Process arrangement for carrying out a powder-based 3D printing process and method for manufacturing a component in such a process arrangement

Abstract

Process arrangement for carrying out a powder-based 3D printing process, comprising a printing station in which a component (5) can be produced layer by layer in a build chamber (1), and a gripper unit (13) for holding or removing the produced component (5) from the build chamber (1), wherein the gripper unit (13) is a nozzle arrangement with suction nozzles (15) that acts as a holding means which can be coupled to the produced component (5) with suction pressure, wherein the nozzle arrangement has a plurality of suction nozzles (15), characterized in that the suction nozzles (15) are mounted in a nozzle carrier (17) of the nozzle arrangement in a way that allows for vertical adjustment of the stroke independently of one another, and that after the 3D printing process has been carried out, the top surface (23) of the produced component (5) is covered with a powder layer (9), and that before the component is removed, at least the upper powder layer (9) can be automatically extracted by means of the nozzle arrangement.namely, by exposing the upper surface (23) of the component to powder, and that a depowdering station (11) is connected downstream of the printing station, in which coarse and / or fine depowdering takes place, and that the component (5) still located in the powder bed (3) of the build chamber (1) can be grasped fully automatically by means of the nozzle arrangement and can be transferred from the build chamber (1) to the depowdering station (11).

Description

[0001] The invention relates to a process arrangement for carrying out a powder-based 3D printing process according to the preamble of claim 1 and a method for manufacturing a component in such a process arrangement according to claim 10.

[0002] In a typical 3D printing process, a component is manufactured layer by layer. A layer of powder is applied to a build chamber, and then, in a printing process, a binder is applied to the powder layer according to the component's contour. This process is repeated until the component is completed layer by layer.

[0003] In one exemplary process sequence, a curing step can then be performed in which the component, still in the powder bed of the build chamber, is heated to evaporate the binder solvent. For uniform curing, the top surface of the component in the powder bed of the build chamber is coated with a heat-insulating layer of powder. Following curing, the component is removed from the powder bed and transferred to a depowdering station where coarse and fine depowdering of the component can be carried out.

[0004] In an alternative process sequence, curing can be achieved through polymerization processes or similar methods. The invention described below can be used regardless of the specific process sequence chosen.

[0005] The process steps mentioned above, namely component removal, transfer and depowdering, are currently mostly carried out manually and are therefore not suitable for mass production.

[0006] There are currently various approaches to automated depowdering and component removal in the field of 3D printing with powders. For example, DE 10 2012 106141 A1 discloses the use of blowing air from below the build chamber, which fluidizes the powder and causes it to flow away. The loosely placed components in the build chamber sink to the bottom and can then be removed manually. Another solution involves using fluidization while simultaneously tilting the build chamber (US 6 932 935 B1). All of these known solutions have weaknesses in the overall process chain. Therefore, consistently high-quality and economical depowdering cannot be guaranteed.

[0007] The object of the invention is to provide a process arrangement for carrying out a powder-based 3D printing process that is suitable for the mass production of components.

[0008] The problem is solved by the features of claim 1 or claim 10. Preferred embodiments are disclosed in the dependent claims.

[0009] The invention relates to a process arrangement with a printing station in which a component is manufactured layer by layer in a build chamber using a 3D printing process. According to the characterizing part of claim 1, the process arrangement includes a gripper unit for holding the component while it is still in the powder bed of the build chamber or for removing the manufactured component from the build chamber. The gripper unit is preferably a nozzle arrangement with at least one suction nozzle that acts as a holding element. To grip the component in the powder bed of the build chamber, the suction nozzle is coupled to the manufactured component by means of a vacuum. The component can then be transferred from the build chamber by means of the suction nozzle in a removal movement.

[0010] The gripper unit according to the invention can also act as a depowdering agent, as will be described later. In this case, the nozzle arrangement has the additional function of vacuuming away loose powder not bound to components until it can be reused, at which point it encounters a component which is gripped by the vacuum.

