flow is generated in the cleaning medium located there, and subsequently to move the print head (4) out of the cleaning medium. The application also relates to a corresponding method.

Description

[0001]P2024,0436 WO N 3 September 2025 Cleaning System -1 - Description DEVICE FOR THE ADDITIVE MANUFACTURING OF PRODUCTS BY MEANS OF A CLEANING MODE AND METHOD FOR THE ADDITIVE MANUFACTURING OF A PRODUCT BY MEANS OF A CLEANING MODE. The invention relates to the additive manufacturing of products, often referred to as 3D printing. This is a process in which three-dimensional objects are built up layer by layer according to a digital model. In a process called stereolithography (SLA), resin, hereinafter referred to as resin, is exposed layer by layer and thus cured in the areas reached by the light. Furthermore, the production of a product using the SLA process includes cleaning after layer build-up and, depending on the material, post-curing. The invention relates to a device that operates according to the SLA process, as well as such a process.The device comprises a resin container for receiving the resin during the printing process, a print head movable in at least one vertical direction, a printing unit for locally exposing the resin held in the resin container with light that causes the resin to cure locally in order to produce the product, and a cleaning container for receiving a cleaning medium. The term "resin" is used here to refer to a resin that cures under the influence of light. For the quality of the components manufactured by stereolithography, it is important that the components correspond to the digital model on which the printer was based. Therefore, it is important that any uncured resin residue adhering to the components is removed. Only in this way can high-quality surfaces be achieved and the tolerances maintained.Currently available systems for cleaning components manufactured using stereolithography are essentially based on two approaches. Either systems are used that generate a flow in the cleaning medium by means of stirrers, thus removing adhering resin residues from the components, or an ultrasonic bath is used in which cavitation bubbles are created on the surfaces by ultrasonic waves, which clean the components. However, stirring systems are insufficient when complex geometries or internal structures need to be cleaned. Ultrasonic baths, on the other hand, carry the risk of damaging fine structures and surfaces due to the intense action of the cavitation bubbles. Furthermore, ultrasonic waves cannot penetrate into fine holes. The object of the present invention is to provide a device for the additive manufacturing of products and a corresponding method in which the cleaning performance is improved.This problem is solved by a device of the type mentioned above, which is characterized in that it has a control device configured to first move the printhead into the cleaning medium in a cleaning mode, to perform a sequence of movements there that generates a flow, and subsequently to move the printhead out of the cleaning medium. With regard to a method, the solution to the problem is specified by independent method claim a. The features, properties, and embodiments described for the device or the method (P2024,0436 WO N 3 September 2025 Cleaning System -3) also apply accordingly to the method or the device. An advantage of the device according to the invention is that, in addition to external surfaces, internal structures such as channels are also completely cleaned. This is particularly important in applications where precision and reliability of the components are important.The cleaning mode according to the invention avoids these problems. Through repeated, for example, pulsating vertical and / or horizontal movement of the printhead, the cleaning agent is displaced from the printhead and the products adhering to it and begins to flow turbulently. In contrast to agitated cleaning systems, the highest flow velocities are generated at the surfaces of the products. This results in intensive cleaning even where it is actually needed. A special feature of the invention is therefore that it makes it possible to selectively create more intensive relative movement between the product and the cleaning medium. The proposed cleaning technique thus reaches areas that are difficult or impossible to clean with conventional methods, such as shaded areas, edges, through-holes, and fine structures.Particularly in the immediate vicinity of the printhead, good cleaning can be achieved where other methods are often insufficient. For example, the sequence of movements can comprise a repeated vertical up / down movement of the printhead over a maximum depth of the cleaning container, preferably a maximum of 80 mm, more preferably a maximum of 40 mm, and more preferably between 5 mm and 40 mm, and more preferably a maximum of 10 mm, or a repeated horizontal translational movement of the printhead over a maximum width of the cleaning container, preferably a maximum of 40 mm, more preferably between 5 mm and 40 mm, and more preferably a maximum of 10 mm, or a horizontal rotational movement, wherein the sequence of movements can also comprise a combination of the aforementioned movements.In particular, the control device can be configured to execute a sequence of movements within the cleaning tank, comprising repeated vertical up / down movements of the printhead. Thus, the printhead moves up and down multiple times within the cleaning tank without leaving the tank in between. This can also be an exclusively vertical up / down movement. The sequence of movements comprises, for example, a recurring movement with a period greater than 0.1 s, preferably less than 60 s, further preferably between 0.5 s and 60 s, and even more preferably between 0.5 s and 2 s. The improved cleaning process shortens the duration of the post-processing, leading to faster product completion. The more precise control of the cleaning process results in less stress on component surfaces, increasing the integrity and service life of the components.Ultimately, effective cleaning reduces the need for manual rework steps and minimizes component scrap, leading to cost savings. Furthermore, the P2024,0436 