Drying device for a powdered build material, and installation for producing three-dimensional components

A drying device for a powdered building material, in particular for a building station, unpacking station and/or sieve station which can be combined to form an installation for producing three-dimensional components by layer-by-layer solidification by means of a beam acting on the powdered building material, having a container which has a container base and, opposite the container base, a container opening, having a connection flange which has a fastening portion for releasably receiving the container opening of the container, having a connection portion which is located opposite the fastening portion of the connection flange and has a through-opening, having a membrane which closes the through-opening and can be connected to the connection portion, having a retaining element arranged in the container, by means of which retaining element drying agent stored in the container is held separate or remote from the membrane, and a drying space which receives the drying agent and a free space arranged between the retaining element and the membrane is formed.

This application claims priority of German Application No. 10 2021 119 308.7, filed Jul. 26, 2021, which is hereby incorporated herein by reference in its entirety.

The invention relates to a drying device for a powdered building material, in particular for a building station, unpacking station and/or sieve station which can be connected together to form an installation for producing three-dimensional components by selective solidification by means of a beam acting on the powdered building material. The invention relates further to an installation for producing a three-dimensional component by successive solidification by means of a beam acting on a powdered building material, which installation comprises at least one drying device in a building station, unpacking station and/or sieve station, and to a storage container.

An installation for producing three-dimensional components by successively solidifying layers of the powdered building material is known from DE 10 2019 130 951 A1. For supplying the installations with powdered building material, cartridges which feed fresh or cleaned building material to a feed station are known. In the feed station there is provided a storage funnel, via which the powdered building material is fed to a process chamber of the building station. The powdered building material that is not solidified in the production of the three-dimensional component is fed to an emptying station. The discharged powdered building material is fed to a cartridge again via a collecting funnel of the emptying station. An emptying station for discharging the unsolidified powdered building material is likewise provided in the unpacking station, wherein the unsolidified building material is again fed to a cartridge via a collecting funnel. In a sieve station, processed powdered building material can be fed via a cartridge. A storage funnel is preferably arranged upstream of the sieve station. The powdered building material cleaned by the sieve station can in turn be fed to a cartridge, for example via a collecting funnel. By means of this arrangement, a circuit for powdered building material can be created, so that processed and/or cleaned building material can be re-used and fed to the building station.

As a result of the removal of the three-dimensional component that has been produced from the process chamber of the building station and the feeding of the three-dimensional component into an unpacking chamber of the unpacking station and/or during handling of building material in the sieve station, the building material can come into contact with the atmosphere as a result of the interfaces and in particular can absorb ambient moisture. There is thus the risk of increased oxidation of the powdered building material. This can lead to increased brittleness on solidification of the powdered building material during production of the three-dimensional component. In addition, there can be a change in the flow behavior of the powdered building material the powder circuit as a result of the absorption of moisture.

The object underlying the invention is to propose a drying device for a powdered building material and also an installation, in particular for producing three-dimensional components by layer-by-layer solidification by means of a beam acting on the powdered building material, and also a storage container, by means of which a moisture content in powdered building material is reduced.

This object is achieved by a drying device for a powdered building material, which drying device comprises a container which has a container base and, opposite the container base, a closable container opening, and a connection flange which has a fastening portion for the releasable fastening of the container opening, and having a connection portion which is located opposite the fastening portion of the connection flange and has a through-opening and having a membrane which covers the through-opening and can be positioned at the connection portion of the connection flange, and having a retaining element which is arranged in the container and by means of which drying agent stored in the container is held separate or remote from the membrane, and a drying space which receives the drying agent and a free space provided between the retaining element and the membrane is formed.

Such a drying device can be connectable both to a storage container for storing powdered building material and to a storage funnel of a feed station or a collecting funnel of an emptying station in an installation for producing three-dimensional components. The construction of the drying device allows moisture transported by the powdered building material to pass through the membrane first into the free space. The moisture can then disperse throughout the free space and pass through the retaining element into the drying space. The moisture is adsorbed by the drying agent provided in the drying space. Moisture can thus be removed from one or more stations of the installation or from the storage container and collected in the drying device. A powdered building material with a low or reduced moisture content results in an increase in the process quality and also in the component quality.

