DE102020008254B4 - Method and device for separating build-up material from objects produced by 3D printing - Google Patents

Abstract

Method for separating unsolidified building material from at least one object (3, 3') created by layer-by-layer application and selective solidification of the building material as part of a generative construction process by means of a flow of pressurized fluid, wherein a) the at least one object (3, 3') with the building material adhering to it and/or in it is arranged inside a chamber (2, 2') which is sealed pressure-tight, and then b) the interior of the chamber (2, 2') is placed under a second pressure (p2) from a pressure source (6) which is higher than a first pressure (p1) prevailing or generated outside the chamber (2, 2') and in a space (22') or in a pressure sink (5), by flooding the interior of the chamber (2, 2') with pressurized fluid from the pressure source (6) until the second pressure (p2) is present inside the chamber (2, 2'), and then c) a connection is established between the interior of the chamber (2, 2') and the space (22') or with the pressure sink (5) in order to establish at least partial pressure equalization between the first pressure (p1) and the second pressure (p2), whereind) steps a) to c) are carried out in such a way that the flow of pressure fluid resulting from the at least partial pressure equalization between the first pressure (p1) and the second pressure (p2) can grasp the at least one object (3, 3'), and whereine) construction material remaining unsolidified as a result of the flow of pressure fluid is separated from the at least one object (3, 3') and transported along with the flow of pressure fluid, and whereinf) the interior of the chamber (2') is formed between a bell (14') and at least one support or bearing element (23') for the at least one object (3'), wherein the bell (14') and the at least one support or bearing element (23') are formed in such a way and are controlled to be movable relative to one another thatg) for pressure-tight sealing of the interior of the chamber (2'), the bell (14') and the support or bearing element (23') are brought into pressure-tight contact with one another, andh) for establishing the connection between the interior of the chamber (2) and the space (22') or the pressure sink, the bell (14') and the support or bearing element (23') are brought out of contact.

Description

The present invention relates to a method and a device for separating unconsolidated building material from at least one object created by layer-by-layer application and selective consolidation of the building material in the context of a generative construction process, according to claims 1 and 14.

A method for separating unconsolidated construction material from at least one object created by layer-by-layer application and selective consolidation of the construction material in the context of a generative construction process is known from WO 2015/071184 A1 known. There, the object is clamped in a working chamber using a clamping device. An air jet nozzle is provided in the working chamber, which generates an air flow directed at the component, through which any unsolidified build-up material is removed from the object. However, the direction of the air flow must be varied, especially with large objects, in order to cover the entire outer surface of such an object. Furthermore, it is difficult to align the nozzle within the working chamber in such a way that channels formed inside the object and also covered with loose build-up material are covered by the air flow. Last but not least, an operator is required to direct the air flow at the object in a targeted manner, which is a disadvantage in industrially carried out cleaning processes. WO 2020/056355 A1 describes a process for depowdering additively manufactured parts in which the powder is separated from the parts by creating a pressure difference between the powder and the parts. WO 2019 027 404 A1 describes a method for cleaning parts which includes placing the parts in a variable compression chamber, filling the chamber with a liquid, and dissolving pressurized gas in the liquid to form a gas-liquid solution. US 2002/0074022A1 describes a method for cleaning objects in a pressure vessel using a compressed liquid containing a gas that is compressed and expanded one or more times. US 20040072706A1 describes a method for cleaning a surface of an object in which the object is placed on a support area within a pressure chamber and the pressure chamber is then pressurized.

The object of the invention is to provide a method and a device for separating unsolidified building material from at least one object created by layer-by-layer application and selective solidification of the building material within the framework of a generative construction process, which provides a good cleaning result in a simple and efficient manner.

This object is achieved according to the invention by the features of claims 1 and 14.

disclosure of the invention

The production of the at least one three-dimensional object, such as a component or model, which is then separated from the remaining unsolidified building material using the method according to the invention, takes place in a layered construction process with the aid of computer data, in which thin layers of loose powdered building material are repeatedly applied to a construction platform and/or in a construction container and each individual layer is selectively solidified to form a component or model cross-section. Solidification takes place chemically, for example, by using printing technology to selectively apply droplets of adhesive to defined areas of the layers of loose powdered building material. Alternatively, it is possible to selectively fuse or sinter loose powdered building material using high-energy (laser) radiation.

For the purposes of the invention, an object is therefore to be understood as a workpiece or component produced together with the construction platform, or the workpiece or component alone without a construction platform, as well as an object which has been generatively produced in a construction container.

After the additive construction process, powdery building material that has not solidified still adheres to the object. This powdery building material that has not solidified is to be separated from the object by the method according to the invention. Separating the at least one object from loose, non-solidified powdery building material can involve completely unpacking the object from the cake of loose building material or powder or just cleaning off residues of loose powder or building material from the at least one object and optionally also from the construction platform and possibly also from support structures that are still present on the at least one object after unpacking.

The invention therefore relates to a method for separating unconsolidated building material from at least one object created by layer-by-layer application and selective consolidation of the building material in the context of a generative construction process by means of a flow of pressurized fluid.