[0011] The invention relates generally to a process chain for the (partially) automated depowdering of components with the following process steps: First, a mobile unit containing the powder and components is docked. The docking area for the mobile unit is characterized by a seal against the environment and a defined positioning of the unit relative to the depowdering station, as well as potentially an electrical connection. The defined positioning can be achieved via mechanical stops, as described in the system; positioning using sensors is also possible.

[0012] In the next stage of the process, the covering powder layer is removed. The removal of any powdery coating that may be present on the components can be carried out using a vacuum process, a doctor blade process, or a combination of both. Depending on the subsequent process, removing the top powder layer is not always necessary and can also be done when exposing the components.

[0013] The components are then exposed (possibly layer by layer for multiple component layers): This exposure can be achieved using a nozzle array (hereinafter referred to as the nozzle assembly), which consists of several individual suction nozzles. These suction nozzles can be arranged in a pattern and positioned at the same or different heights. Each nozzle can both draw in powder and hold components. The nozzle array is located vertically above the build platform / powder bed containing the components. The nozzle array and / or the build chamber is designed to be movable in the vertical direction. Before or during the suction process, the nozzles move relative to each other. This causes them to immerse themselves in the powder bed and draw powder from it.The nozzle array can cover the entire surface of the powder bed, or it can be smaller, and the process can be repeated multiple times. Alternatively, several nozzle arrays can operate in parallel or sequentially. The nozzles can be mounted independently of each other, thus replicating the surface of the components within the powder bed. The extracted powder can be reused in a subsequent process, possibly with intermediate reprocessing.

[0014] The components can be manipulated / moved / rotated / picked up using the nozzle array: The components can be gripped and moved by the nozzle array. The soft nozzle heads are brought into contact with the component and held in place by a vacuum. The nozzle heads can conform to the component geometry. The parts can be moved both vertically and horizontally. Rotational movement of the parts is also possible, allowing for defined placement of the parts for subsequent process steps, for example, on a conveyor belt.

[0015] The subsequent coarse depowdering of the components can be carried out as follows: The exposed components can be positioned on a conveyor belt, which can be powder-permeable (e.g., perforated sheet metal). The components are moved relative to a compressed air nozzle or an arrangement of compressed air nozzles (e.g., a ring arrangement). This relative movement guides the components past the compressed air nozzles once or several times, thereby removing any adhering powder. The compressed air can be mixed with an abrasive medium (e.g., powder of the same type as in the powder bed). Furthermore, the components can be rotated between or during the individual processes.

[0016] The fine depowdering of the components can be achieved as follows: To remove any remaining powder, a fine depowdering step is carried out. This can be done using a robot-guided nozzle, ultrasound in a tank, manually, or acoustic cleaning.

[0017] Quality assurance can be performed at the end of the process: This quality control of the components can be carried out using optical measurement or gravimetrically (weighing). The components are then transferred to logistics or subsequent manufacturing processes (for example, sintering).

[0018] The transfer of components can be automatic or manual.

[0019] The process steps can be carried out completely or only partially. In summary, the invention achieves the following advantages, listed in bullet points: an automated sequence of process steps and a chaining of process steps. The following are further details of the invention:

[0020] In a specific technical implementation, after the 3D printing process, the top surface of the manufactured component, which is located in the powder bed, can be covered with a layer of powder. This powder layer acts as thermal insulation for a curing process in which the component is cured at a curing temperature (for example, 140 to 180°C) immediately after 3D printing, allowing the binder solvent to evaporate. It should be emphasized that the invention is not limited to the specific process described above. For example, in an alternative process sequence, curing can be achieved through polymerization processes or similar methods.

[0021] Before removing the component, at least this upper, heat-insulating powder layer can be vacuumed off using the nozzle assembly. This exposes the top surface of the component. The suction nozzle of the nozzle assembly, which acts as a holding element, can therefore dock at least on the top surface of the component.