WO N 3 September 2025 cleaning system -5 - automates the cleaning process in the additive manufacturing equipment, enabling user-friendly operation that requires little technical expertise and reduces human error. According to a second aspect of the invention, at least one second cleaning container is provided, wherein the control device is configured to first move the pressure head into the first cleaning container to perform a first cleaning operation, and then move it into the second cleaning container to perform a second cleaning operation.The first and second cleaning containers can be arranged to be slidably positioned, so that the control unit only needs to move the printhead in the Z-direction via a drive, and the change from the first cleaning container to the second cleaning container is possible by moving the latter. It is particularly advantageous if the products are not formed directly at the printhead, but at a separating plate that is detachably coupled to the printhead. In this way, a quick change to the next print job is possible, since only the separating plate needs to be decoupled and the printhead coupled to a new, empty separating plate. According to a third aspect of the invention, the separating plate is decoupled from the printhead, and subsequently, printhead cleaning is carried out by moving the printhead without the separating plate in the cleaning medium. This can, in particular, clean the contact surfaces between the printhead and the separating plate.Furthermore, printhead cleaning can also simultaneously clean the product. P2024,0436 WO N 3 September 2025 Cleaning system -6 - Preferably, the movement is carried out as described above for cleaning the product. Decoupling takes place, in particular, within the cleaning medium. The separator plate with the product adhering to it can then be placed in the cleaning container during the movement of the printhead. Decoupling can take place after or before cleaning the product with the separator plate coupled to the printhead. It is also possible that no separate cleaning phase is provided for cleaning the product. The repeated movement of the printhead with the separator plate decoupled generates movement of the cleaning medium, which can also cause cleaning of the product placed in the cleaning medium. Thus, it is possible that no additional cleaning of the product is necessary with the separator plate coupled.The separating plate with the adhering products can then be re-coupled to the printhead. It is also possible for a separate cleaning phase to clean the product with the separating plate coupled to the printhead, before and / or after cleaning the contact surfaces and restoring the coupling. After cleaning is complete, the separating plate with the adhering product is removed from the cleaning container. This further development of the cleaning mode according to the invention takes into account that resin residues can accumulate between the printhead and the separating plate. The temporary decoupling of the separating plate and the printhead makes the contact surfaces accessible to the cleaning medium. P2024,0436 WO N 3 September 2025 Cleaning system -7 - In addition, further cleaning techniques, such as a stirred cleaner, can be used to create an additional flow of the cleaning medium in the cleaning container.Further advantageous embodiments of the invention are specified in the dependent claims. In particular, details of preferred motion parameters are given there. The invention is explained in more detail below with reference to exemplary embodiments. Figure 1 shows a first exemplary embodiment of a device for the additive manufacturing of products, Figure 2 shows a detailed representation of an arrangement with a print head and a cleaning container, Figures 3A to 3D show various stages of a cleaning process, and Figure 4 shows a second exemplary embodiment of a device according to the invention for the additive manufacturing of products with two cleaning containers. Figure 1 shows a device 1 designed as a 3D printer in a schematic representation. The 3D printer has a print head 4 which is coupled to a separating plate 8. The connection between the print head 4 and the separating plate 8 is detachable. For example, the separating plate 8 is held magnetically to the print head 4.The separating plate 8 is designed so that products can be built on its underside. For this purpose, the print head 4 P2024,0436 WO N 3 September 2025 Cleaning System -8 - is lowered into a resin container 3 with the separating plate 8 until the separating plate 8 is positioned just above the bottom of the resin container 3. At this point, there is still a thin layer of resin between the bottom of the resin container 3 and the separating plate 8. A printing unit 5 is arranged under the resin container 3. In this embodiment, this unit has a light source (not shown in Figure 1) and an LCD unit that acts like a digital mask. It consists of a flat panel, similar to that of a computer monitor. The LCD unit blocks or allows UV light to pass through, depending on which areas are to be exposed.The advantage of this setup, known as Masked Stereolithography Apparatus (MSLA), is that an entire layer can be exposed at once instead of point by point as in conventional stereolithography. This leads to faster printing speeds. When the release plate 8 is positioned at the bottom of the resin reservoir 3, exposure occurs, causing the first resin layer to harden and adhere to the release plate 8. The release plate 8 is then moved upwards a short distance, so that a thin layer of resin is again present between the bottom of the resin reservoir 3 and the first hardened layer. In this way, a three-dimensional product can be successively manufactured. When the product is fully assembled, in the 3D printing process of the illustrated embodiment, the resin container 3 together with the printing unit 5 is moved to the side, as indicated by the reference symbols 3' and 5'.In this way, the way is clear to move the printhead 4, including the optional separating plate 8 and the products 2 adhering to it, into a cleaning container 6 below in a subsequent cleaning process. In the cleaning process, which is described in more detail below, the