1. a) das wenigstens eine Objekt mit dem an ihm und/oder in ihm anhaftenden Aufbaumaterial im Inneren einer Kammer angeordnet wird, welche druckdicht verschlossen wird, und dann
2. b) das Innere der Kammer unter einen gegenüber einem außerhalb der Kammer und in einem Raum oder in einer Drucksenke herrschenden oder erzeugten ersten Druck höheren zweiten Druck aus einer Druckquelle gesetzt wird, indem das Innere der Kammer mit Druckfluid aus der Druckquelle insbesondere vollständig geflutet wird, so dass im Inneren der Kammer insbesondere überall der zweite Druck ansteht, und dann
3. c) eine Verbindung zwischen dem Inneren der Kammer mit dem Raum oder mit der Drucksenke hergestellt wird, um einen wenigstens teilweisen Druckausgleich zwischen dem ersten Druck und dem zweiten Druck herzustellen, wobei
4. d) die Schritte a) bis c) derart ausgeführt werden, dass die durch den wenigstens teilweisen Druckausgleich zwischen dem ersten Druck und dem zweiten Druck entstehende Strömung von Druckfluid das wenigstens eine Objekt erfassen kann, und wobei
5. e) infolge der Strömung von Druckfluid unverfestigt verbliebenes Aufbaumaterial von dem wenigstens einen Objekt getrennt und mit der Strömung mittransportiert wird, und wobei
6. f) das Innere der Kammer zwischen einer Glocke und wenigstens einem Stütz- oder Lagerelement für das wenigstens eine Objekt ausgebildet wird, wobei die Glocke und das wenigstens eine Stütz- oder Lagerelement derart ausgebildet und relativ zueinander beweglich gesteuert werden, dass
7. g) zum druckdichten Verschließen des Inneren der Kammer die Glocke und das Stütz- oder Lagerelement in einen druckdichten Kontakt zueinander gebracht werden, und
8. h) zum Herstellen der Verbindung zwischen dem Inneren der Kammer und dem Raum oder der Drucksenke die Glocke und das Stütz- oder Lagerelement außer Kontakt gebracht werden.

The method according to the invention comprises the steps of

1. a) the at least one object with the building material adhering to it and/or in it is arranged inside a chamber which is sealed pressure-tight, and then
2. b) the interior of the chamber is placed under a second pressure from a pressure source which is higher than a first pressure prevailing or generated outside the chamber and in a space or in a pressure sink, by flooding the interior of the chamber with pressurized fluid from the pressure source, in particular completely, so that the second pressure is present everywhere inside the chamber, and then
3. c) a connection is established between the interior of the chamber and the space or with the pressure sink in order to establish at least partial pressure equalization between the first pressure and the second pressure, wherein
4. d) steps a) to c) are carried out in such a way that the flow of pressure fluid resulting from the at least partial pressure equalization between the first pressure and the second pressure can detect the at least one object, and wherein
5. e) as a result of the flow of pressure fluid, any construction material remaining unsolidified is separated from the at least one object and transported along with the flow, and wherein
6. f) the interior of the chamber is formed between a bell and at least one support or bearing element for the at least one object, wherein the bell and the at least one support or bearing element are designed and controlled to be movable relative to one another in such a way that
7. g) for the pressure-tight closure of the interior of the chamber, the bell and the support or bearing element are brought into pressure-tight contact with each other, and
8. (h) to establish communication between the interior of the chamber and the space or pressure sink, the bell and the support or bearing element are brought out of contact.

In step g), the chamber is then separated from the space or pressure sink so that no pressure equalization can take place, while in step h), pressure equalization can take place. Since a bell opening of a bell can provide a relatively large opening cross-section, pressure equalization advantageously takes place quickly or abruptly.

The bell can be any bell-shaped, box-shaped or cup-shaped structure enclosing an interior space.

It is particularly preferred that the connection between the interior of the chamber and the space or the pressure sink is made suddenly or abruptly. This is achieved in the method by moving the bell from the lowered position to a raised position. Since such a bell, which encloses the at least one object in the lowered position, provides a relatively large flow cross-section through its bell opening in the raised position, the pressure equalization can take place very quickly.

In addition, a vent valve with a flow cross-section can be provided, which is then moved from its closed position to its open position to equalize the pressure.

The support or bearing element can be any element or any structural unit on or at which the at least one object can be stored or transported, in particular on a flat surface. In this respect, a surface of the support or bearing element facing the at least one object is preferably flat so that this flat surface can form a pressure-tight connection with the peripheral edge of the bell, which surrounds the bell opening, in the event of contact. The bell, which interacts with the support or bearing element, which is preferably designed as a flat surface, then forms a plate valve as a vent valve and second valve, with the bell edge then representing a valve sealing surface of the plate valve.

In contrast to the prior art mentioned at the beginning, a directed air jet is not generated by means of a nozzle, but rather a flow of pressurized fluid through a pressure equalization between the second, higher pressure in the chamber and the first, lower pressure in the pressure sink or in the space. The chamber space is in particular completely flooded with the pressurized fluid under the second pressure until the second pressure acts or is present everywhere in the chamber before the pressure equalization is established. In contrast, in the case of a compressed air jet flowing from a nozzle and directed at the object according to the prior art mentioned at the beginning, the higher pressure only acts in the local area of the compressed air jet, while zones of the working chamber that deviate from this have a lower pressure.

A sufficient flow velocity of the flow of pressure fluid is created in particular This is especially the case when the pressure equalization takes place explosively, abruptly or suddenly, which can be achieved, for example, by a large flow cross-section and/or a high opening speed of a valve, for example in the form of a bell that interacts with a particularly flat valve sealing surface, through which the pressure equalization is achieved. The pressure equalization, which then takes place in particular explosively, therefore generates a strong flow of pressurized fluid, in which any building material that has not solidified is detached from the at least one object and "carried along".

The invention therefore has the advantage that it provides a good cleaning result of the at least one object with little effort, because then a pressure fluid jet that has to be directed multiple times towards the object can be dispensed with.

The subclaims contain embodiments of the method which further develop the invention.