[0022] In common practice, a depowdering station can be integrated downstream of the 3D printing station. In the depowdering station, coarse and / or fine depowdering of the component takes place. It is preferred that the component, still in the powder bed of the build chamber, can be automatically picked up by the nozzle arrangement and transferred from the build chamber to the depowdering station.

[0023] In a technical implementation, the nozzle arrangement can comprise a multitude of suction nozzles. The nozzle arrangement is positioned above the build chamber. Furthermore, the nozzle arrangement can completely cover the top surface of the powder bed located within the build chamber.

[0024] For reliable component holding, it is preferred that the nozzle arrangement docks onto and holds the component using a plurality of suction nozzles. In this context, it is preferred that the suction nozzles are mounted in a nozzle carrier of the nozzle arrangement so as to be independently adjustable from one another. Preferably, the suction nozzles can be adjustable in a vertical direction. In this case, the suction nozzles can dock in a contour-adapted manner to the geometry of the component's upper surface (each with different stroke lengths).

[0025] To prevent damage to the component when the suction nozzle docks, it is preferred if at least one suction nozzle is elastically mounted in the nozzle assembly. Alternatively and / or additionally, the suction nozzle can have an elastically compliant nozzle head on its side facing the component.

[0026] With regard to a process arrangement suitable for series production, it is preferable if fully automatic depowdering of the component is also possible in the depowdering station. Against this background, the depowdering station can have a tray, particularly one permeable to compressed air, onto which the component can be placed using the gripper unit. A compressed air nozzle arrangement can be provided in the depowdering station, especially for coarse depowdering, by means of which the component is depowdered with compressed air. From a manufacturing perspective, it is advantageous to place the component on a conveyor belt, which allows it to be guided past the compressed air nozzle arrangement. The compressed air nozzle arrangement can encircle the conveyor belt, along with the component placed on it, so that the component can be supplied with compressed air around its entire circumference.

[0027] After coarse depowdering, fine depowdering can be carried out to remove any remaining powder residue from the component. Fine depowdering can preferably be performed using at least one robot-guided compressed air nozzle, ultrasound in an ultrasonic immersion tank, manually, or by acoustic cleaning.

[0028] An embodiment of the invention is described below with reference to the accompanying figures.

[0029] They show: Fig. 1 to Fig. 4 views each, illustrating the removal of a component from a build chamber of a 3D printing station; Fig. 5 a view according to the Fig. 4 according to a second embodiment; Fig. 6 to Fig. 11 detailed views of components of the gripper unit or the depowdering station.

[0030] In the Fig. Figure 1 shows the build chamber 1 of a 3D printing station after a 3D printing process has already been completed. A total of four components 5 are embedded in the powder bed 3 of build chamber 1. Build chamber 1 is bounded by a vertically adjustable lifting platform 7. The lifting platform 7 of build chamber 1 can be adjusted during the 3D printing process and / or during component removal, as described later.

[0031] In the 3D printing process, the components 5 are manufactured layer by layer. A layer of metal powder (alternatively, plastic powder or sand) is applied to the build chamber 1. This metal powder layer is then coated with a binder, corresponding to the component's contour, using a print head (not shown). This process is repeated until the respective component 5 is completed layer by layer. Curing then takes place, during which the components 5, still in the powder bed 3 of the build chamber 1, are heated to a curing temperature to evaporate the binder solvent. To ensure proper curing, the following is required: Fig. 1. The top surface of the two upper components 5 located in the powder bed 3 is coated with a heat-insulating powder layer 9. After curing, the components are removed from the powder bed 3 and transferred to a depowdering station 11. Fig. 8 to Fig. 11).

[0032] A key aspect of the invention relates to a gripper unit 13. This is implemented as a nozzle assembly with a plurality of suction nozzles 15. In the figures, the nozzle assembly is arranged above the build chamber 1 and completely covers the top surface of the powder bed 3 located in the build chamber 1. The suction nozzles 15 are mounted in a nozzle carrier 17 of the nozzle assembly and are vertically adjustable from one another. In addition, each of the suction nozzles 15 is elastically compliant and connected to the nozzle carrier 17 via a spring element 19. Alternatively and / or additionally, the suction nozzles 15 can have an elastically compliant nozzle head 21 on their respective side facing the component 5 ( Fig. 7) exhibit.