products 2 are immersed in a cleaning medium located in the cleaning container 6. Figure 2 shows a more detailed, concrete representation of the arrangement with the printhead 4, which can be moved up and down by a linear guide 9, and a cleaning container 6. In this embodiment, optional agitators 10 are arranged in the cleaning container 6, which can additionally agitate the cleaning medium contained in the cleaning container 6. Figures 3A to 3D show various stages of a movement sequence according to the invention.The control unit 7 moves the printhead 4 with an attached product 2 into the cleaning container 6 until the product 2 is completely immersed in the cleaning medium. From this position, the printhead 4, controlled by the control unit 7, performs a repeated downward and upward movement, as shown in Figures 3B, 3C, and 3D. This generates a turbulent flow, whereby, unlike previous systems, the highest flow velocity is generated at the surface of the product 2. This results in the most intensive cleaning precisely where it is needed. This movement makes it possible to reach difficult-to-access areas and significantly improves the overall cleaning effect. The special feature lies in the fact that it makes it possible to selectively create a more intensive relative movement between the component and the cleaning medium. This leads to a far more effective cleaning, especially in the case of heavy P2024,0436 WO N 3.September 2025 Cleaning system -10 - accessible areas or complex geometries. This allows areas that were previously inaccessible to be specifically rinsed and washed with the cleaning medium. The additional agitator cleaners 10 support the cleaning process but are optional. It is also possible for the separating plate 8 in the cleaning container 6 to be decoupled from the printhead 4 and for cleaning of contact surfaces between the printhead 4 and the separating plate 8 to be carried out by moving the printhead 4 in the cleaning medium. Such cleaning of contact surfaces can be carried out as described above, in particular with the described sequence of movements. During printhead cleaning, the separating plate 8 is placed in the cleaning container 6. After cleaning, the separating plate 8 is coupled back to the printhead 4 and removed from the cleaning container 6.A separate cleaning phase for cleaning product 2 with separating plate 8 coupled to the printhead 4 can be provided before or after cleaning the contact surfaces. It is also possible that no separate cleaning phase for cleaning product 2 with separating plate 8 coupled is provided, since the turbulent flow generated for cleaning the contact surfaces can simultaneously clean product 2. Thus, in this case, the cleaning of product 2 takes place as described in Figures 3A to 3D, but with product 2 placed in the cleaning container 6, while the printhead 4 performs a sequence of movements to generate turbulent flow. In a further embodiment of this example, the cleaning process is designed such that after a first phase P2024,0436 WO N 3.September 2025 Cleaning System -11 - Following the cleaning process, a draining phase is performed in which the product is removed from the cleaning medium, and then the printhead with the product is immersed back into the cleaning medium. For example, the draining phase lasts between 10 and 120 seconds. This cleaning mode is advantageous when products have large cavities. These are first filled with the cleaning medium, during the draining phase the cleaning medium enriched with filament drains out, and then the cavity is refilled with the cleaning medium. In this way, even cavities that are not easily reached by a turbulent flow can be cleaned. The draining phase can be repeated several times if required due to the geometry of the product or the desired surface finish. A further improvement is achieved in a second embodiment according to Figure 4.A two-stage cleaning process is provided there, with a first cleaning stage aimed at removing coarse excesses of uncured resin. This step can be carried out in a solvent bath that may already be saturated with resin residues but is still sufficiently effective for coarse cleaning. In a second cleaning stage, a secondary wash is performed using a cleaner cleaning solution. In this stage, any remaining resin is removed. By first using a partially consumed solvent for the preliminary cleaning, the costs and frequency of solvent changes can be reduced. The two-stage process allows newer, less saturated solvents to remain in a clean state for longer. P2024,0436 WO N 3.September 2025 Cleaning system -12 - is maintained because it is used exclusively for the second cleaning stage to remove any remaining resin and ensure a high-quality surface finish. A clean end product after the second cleaning stage means that there are fewer impurities that could interfere with subsequent processing steps such as curing or painting. In this embodiment, post-curing can be carried out in the same device. UV light sources 11 are provided for this purpose. These are activated after the cleaning process is complete and the pressure head 4 has been moved out of the cleaning bath. A special feature of the described embodiments is that all stages of the manufacturing process take place in one device. The products do not need to be removed to be transferred to a subsequent manufacturing step, such as cleaning.Instead, as described above, the resin container is moved to the side to allow free access to the cleaning container. The embodiment shown in Figure 4 proceeds accordingly. A second cleaning container 16 is arranged next to the first cleaning container 6 and can be moved together with it. After the first cleaning stage, the print head 4 moves upwards, then the cleaning containers 6 and 16 move until the second cleaning container 16 is positioned below the print head 4. The print head 4 can then be moved downwards to perform the second cleaning stage. P2024,0436 WO N 3 September 2025 Cleaning system -13 - Reference numeral list 1 Device / 3D printer 2 Product 3.3' Resin container 4 Print head 5.5' Printing unit 6 Cleaning container 7 Control device 8 Separating plate 9 Linear guide 10 Stirring cleaner 11 UV light sources 16 Second cleaning container.