Preferably, any build-up material that remains unsolidified and is transported along with the flow is separated from the flow and collected in a filter device. For this purpose, the flow is passed through the filter device.

The interior of the chamber can also be connected to the pressure source via at least one first opening in a chamber wall of the chamber, wherein the interior of the chamber is placed under the second pressure of the pressure source by a coordinated control of at least one first valve arranged in the first opening.

Therefore, according to a development of the method, the first connection can additionally comprise a first valve that can be controlled in a coordinated manner by a controller. Furthermore, the second connection can additionally comprise a second valve that can be controlled in a coordinated manner by the controller.

The pressure source can, for example, comprise a pressure fluid supply such as a compressed air supply and/or a compressor and/or a pressure fluid pump. The space can be any space in which the lower first pressure is present or prevails. This first pressure can be generated in particular by evacuating the space and then represents the pressure in a vacuum. The pressure sink can also represent a vacuum. The space and/or the pressure sink can therefore also be realized in a container that has been evacuated.

In particular, the support or bearing element can comprise a construction platform of the at least one object. In some objects, the at least one object is manufactured in one piece with the construction platform using a 3D printing process. Consequently, the construction platform then has an advantageous dual function in that, on the one hand, it represents the "construction plate" when producing the at least one object during the construction process and, on the other hand, with its upward-facing surface, it represents the sealing surface of the support or bearing element that interacts with the bell edge of the bell.

The bell can also comprise a construction container in which the at least one object has been additively constructed and whose upper construction container opening, which is open after the construction process, is firmly closed by a lid, with the at least one object remaining in the construction container. The chamber is then formed by the interior of the construction container, which is firmly closed by the lid and which is closed off at the top by the lid and at the bottom by the construction platform. The construction container then forms a pressure-tight seal against the construction platform with its construction container edge, which surrounds the lower construction container opening in the vertical direction. To equalize the pressure, the construction container, which stands on the construction platform, for example, but has no fixed connection to it, is lifted off the construction platform together with the lid, particularly abruptly or suddenly.

The bell can also be formed by a lid which, after the construction process, is placed on the upper construction container opening of the construction container in a way that seals against the upper construction container edge, with at least one object being left in the construction container. To equalize the pressure, the lid is then lifted off the upper construction container edge, particularly abruptly or suddenly, which creates pressure equalization. In this case, the construction container together with the construction platform is used as a support or bearing element.

The support or bearing element can also comprise a conveyor belt of a conveying direction on which the at least one object is conveyed. The bell can then be controlled in a coordinated manner between a position lowered onto the conveyor belt, in which an edge of the bell makes sealing contact with the conveyor belt, and a position raised from the conveyor belt, in which the edge of the bell is out of contact with the conveyor belt.

1. a) die Glocke eine Kammerwandung der Kammer ausbilden und der Raum oder die Drucksenke außerhalb der Glocke ausgebildet und in der auf das Förderband abgesenkten Stellung der Glocke durch die Glocke, ein Gehäuse und das Förderband begrenzt sein, wobei die Glocke an dem Gehäuse relativ zu dem Förderband beweglich geführt ist, sowie
2. b) das wenigstens eine Objekt durch einen Transport mittels des Förderbands durch eine verschließbare Zuführöffnung des Gehäuses hindurch in das Innere des Gehäuses und durch eine verschließbare Abführöffnung des Gehäuses hindurch aus dem Inneren des Gehäuses transportierbar sein, wobei bei dem Verfahren
   • α) in der vom Förderband abgehobenen Stellung der Glocke das wenigstens eine Objekt durch den Transport mittels des Förderbands durch die geöffnete Zuführöffnung des Gehäuses hindurch in das Innere des Gehäuses transportiert, und dann
   • β) die Glocke in die auf das Förderband abgesenkte Stellung gebracht sowie die Zuführöffnung und die Abführöffnung des Gehäuses verschlossen werden, und dann
   • γ) das Innere der Kammer unter den zweiten Druck aus der Druckquelle gesetzt wird, indem das Innere der Kammer mit Druckfluid aus der Druckquelle vollständig geflutet wird, und dann
   • σ) die Glocke insbesondere abrupt oder schlagartig in die vom Förderband abgehobene Stellung gebracht wird, wodurch das Innere der Kammer mit dem Inneren des Raums oder der Drucksenke verbunden wird und infolge des Druckausgleichs zwischen dem zweiten Druck in der Kammer und dem ersten Druck in dem Raum oder der Drucksenke die das wenigstens eine Objekt erfassende Strömung von Druckfluid erzeugt wird, und dann
   • ε) die Abführöffnung des Gehäuses geöffnet wird, und dann
   • ζ) das wenigstens eine Objekt durch den Transport mittels des Förderbands in Förderrichtung durch die geöffnete Abführöffnung hindurch aus dem Inneren des Gehäuses transportiert wird.

This can

1. a) the bell forms a chamber wall of the chamber and the space or pressure sink is formed outside the bell and in the position of the bell lowered onto the conveyor belt is limited by the bell, a housing and the conveyor belt, the bell being guided on the housing so as to be movable relative to the conveyor belt, and
2. b) the at least one object can be transported by means of the conveyor belt through a closable feed opening of the housing into the interior of the housing and through a closable discharge opening of the housing out of the interior of the housing, wherein in the method
   • α) in the position of the bell lifted off the conveyor belt, the at least one object is transported by means of the conveyor belt through the opened feed opening of the housing into the interior of the housing, and then
   • β) the bell is brought into the position lowered onto the conveyor belt and the feed opening and the discharge opening of the housing are closed, and then
   • γ) the interior of the chamber is placed under the second pressure from the pressure source by completely flooding the interior of the chamber with pressure fluid from the pressure source, and then
   • σ) the bell is brought into the position lifted off the conveyor belt, in particular abruptly or suddenly, whereby the interior of the chamber is connected to the interior of the space or the pressure sink and, as a result of the pressure equalization between the second pressure in the chamber and the first pressure in the space or the pressure sink, the flow of pressure fluid capturing the at least one object is generated, and then
   • ε) the discharge opening of the housing is opened, and then
   • ζ) the at least one object is transported out of the interior of the housing by means of the conveyor belt in the conveying direction through the opened discharge opening.