Furthermore, it is preferably provided that the retaining element can be inserted in the container in a replaceable manner. The retaining element can preferably be removed from the container so that, when the drying agent is saturated with the absorbed moisture, the drying agent can easily be replaced. Alternatively, the drying agent can also be heated in a heat source, such as, for example, a microwave, so that it releases the moisture completely again. The drying agent can be used again.

It is preferably provided that the retaining element is in the form of a mesh, screen or in the form of a support structure with a moisture-permeable membrane. Such retaining elements are structurally simple and can easily hold the drying agent in position within the drying space in the container. The retaining element preferably has a cylindrical annular collar, so that the retaining element engages an inner circumferential wall of the container by friction and/or clamping. It is thus possible for the retaining element to be arranged in a secured position within the container in order to enclose a defined volume of the drying space.

According to a further preferred embodiment of the drying device, it is provided that at least one seal is provided between the container and the fastening portion of the connection flange. The interface between the container and the connection flange is thus sealed with respect to the surrounding area, so that no further moisture can enter from the surrounding area.

The membrane is advantageously held at the connection portion of the connection flange by a seal, in particular a flat seal. This permits easy installation and also easy replacement of the membrane.

The membrane is preferably in the form of a moisture-permeable membrane. It has in particular a high water vapor permeability and is impermeable to the powdered building material.

The container of the drying device is preferably formed, at least in some regions, of a transparent material. It is thus possible to monitor the state of the drying agent visually by means of a color indicator in the drying space of the container.

Furthermore, it is preferably provided that a fill quantity of drying agent is provided in the drying space in the container, so that at least one tenth of the volume of the drying space is free of drying agent. In particular in the case of a vertical orientation of the retaining element within the container, this allows the drying agent to accumulate in the drying space at the container circumferential wall and a free volume to form above the drying agent, within which the atmospheric moisture can disperse evenly and be absorbed by the drying agent. This arrangement provides an increased surface area of the drying agent for adsorption of the moisture.

Furthermore, it is preferably provided that there is provided as the drying agent a powdered, spherical or pebble-shaped material which takes up moisture by adsorption. Such a drying agent can typically be a so-called silica gel or zeolite.

The drying agent can indicate the absorption of moisture by a color change. It can thus easily be recognized visually that and/or to what extent moisture has been absorbed. Furthermore, the time for replacing the drying agent can also easily be recognized.

The object underlying the invention is further achieved by an installation, in particular for producing a three-dimensional component by layer-by-layer solidification by means of a beam acting on a powdered building material, which installation comprises a building station, unpacking station and/or sieve station, wherein the building station, unpacking station and/or sieve station comprises at least one feed station with a storage funnel, and/or an emptying station with a collecting funnel, wherein at least one drying device according to one of the preceding embodiments can be connected at least to the storage funnel and/or to the collecting funnel.

The moisture optionally entrained in the powdered building material can pass into the drying space via the membrane of the drying device and be adsorbed by the drying agent. The powdered building material is thereby guided past in the drying device, preferably without coming into direct contact with the drying device. The moisture optionally entrained in the powdered building material can thus be guided out of or discharged from the powdered building material. This increases the component quality, because increased oxidation of the powdered building material is reduced and brittleness in the component is thus also reduced. Furthermore, the process quality of such an installation is improved, because powder application in the process can be impaired considerably by moist powder material. A moisture-laden building material can additionally change the flow behavior in a disadvantageous manner by accumulating or forming bridges at individual locations. This can be avoided.

A housing of the storage funnel and/or of the collecting funnel advantageously has an opening which can be closed by the drying device by means of its membrane. This allows such a drying device to be connected easily to the storage funnel and/or the collecting funnel. In addition, improved moisture removal can be made possible by the direct connection to the housing.

The drying device is preferably provided at vertically oriented wall portions of the housing of the storage funnel and/or of the collecting funnel. This allows a free volume to be provided within the drying space in the container of the drying device above the drying agent, whereby an increased surface area for the absorption of moisture is provided and a more even distribution of the moisture above the drying agent is made possible.