Claims

P2024,0436 WO N 3 September 2025 Cleaning system -14 - Claims 1.Device for the additive manufacturing of products (2), in which a product is produced layer by layer by local curing of a light-curing resin, comprising: - a resin container (3) for receiving a resin during the printing process, - a printhead (4) movable in at least one vertical direction, - a printing unit (5) for locally applying light to the resin held in the resin container (3) to cause local curing of the resin in order to produce the product (2), and - a cleaning container (6) for receiving a cleaning medium, characterized by a control device (7) which is configured to, in a cleaning mode, a) first move the printhead (4) into the cleaning container (6), b) perform a sequence of movements therein by which a flow is generated in the cleaning medium located therein, and c) subsequently move the printhead (4) out of the cleaning medium move. 2.Device according to claim 1, characterized in that the sequence of movements comprises a repeated vertical up / down movement of the print head(4) over a maximum depth of the cleaning container(6), or. P2024,0436 WO N 3 September 2025 Cleaning system -15 -- comprises a repeated horizontal translational movement of the printhead (4) over a maximum of the width of the cleaning container (6), or - comprises a horizontal rotational movement, wherein the sequence of movements may also comprise a combination of the aforementioned movements.

3. Device according to any of the preceding claims, wherein the control device (7) is configured to perform a sequence of movements in the cleaning container (6) comprising a repeated vertical up / down movement of the printhead (4).

4. Device according to any of the preceding claims, wherein the sequence of movements comprises a recurring movement with a period greater than 0.

1.

5. Device according to any of the preceding claims, wherein the sequence of movements comprises a horizontal translational and / or rotational movement of the printhead (4). 6.Device according to any of the preceding claims, wherein the control device (7) is configured to allow a drip-drying phase to follow the removal of the printhead (4) from the cleaning medium and then to repeat steps a) to c).