Preferably, the conveyor belt is stopped when carrying out the above steps β), γ) and σ).

Between the above steps δ) and ε), unconsolidated build-up material separated from the at least one object as a result of the flow and transported along with the flow can also be removed from the space or the pressure sink. This can be achieved, for example, by collecting the unconsolidated build-up material in a collecting container.

The above-described embodiment of the method is particularly suitable for industrial application when it is successively applied to several objects transported one after the other in the conveying direction by the conveyor belt.

Compressed air and/or a protective gas can be used as the pressure fluid.

It is particularly preferred that the flow of pressurized fluid in the vertical direction is generated and directed from a higher level than a lower level in the direction of the lower level. The effect of gravity then supports the loosening and removal of unsolidified building material from the at least one object.

1. a) eine druckdicht setzbare Kammer, welche ausgebildet ist zur Anordnung des wenigstens einen Objekt in deren Innerem,
2. b) einen Raum oder eine Drucksenke, welcher oder welche unter dem ersten Druck steht oder welcher unter den ersten Druck gesetzt wird,
3. c) eine Druckquelle, welche unter dem zweiten Druck steht oder welche unter den zweiten Druck gesetzt wird,
4. d) eine Steuerung,
5. e) wenigstens eine erste Verbindung zwischen dem Inneren der Kammer und der Druckquelle, welche durch die Steuerung hergestellt oder gesperrt werden kann,
6. f) wenigstens eine zweite Verbindung zwischen dem Inneren der Kammer und dem Raum oder der Drucksenke, welche durch die Steuerung hergestellt oder gesperrt werden kann, wobei
7. g) das Innere der Kammer zwischen einer Glocke und wenigstens einem Stütz- oder Lagerelement für das wenigstens eine Objekt ausgebildet ist, wobei die Glocke und das wenigstens eine Stütz- oder Lagerelement derart ausgebildet und durch die Steuerung relativ zueinander beweglich und koordiniert gesteuert sind, dass
8. h) zum druckdichten Verschließen des Inneren der Kammer die Glocke und das Stütz- oder Lagerelement in einen druckdichten Kontakt zueinander gebracht werden, und
9. i) zum wenigstens teilweisen Herstellen der zweiten Verbindung zwischen dem Inneren der Kammer und dem Raum oder der Drucksenke die Glocke und das Stütz- oder Lagerelement außer Kontakt gebracht werden.

The invention also relates to a device for separating unconsolidated building material from at least one object created by layer-by-layer application and selective consolidation of the building material in the context of a generative construction process, which device comprises at least the following:

1. a) a pressure-tight chamber which is designed to accommodate the at least one object in its interior,
2. b) a space or pressure sink which is under the first pressure or which is placed under the first pressure,
3. c) a pressure source which is under the second pressure or which is placed under the second pressure,
4. d) a control system,
5. e) at least one first connection between the interior of the chamber and the pressure source, which can be established or blocked by the control,
6. f) at least one second connection between the interior of the chamber and the space or pressure sink, which can be established or blocked by the control, wherein
7. g) the interior of the chamber is formed between a bell and at least one support or bearing element for the at least one object, wherein the bell and the at least one support or bearing element are formed and controlled by the control system to be movable relative to one another and in a coordinated manner such that
8. h) for pressure-tight sealing of the interior of the chamber, the bell and the support or Bearing element are brought into pressure-tight contact with each other, and
9. i) to at least partially establish the second connection between the interior of the chamber and the space or pressure sink, the bell and the support or bearing element are brought out of contact.

According to a development of the device, the first connection can additionally comprise a first valve that can be controlled in a coordinated manner by the controller. Furthermore, the second connection can comprise a second valve that can be controlled in a coordinated manner by the controller.

In particular, the support or bearing element can comprise a conveyor belt of a conveying direction on which the at least one object can be conveyed.

Furthermore, the bell can be controlled in a coordinated manner between a position lowered onto the support or bearing element, in particular onto the conveyor belt, in which an edge of the bell makes sealing contact with the support or bearing element, in particular the conveyor belt, and a position raised from the support or bearing element, in particular from the conveyor belt, in which the edge of the bell is out of contact with the support or bearing element, in particular with the conveyor belt.

The lowered position and the raised position and also intermediate positions of the bell in relation to the support or bearing element can be brought about in particular by a coordinated controllable lifting device which is operatively connected to the bell and positions the bell in particular in the vertical direction.

1. a) die Glocke eine Kammerwandung der Kammer ausbilden und der Raum oder die Drucksenke außerhalb der Glocke ausgebildet sein und in der auf das Förderband abgesenkten Stellung der Glocke durch die Glocke, ein Gehäuse und das Förderband begrenzt sein, wobei die Glocke an dem Gehäuse relativ zu dem Förderband beweglich geführt ist, wobei
2. b) das wenigstens eine Objekt durch einen Transport mittels des Förderbands durch eine verschließbare Zuführöffnung des Gehäuses hindurch in das Innere des Gehäuses und durch eine verschließbare Abführöffnung des Gehäuses hindurch aus dem Inneren des Gehäuses transportierbar ist.