[0033] Before the component removal process begins, the nozzle assembly is moved vertically downwards via a stroke until the suction nozzles 15 are immersed in the upper, heat-insulating powder layer 9. The heat-insulating powder layer 9 is then suctioned away by the suction nozzles 15. This occurs while exposing the top surfaces 23 of the two upper components 5 ( Fig. 2 and Fig. 3) As can be seen from the Fig. As shown in Figure 3, the suction nozzles 15 are contour-adapted to the geometry of the respective component top surfaces 23 until they are in contact with them and coupled to the respective component top surface 23 by means of suction pressure. The suction nozzles 15 thus act as holding elements that fix the two exposed components 5 in position within the build chamber 1.

[0034] Subsequently, the two upper components 5, which adhere to the suction nozzles 15 by means of suction pressure, are moved with a reversing stroke R ( Fig. 4) removed from the construction chamber 1 and placed on a compressed air-permeable conveyor belt 25 ( Fig. 8) deposited at depowdering station 11.

[0035] As from the Fig. As can be seen from Figure 5, the suction nozzles 15 are independently adjustable via different stroke distances, so that the suction nozzles 15 can dock in a contour-adapted manner to the geometry of the component top 23.

[0036] In the Fig. Figure 6 shows a detailed view of a suction nozzle 15. Accordingly, the suction nozzle 15 has two channels 14 and 16: a radially outer suction channel 14, which surrounds a central blowing channel 16. Compressed air is blown from the blowing channel 16 to agitate powder and break up more solid powder agglomerates. The agitated powder is then drawn in by the suction channel 14.

[0037] In the depowdering station ( Fig. 8) Coarse depowdering is carried out using a compressed air nozzle arrangement 27, by means of which the respective component 5 is depowdered using compressed air. For this purpose, the component 5, which is placed on the conveyor belt 25, is passed by the compressed air nozzle arrangement 27. In the Fig. 8 The compressed air nozzle assembly 27 encircles the conveyor belt 25, along with the component 5 placed on it, in a ring-like fashion, so that the component 5 can be supplied with compressed air around its entire circumference. The nozzle ring of the compressed air nozzle assembly 27 can blow compressed air containing blasting media (for example, homogeneous powder) onto the component 5. If necessary, the component 5 can be turned / rotated to ensure uniform blasting.

[0038] After the coarse depowdering ( Fig. 8) fine depowdering is carried out, by means of which any remaining powder residues 28 on the component can be removed ( Fig. 9). For this purpose, an actual contour K is used. istThe component 5 is detected by means of an optical sensor device 29 and transmitted to a control unit 31, in which the actual contour K is stored. ist The contour of the component is compared to the desired contour. Based on this comparison, the control unit 31 generates a control signal that moves a robot-assisted compressed air nozzle 33 towards any remaining powder residue and treats it with compressed air.

[0039] Alternatively, fine depowdering can be carried out according to the Fig. 10. Ultrasonic treatment is carried out in an immersion tank 35. For this purpose, the component 5 is transferred by means of the conveyor belt 25 into a carrier basket 37, which is designed as a liquid-permeable wire mesh box and is placed in the immersion tank 35. The ultrasonic treatment takes place in the immersion tank 35, whereby the position of the carrier basket 37, which floats in the immersion tank 35, can be adjusted by means of, for example, air bubbles 39. After the ultrasonic treatment has been carried out, the carrier basket 37, together with the cleaned component 5, is removed from the immersion tank 35.