7. Device according to any of claims 1 to 5, wherein the device has at least one second cleaning container (16), wherein the control device (7) is configured to first move the printhead (4) into the first cleaning container (6) to perform a first cleaning process there and then into the second cleaning container (16). P2024,0436 WO N 3 September 2025 Cleaning system -16 - to move the second cleaning container (16) to perform a second cleaning process there.

8. Device according to claim 7, wherein the first and second cleaning containers (6, 16) are arranged to be displaceable and the control device (7) is configured to displace the second cleaning container (16) into the position of the first cleaning container (6) between the first and second cleaning processes.

9. Device according to any of the preceding claims, wherein a separating plate (8) is provided to which produced products adhere and which is detachably coupled to the pressure head (4). 10.Device according to claim 9, wherein the control device (7) is configured to perform a cleaning of contact surfaces between the pressure head (4) and the separating plate (8) by decoupling the pressure head (4) from the separating plate (8) and moving it in the cleaning medium, wherein the separating plate (8) with the adhering, produced product (2) is coupled back to the pressure head (4) after the cleaning of the contact surfaces and removed from the cleaning container (6).

11. Method for producing a product comprising the steps of: - carrying out an additive process in which the product is built up layer by layer by local curing of a resin, - cleaning the product in a cleaning mode by immersion in a cleaning medium, characterized in that in the cleaning mode. P2024,0436 WO N 3 September 2025 Cleaning system -17 -a) a printhead (4) with which the product (8) is coupled is moved into the cleaning medium,b) a sequence of movements is carried out there in a cleaning phase, by which a flow of the cleaning medium is generated,andc) subsequently the printhead (4) is moved out of the cleaning medium.

12. Method according to claim 11, wherein after cleaning the product (8) a post-curing of the product (8) is carried out.

13. Method according to claim 11 or 12, wherein the sequence of movements comprises: - a repeated vertical up / down movement of the printhead (4) over a maximum of the depth of the cleaning container (6), or - a repeated horizontal translational movement of the printhead (4) over a maximum of the width of the cleaning container (6), or - a horizontal rotational movement, wherein the sequence of movements may also comprise a combination of the aforementioned movements. 14.Method according to any one of claims 11 to 13, wherein in step b) a sequence of movements comprising a repeated vertical up / down movement of the print head (4) is performed.

15. Method according to any one of claims 11 to 14, wherein the sequence of movements comprises a recurring movement with a period greater than 0.

1. P2024,0436 WO N 3 September 2025 Cleaning system -18 - 16. Method according to any one of claims 11 to 15, wherein the sequence of movements comprises a horizontal translational and / or rotary movement of the printhead (4).

17. Method according to any one of claims 11 to 16, wherein after the printhead (4) is moved out of the cleaning medium, a drip-off phase follows, which preferably lasts between 10 s and 120 s, and then steps a) to c) are repeated.

18. Method according to any one of claims 11 to 17, wherein a separating plate (8) is provided to which the product (2) adheres and which can be coupled to and decoupled from the printhead (4).

19. Method according to claim 18, wherein the separating plate (8) is decoupled from the printhead (4) in the cleaning medium and cleaning of contact surfaces between the printhead (4) and the separating plate (8) is carried out by moving the printhead (4) in the cleaning medium. 20.A method according to claim 18 or 19, wherein - after the cleaning phase, the separating plate (8) is decoupled from the printhead (4) and - subsequently, the contact surfaces between the printhead (4) and the separating plate (8) are cleaned by moving the printhead (4) in the cleaning medium.

21. A method according to claim 18 or 19, wherein the cleaning of the product (2) is carried out with the separating plate (8) decoupled and there is no separate cleaning phase. P2024,0436 WO N 3 September 2025 Cleaning system -19 - for cleaning the product (2) with the separating plate (8) coupled.

22. Method according to any one of claims 18 to 21, wherein the separating plate (8) is subsequently coupled back to the printhead (4).

23. Method according to any one of claims 18 to 22, wherein the printhead (4) is first moved into a first cleaning container (6) to perform a first cleaning operation there, and subsequently moved into a second cleaning container (16) to perform a second cleaning operation there, wherein the first and second cleaning containers (6, 16) are arranged to be displaceable and the second cleaning container (16) is moved into the position of the first cleaning container (6) between the first and second cleaning operations.

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