Also

1. a) the bell forms a chamber wall of the chamber and the space or the pressure sink is formed outside the bell and is limited in the position of the bell lowered onto the conveyor belt by the bell, a housing and the conveyor belt, wherein the bell is guided on the housing so as to be movable relative to the conveyor belt, wherein
2. b) the at least one object can be transported by means of the conveyor belt through a closable feed opening of the housing into the interior of the housing and through a closable discharge opening of the housing out of the interior of the housing.

Advantageous developments of the invention arise from the patent claims, the description and the drawings. The advantages of features and combinations of several features mentioned in the introduction to the description are merely examples and can be used alternatively or cumulatively without the advantages necessarily having to be achieved by embodiments according to the invention. Further features can be found in the drawings - in particular the geometries shown and the relative dimensions of several components to one another as well as their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different patent claims is also possible in deviation from the selected relationships of the patent claims and is hereby suggested. This also applies to features that are shown in separate drawings or mentioned in their description. These features can also be combined with features of different patent claims. Features listed in the patent claims can also be omitted for other embodiments of the invention.

drawing

• 1 eine schematische perspektivische Querschnittdarstellung einer Vorrichtung zum Trennen von realen, additiv hergestellten Objekten von unverfestigt verbliebenem Aufbaumaterial;
• 2 eine schematische perspektivische Querschnittdarstellung einer bevorzugten Ausführungsform einer Vorrichtung zum Trennen von realen, additiv hergestellten Objekten von unverfestigt verbliebenem Aufbaumaterial gemäß der Erfindung, mit welcher eine bevorzugte Ausführungsform des erfindungsgemäßen Verfahrens ausgeführt wird;
• 2A-2C die Vorrichtung von 2 in verschiedenen Zuständen, welche Schritte des Verfahrens entsprechen.

An embodiment of the invention is shown in the drawing below and explained in more detail in the following description. In the drawing,

• 1 a schematic perspective cross-sectional view of a device for separating real, additively manufactured objects from unsolidified remaining building material;
• 2 a schematic perspective cross-sectional view of a preferred embodiment of a device for separating real, additively manufactured objects from unsolidified building material according to the invention, with which a preferred embodiment of the method according to the invention is carried out;
• 2A-2C the device of 2 in different states, which correspond to steps of the procedure.

Description of the embodiment

1 shows a schematic perspective view of a part of a device 1 for separating additively manufactured 3D objects from unsolidified remaining building material from unsolidified remaining (loose) building material.

The device 1 comprises a pressure-tight chamber 2, which is designed for example for clamping an object 3 in a clamping device 4, whereby any (loose) material remaining unconsolidated on the object 3 building material adheres. The chamber 2 can have, for example, a pressure-tight, sealable door (not shown here) for the supply and removal of the object 3. The device also comprises a pressure sink 5, which is under the first pressure p ₁ and is formed, for example, by an evacuated container, and a pressure source 6, which is under the second pressure p ₂ and is formed here, for example, by a compressed air reservoir, which is filled with compressed air by a compressor, for example, whereby a pressure control ensures, for example, that the second pressure p ₂ in the compressed air reservoir remains within certain tolerance limits. The chamber 2 is formed here, for example, by a cleaning chamber, which is surrounded by a housing wall of a housing 7 and which can be connected to the pressure source 6 by means of a first opening 8, which is formed, for example, in the position of use of the device 1 and viewed in the vertical direction in a ceiling of the housing wall. In the area of the first opening 8, a first valve 9 is arranged, with which the first opening 8 can be opened or closed. The upper arrow in 1 symbolizes the compressed air flow when the first valve 9 is opened. For example, before the first valve 9 is opened, the chamber 2 is under atmospheric pressure, which is lower than the second pressure p ₂ .

In addition, the housing 7 also comprises a second opening 10, here preferably in a bottom of the housing wall, in which a second valve 11 is arranged, with which a second connection between the interior of the chamber 2 and the pressure sink 5 connected to the second opening 10 can be opened or blocked. The middle arrow in 1 symbolizes the compressed air flow when the second valve 11 is opened. Between the second opening 10 or the second valve 11 and the pressure sink 5, a filter device 12 is preferably arranged, through which loose building material, which the compressed air originating from the pressure source 6 has separated as a compressed air flow from the object 3 in the chamber 2 and then carries with it, is separated from the compressed air flow, so that essentially purified compressed air is discharged into the pressure sink 5, as the lower arrow in 1 symbolized.

Instead of an evacuated container, the pressure sink 5 can also be embodied in any space, for example by the atmosphere or environment, if only the first pressure p ₁ prevailing there is lower than the second pressure p ₂ .

The pressure source 6 or its pressure generator, for example in the form of a compressor, the first valve 9, the second valve 11, for example designed as solenoid valves, and the pressure sink 5 or its vacuum generator are controlled in a coordinated manner, for example by a higher-level electronic control system, in order to carry out the process.

• Zunächst wird das Objekt 3 beispielsweise zusammen mit der einstückig an ihm angeformten Bauplattform 13 sowie mit dem an ihm und/oder in ihm anhaftenden losen Aufbaumaterial im Inneren der Kammer 2 angeordnet und beispielsweise in der Spanneinrichtung 4 gespannt. Dann wird die Kammer 2 druckdicht verschlossen. Die Kammer 2 steht dann beispielsweise unter Atmosphärendruck. Das erste Ventil 9 wie auch das zweite Ventil 11 sind zunächst geschlossen.