[0040] Alternatively, fine depowdering can be achieved using acoustic sonic cleaning ( Fig. 11) This takes place. For this purpose, the component 5 located on the conveyor belt 25 is passed through an acoustic cleaning station 41. The sound excites the remaining powder residues 28 to vibrate, causing them to fall off. Reference symbol list 1 Construction Chamber 3 Powder bed 5 components 7 Lifting floor 9 Heat-insulating powder coating 11 Depowdering station 13 gripper units 14 Suction channel 15 suction nozzles 16 blow channel 17 nozzle carriers 19 spring element 21 nozzle head 23 Component top 25 Conveyor belt 27 Compressed air nozzle arrangement 29 Powder residue 29 optical sensor device 31 Control unit 33 Robot-assisted compressed air nozzle 35 ultrasonic immersion tanks 37 Carrier basket 39 air bubbles 41 acoustic cleaning stations QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 102012106141 A1

[0006] US 6932935 B1

[0006]

Claims

[1] Process arrangement for carrying out a powder-based 3D printing process, comprising a printing station in which a component (5) can be produced layer by layer in a build chamber (1), and a gripper unit (13) for holding or removing the produced component (5) from the build chamber (1), characterized by , that the gripper unit (13) is a nozzle arrangement with at least one suction nozzle (15) which acts as a holding means which can be coupled to the manufactured component (5) with a suction pressure, and that in particular the component (5) can be transferred from the build chamber (1) in a removal movement by means of the suction nozzle (15), and / or that in particular the suction nozzle (15) also extracts the powder bed in addition to the holding function. [2] Process arrangement according to claim 1, characterized by, that after the 3D printing process, the top surface (23) of the manufactured component (5) is covered with a powder layer (9), and that before the component is removed, at least the upper powder layer (9) can be extracted by means of the nozzle arrangement, thereby exposing the top surface (23) of the component from powder, and / or that the suction nozzle (15) of the nozzle arrangement, which acts as a holding means, docks at least on the exposed top surface (23) of the component. [3] Process arrangement according to claim 1 or 2, characterized by , that a depowdering station (11) is connected downstream of the printing station, in which coarse and / or fine depowdering takes place, and that in particular the component (5) can be transferred from the build chamber (1) to the depowdering station (11) by means of the nozzle arrangement. [4] Process arrangement according to one of the preceding claims, characterized by, that the nozzle arrangement has a plurality of suction nozzles (15), and / or that the nozzle arrangement is arranged above the build chamber (1) and / or in particular completely covers the top of the powder bed (3) located in the build chamber (1). [5] Process arrangement according to claim 4, characterized by , that the suction nozzles (15), in particular independently of each other, are vertically adjustable in a nozzle carrier (17) of the nozzle arrangement, and / or that the suction nozzles (15) conform to the geometry of the component top surface (23). [6] Process arrangement according to one of the preceding claims, characterized by , that the suction nozzle (15) is elastically compliant in the nozzle assembly, and / or that the suction nozzle (15) has an elastically compliant nozzle head (21) on its side facing the component (5). [7] Process arrangement according to any one of claims 3 to 6, characterized by, that the depowdering station (11) has a storage area (25) which is particularly permeable to compressed air, on which the component (5) can be placed by means of the gripper unit (13), and that the depowdering station (11), in particular for coarse depowdering, has a compressed air nozzle arrangement (27) with which the component (5) is depowdered by means of compressed air. [8] Process arrangement according to claim 7, characterized by , that the storage area (25) is a conveyor belt with which the component (5) placed on it can be guided past the compressed air nozzle arrangement (27), and that in particular the compressed air nozzle arrangement (27) surrounds the conveyor belt (25) together with the component (5) placed on it in a ring shape, so that the component (5) can be supplied with compressed air on its circumference. [9] Process arrangement according to claim 7 or 8, characterized by, that after coarse depowdering a fine depowdering takes place, by means of which powder residues (28) still remaining on the component (5) can be removed, in particular by means of at least one robot-guided compressed air nozzle (33), by means of ultrasound in an immersion tank (35), manually or by means of acoustic cleaning. [10] Method for manufacturing a component in a process arrangement according to one of the preceding claims.

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