Regarding the device of 1 The procedure then runs in at least the following steps:

• First, the object 3 is arranged inside the chamber 2, for example together with the construction platform 13 formed integrally on it and with the loose construction material adhering to it and/or in it, and is clamped, for example, in the clamping device 4. The chamber 2 is then sealed pressure-tight. The chamber 2 is then under atmospheric pressure, for example. The first valve 9 and the second valve 11 are initially closed.

The interior of the chamber 2 is then completely placed under the second pressure p ₂ of the pressure source 6, which is in particular significantly higher than the atmospheric pressure, by opening the first valve 9 until the second pressure p ₂ is present everywhere inside the chamber 2. A pressure sensor (not shown here) arranged in the chamber 2, which reports the respective actual pressure p _ist in the chamber 2 to a higher-level electronic control, can be used to check when the actual pressure p _ist in the chamber 2 has reached the second pressure p _2. In this respect, a pressure control is preferably implemented here, which regulates the actual pressure p _ist in the chamber 2 to the second pressure as the target pressure p _soll .

When the actual pressure p _has reached the second pressure p ₂ , the first valve 9 is preferably closed and the second valve 11 is opened, in particular abruptly or suddenly. This leads to an immediate pressure equalization between the relatively high second pressure p ₂ prevailing in the chamber 2 and the significantly lower first pressure p ₁ in the pressure sink 5. The low first pressure p ₁ in the pressure sink 5 can also be maintained, for example, by a pressure control. The pressure equalization creates a compressed air flow which captures the object 3 and separates or cleans loose building material from the object 3. At the same time, the compressed air flow transports this loose building material with it and into the filter device 12, in which the building material is then separated from the compressed air flow, so that finally cleaned compressed air reaches the pressure sink 5. The building material separated from the object 3 can then be led from the filter device 12 into a collecting container and then used, for example, for the construction of another object.

After cleaning, object 3 can then be removed from chamber 2.

2 shows a schematic perspective view of a part of a preferred embodiment of a device 1' for separating additively manufactured 3D objects from unsolidified remaining building material from unsolidified remaining (loose) building material according to the invention.

As with the embodiment of 1 There is also a chamber 2' here, which is chambered by a bell 14' with a bell opening 15'. The bell opening 15' is bordered by a circumferential bell edge 16', which is arranged, for example, in one plane. A circumferential seal (not shown here) can be arranged on the circumferential bell edge 15'.

The bell 14' is guided on a housing 7' for example so that it can move vertically and can be moved vertically between a raised position and a lowered position by a lifting device 17', which is also mounted on the housing 7'. A feed bulkhead 18' and a discharge bulkhead 19' are also mounted so that they can move vertically relative to the housing 7', with the feed bulkhead 18' exposing a feed opening 20' of the housing 7' in an open position and closing the feed opening 20' in a closed position. Similarly, the discharge bulkhead 19' exposing a discharge opening 21' of the housing 7' in an open position and closing it in a closed position.

The bell 14' forms a chamber wall of the chamber 2' and a pressure sink 5' is formed in a space 22' which is formed outside the bell 14' and is delimited by an outer surface of the bell 14', an inner surface of the housing 7' and the conveyor belt 23' when the bell 14' is lowered onto a conveyor belt 23' of a conveyor device 24'. The higher second pressure p ₂ is generated in the chamber 2' for example by the interior of the bell 14' in its position lowered onto the conveyor belt 23' being pressurized by a first valve (not shown here) as in the embodiment of 1 by pressure from a pressure source not shown here. Likewise, the lower first pressure p ₁ in the space 22' can be generated by connecting the space 22' in an analogous manner to a pressure sink via a second valve.

In the lowered position, the bell edge 16' or the seal arranged on it as well as a lower edge of the feed bulkhead 18' and the discharge bulkhead 19' contact the conveyor belt 23' of the conveyor device 24', which also forms a component of the second embodiment of the device 1'. In this respect, in the lowered position, the bell edge 16' or the seal arranged on it as well as a lower edge of the feed bulkhead 18' and the discharge bulkhead 19' lie in the plane of the conveyor belt 23' and seal against it, for example in a pressure-tight manner. As can be seen from 2 As can easily be imagined, in the position of the bell 14' raised from the conveyor belt 23', a pressure equalization takes place between the higher second pressure p ₂ in the chamber 2 and the lower pressure in the space 22', whereby a compressed air flow is created which is directed out of the chamber 2' into the space 22' and by means of which loose building material is released from the object 3 arranged on the conveyor belt 23' and is transported away by it. To collect the loose building material transported by the compressed air flow, a collecting container 25' is arranged below the conveyor belt.

The conveyor belt 23' is designed to transport additively produced objects in a conveying direction which is 2A symbolized by the arrow.

The conveyor device 24' or a drive of the conveyor belt 23', the lifting device 17', the feed bulkhead 18' and the discharge bulkhead 19' or their drives as well as the first valve and the second valve, for example designed as solenoid valves, are controlled in a coordinated manner by a higher-level electronic control system in order to carry out the process.

• Zunächst werden bevorzugt mehrere Objekte 3' auf dem Förderband in Reihe hintereinander positioniert, wobei die Objekte 3' beispielsweise wiederum mit ihren Bauplattformen 13' verbunden sind. Dabei befindet sich die Glocke 14' in der abgehobenen Stellung und das Zuführschott 18' und das Abführschott 19' jeweils in der Öffnungsstellung. Das Abführschott 19' kann sich aber auch noch in der Schließstellung befinden. Das erste Ventil und das zweite Ventil sind beispielsweise geschlossen.

With regard to the second embodiment of the device 1' of 2 The procedure then runs in at least the following steps:

• First, several objects 3' are preferably positioned one behind the other on the conveyor belt, with the objects 3' being connected, for example, to their construction platforms 13'. The bell 14' is in the raised position and the feed bulkhead 18' and the discharge bulkhead 19' are each in the open position. The discharge bulkhead 19' can also be in the closed position. The first valve and the second valve are closed, for example.

At the same time, thereafter or before, according to 2A the conveyor belt 23' is started and conveys a first object 3' over the opened feed gate 18' into the housing 7' until it is located below the bell 14'. Then the drive of the conveyor belt 23' is switched off so that the position of the first object 3' in relation to the bell 14' remains Then the bell 14' is moved to the lowered position, the feed bulkhead 18' and the discharge bulkhead 19', if the latter is not already in the closed position, are each moved to the closed position by the control system. This situation is in 2B shown.

Then, the now pressure-tight chamber 2', which has now formed between the bell 14' and the conveyor belt 23', is flooded with compressed air from the compressed air source by opening the first valve until the entire interior of the chamber 2' is under the higher second pressure p ₂ , which can be determined, for example, by a pressure sensor. Then the first valve is closed. At the same time, after this or before, the space 22', which has now formed pressure-tight between the outer surface of the bell 14', the conveyor belt 23' and the inner surface of the housing 7', is connected to the pressure sink by opening the second valve and in particular evacuated, so that a relatively large pressure gradient is created between the chamber 2' and the space 22'. The second valve, which is arranged, for example, in an opening in the wall of the housing 7', is then closed.

Then the lifting device 17' is controlled by the control system so that the bell 14' is abruptly lifted off the conveyor belt 23', which in 2C is shown. This results in a pressure equalization between the higher second pressure p ₂ in the chamber 2' and the lower first pressure p ₁ in the space 22', whereby a compressed air flow is created from the chamber 2' into the space 22', which detaches loose building material from the first object 3' and transports or entrains it. Due to gravity, the loose building material then passes the conveyor belt 23', for example laterally, in order to reach the collecting container 25', in which it is collected.

Then the feed gate 18' and the discharge gate 19' are controlled into the open position and the conveyor belt 23' is started again so that the cleaned first object 3' moves out of the housing 7' and a second object 3' arranged in series behind the first object 3' on the conveyor belt 23' moves into the housing 7' in order to apply the method again to the second object 3'. It is obvious that the method can be applied successively to a plurality or a plurality of objects 3' arranged on the conveyor belt 23'.

reference number list

1, 1'

device

2, 2'

chamber

3, 3'

object

4

clamping device

5

pressure sink

6

pressure source

7, 7'

Housing

8

first opening

9

first valve

10

second opening

11

second valve

12

filter device

13, 13'

construction platform

14'

bell

15'

bell opening

16'

bell rim

17'

lifting device

18'

feed bulkhead

19'

discharge bulkhead

20'

feed opening

21'

discharge opening

22'

Space

23'

conveyor belt

24'

conveyor system

25'

collection container

Claims (18)

Method for separating unconsolidated building material from at least one object (3, 3') created by layer-by-layer application and selective consolidation of the building material as part of a generative construction process by means of a flow of pressurized fluid, wherein a) the at least one object (3, 3') with the building material adhering to it and/or in it is arranged inside a chamber (2, 2') which is sealed pressure-tight, and then b) the interior of the chamber (2, 2') is placed under a second pressure (p 2 ) from a pressure source (6) which is higher than a first pressure (p ₁ ) prevailing or generated outside the chamber (2, 2') and in a space ( ₂₂ ') or in a pressure sink (5), by flooding the interior of the chamber (2, 2') with pressurized fluid from the pressure source (6) until the second pressure (p ₂ ) is reached inside the chamber (2, 2'). is present, and then c) a connection is established between the interior of the chamber (2, 2') with the space (22') or with the pressure sink (5) in order to establish at least partial pressure equalization between the first pressure (p ₁ ) and the second pressure (p ₂ ), wherein d) steps a) to c) are carried out in such a way that the pressure created by the at least partial pressure equalization a flow of pressure fluid which is formed between the first pressure (p ₁ ) and the second pressure (p ₂ ) can capture the at least one object (3, 3'), and wherein e) as a result of the flow of pressure fluid, any construction material which has not solidified is separated from the at least one object (3, 3') and transported along with the flow of pressure fluid, and wherein f) the interior of the chamber (2') is formed between a bell (14') and at least one support or bearing element (23') for the at least one object (3'), wherein the bell (14') and the at least one support or bearing element (23') are formed and controlled to be movable relative to one another in such a way that g) for pressure-tight sealing of the interior of the chamber (2'), the bell (14') and the support or bearing element (23') are brought into pressure-tight contact with one another, and h) for establishing the connection between the interior of the chamber (2) and the space (22') or the Pressure sink the bell (14') and the support or bearing element (23') are brought out of contact. procedure according to claim 1 , characterized in that unsolidified build-up material transported along with the flow of pressure fluid is separated from the flow and collected in a filter device (12). procedure according to claim 1 or 2 , characterized in that the connection between the interior of the chamber (2, 2') and the space (22') or the pressure sink (5) is established suddenly or abruptly. Method according to one of the preceding claims, characterized in that the support or bearing element (23') comprises a conveyor belt of a conveying direction on which the at least one object (3') is conveyed, and that the bell (14') is controlled in a coordinated manner between a position lowered onto the conveyor belt, in which a bell edge (16') of the bell (14') makes sealing contact with the conveyor belt, and a position raised from the conveyor belt, in which the bell edge (16') of the bell (14') is out of contact with the conveyor belt. procedure according to claim 4 , characterized in that a) the bell (14') forms a chamber wall of the chamber (2') and the space (22') or the pressure sink is or will be formed outside the bell (14') and, in the position of the bell (14') lowered onto the conveyor belt, is delimited by the bell (14'), a housing (7') and the conveyor belt, wherein the bell (14') is movably guided on the housing (7') relative to the conveyor belt, and that b) the at least one object (3') can be transported by means of the conveyor belt through a closable feed opening (20') of the housing (7') into the interior of the housing (7') and through a closable discharge opening (21') of the housing (7') out of the interior of the housing (7'), wherein in the method α) in the position of the bell (14') raised from the conveyor belt, first the at least one object (3') is the transport by means of the conveyor belt through the opened feed opening (20') of the housing (7') into the interior of the housing (7') into a position below the bell (14'), and then β) the bell (14') is brought into the position lowered onto the conveyor belt and the feed opening (20') and the discharge opening (21') of the housing are closed or the feed opening (20') is closed and the discharge opening (21') is kept closed, and then γ) the interior of the chamber (2') is placed under the second pressure (p ₂ ) by flooding the interior of the chamber (2') with pressurized fluid from the pressure source (6), and then δ) the bell (14') is brought, in particular abruptly or suddenly, into the position raised from the conveyor belt, whereby the interior of the chamber (2') is connected to the interior of the space (22') or the pressure sink and as a result of the pressure equalization between the second pressure (p ₂ ) in the chamber (2') and the first pressure (p ₁ ) in the space (22') or the pressure sink, the flow of pressurized fluid detecting the at least one object (3') is generated, and then ε) the discharge opening (21') of the housing (7') is opened, and then ζ) the at least one object (3') is transported out of the interior of the housing (7') by means of the conveyor belt through the opened discharge opening (21'). procedure according to claim 5 , characterized in that the conveyor belt is stopped during the execution of steps β), γ) and σ). procedure according to claim 5 or 6 , characterized in that between steps δ) and ε), unsolidified building material separated from the at least one object (3') as a result of the flow and transported together with the flow is removed from the space (22'). Method according to one of the Claims 5 until 7 , characterized in that it is successively applied to several objects (3') transported one after the other by the conveyor belt in the conveying direction. Method according to one of the preceding claims, characterized in that a construction platform (13') is used as the support or bearing element, on which the at least one object (3') has been additively produced. Method according to one of the preceding claims, characterized in that a construction container is used as the bell (14'), in which the at least one object (3') has been additively produced. Method according to one of the preceding claims, characterized in that compressed air and/or a protective gas is used as the pressure fluid. Method according to one of the preceding claims, characterized in that the first pressure (p ₁ ) is generated by evacuating the space (22') or the pressure sink. Method according to one of the preceding claims, characterized in that the flow of pressurized fluid, viewed in the vertical direction, is generated and directed from a higher level than a lower level in the direction of the lower level. Device for separating unsolidified building material from at least one object (3, 3') created by layer-by-layer application and selective solidification of the building material as part of a generative construction process by means of a flow of pressurized fluid, comprising at least the following: a) a pressure-tight chamber (2, 2') which is designed to arrange the at least one object (3, 3') in its interior, b) a space (22') or a pressure sink (5) which is under the first pressure (p ₁ ) or which is set under the first pressure (p ₁ ), c) a pressure source (6) which is under the second pressure (p ₂ ) or which is set under the second pressure (p ₂ ), d) a control, e) at least one first connection (8) between the interior of the chamber (2, 2') and the pressure source (6), which can be established or blocked by the control, f) at least one second connection (10, 16') between the interior of the chamber (2) and the space (22') or the pressure sink (5), which can be created or blocked by the control system, wherein g) the interior of the chamber (2') is formed between a bell (14') and at least one support or bearing element (23') for the at least one object (3'), wherein the bell (14') and the at least one support or bearing element (23') are designed and controlled by the control system to be movable relative to one another and in a coordinated manner such that h) the bell (14') and the support or bearing element (23') are brought into pressure-tight contact with one another to seal the interior of the chamber (2') in a pressure-tight manner, and i) the bell (14') and the support or bearing element (23') are brought out of contact to at least partially create the second connection between the interior of the chamber (2') and the space (23') or the pressure sink. device according to claim 14 , characterized in that the support or bearing element (23') comprises a conveyor belt of a conveying direction on which the at least one object (3') can be conveyed, and that the bell (14') can be controlled in a coordinated manner by the control system between a position lowered onto the conveyor belt, in which a bell edge (16') of the bell (14') makes sealing contact with the conveyor belt, and a position raised from the conveyor belt, in which the bell edge (16') of the bell (14') is out of contact with the conveyor belt. device according to claim 15 , characterized in that a) the bell (14') forms a chamber wall of the chamber (2') and the space (22') or the pressure sink is formed outside the bell (14') and is delimited by the bell (14'), a housing (7') and the conveyor belt in the position of the bell (14') lowered onto the conveyor belt, the bell (14') being guided on the housing (7') in a movable and coordinated manner relative to the conveyor belt by the control system, and in that b) the at least one object (3') can be transported by means of the conveyor belt through a closable feed opening (18') of the housing (7') into the interior of the housing and through a closable discharge opening (21') of the housing (7') out of the interior of the housing (7'). Device according to one of the Claims 14 until 16 , characterized in that the support or bearing element comprises a construction platform (13') on which the at least one object (3') has been additively produced. Device according to one of the Claims 14 until 17 , characterized in that the bell (14') comprises a construction container in which the at least one object (3') has been additively produced.

Images