In particular it is provided that the drying device is provided at vertically oriented wall portions of the housing adjoining or adjacent to a feed opening of the storage funnel and/or of the collecting funnel and/or is oriented towards the visible side of the building station, unpacking station and/or sieve station. The drying device associated with the feed opening makes it possible that powdered building material accumulating in the storage funnel and/or in the collecting funnel does not come directly into contact with the membrane. By orienting the drying device towards the visible side of the building station, unpacking station and/or sieve station, quick and easy monitoring and visual checking is made possible.

The object underlying the invention is further achieved by a storage container for transporting and storing powdered building material for an installation, in particular for producing a three-dimensional component by layer-by-layer solidification by means of a beam acting on the powdered building material, which storage container comprises a powder receiver which can be closed by a closure member, wherein the powder receiver and/or the closure member has at least one opening to which a drying device according to one of the above-described embodiments can be connected. The powdered building material can thus be provided with a low or reduced moisture content, because the moisture in the atmosphere precipitates at the powder particles of the building material and condenses out.

FIG.1shows, schematically, a side view of an installation10for producing a three-dimensional component12by successively solidifying layers of a powdered building material14. This installation10comprises, for example, a building station16and an unpacking station18. This building station16and the unpacking station18each comprise a housing19and are provided separately from one another. Alternatively, this building station16and the unpacking station18can also be provided in a common housing19of the installation10.

The building station16comprises a beam source21, for example in the form of a laser source. This beam source21emits a beam22, in particular a laser beam22, which is fed via a beam guide to a processing head26of a process chamber24. The beam22is directed via the processing head26onto the building material14. This processing head26can be arranged on a linear axis system. This linear axis system28can be in the form of a two-axis system, so that the processing head26is movable in the process chamber24in the X-/Y-plane parallel to and above a work surface31. Alternatively to the processing head26, a scanner device can also be associated with the process chamber24. The scanner device comprises a controllable scanner mirror by means of which the beam21is directed onto the building material14.

In the work surface31there is a building module33within which a substrate plate34is guided so as to be movable up and down. The three-dimensional component12is produced on this substrate plate34by selectively solidifying the powdered building material14.

Above the work surface31there is preferably provided an application and levelling device36. This application and levelling device36travels over the work surface31. In this manner, on the one hand the powdered building material14can be applied into the building module33and at the same time the excess building material14which has been applied can be discharged from the building module33in a collecting device46by the levelling device.

The building material14preferably consists of a metal powder or ceramics powder. Other materials which are suitable and employed for laser melting and/or laser sintering can also be used. The process chamber24is preferably hermetically sealed. For producing the three-dimensional component12, the process chamber is filled with protecting gas or an inert gas in order to avoid oxidation on melting of the building material14.

The building station16further comprises a powder storage device41. This powder storage device41has a powder storage funnel42which is preferably equipped with a fill level sensor in order to detect the stored level of building material14. Via a metering device43, a predetermined amount of building material14is removed from the powder storage funnel42and fed to the application and levelling device36in the process chamber24.

The building material14that has not solidified after the exposure process is transferred by means of the application and levelling device36into a collecting device46. This collecting device46preferably comprises a collecting funnel47, the opening of which is integrated in the work surface31or lies in the work surface31. This collecting device46feeds the processed building material14introduced via the application and levelling device36to a downstream metering device43.

Associated with this metering device43downstream is a connection point50of an emptying station51, which is provided for connection of a connecting device48to which a cartridge container49can be fastened. Via the metering device43, a predetermined amount of processed building material14is transferred into the cartridge container49.

A storage place54for further cartridge containers49and/or connecting devices48can be provided in the housing19of the building station16. Both filled and empty cartridge containers49can be stored in this storage place54.

“Fresh building material”14is understood as being building material14that is for the first time provided for the production of a three-dimensional component12and fed to the process chamber24for the process of producing the three-dimensional component12.

“Processed building material”14is understood as being powdered building material14that has been fed to the process chamber24and was not solidified by the selective solidification by means of the beam22. This unsolidified powdered building material14is guided out of the process chamber24by the application and levelling device36.

“Cleaned building material”14is understood as being building material14that, starting from processed building material, has been cleaned, for example in a sieve station. The processed building material is thereby freed of oversized impurities and the like. This cleaned building material can again be fed to the building station16for a work process.

The building station16can further comprise in the powder storage device41a connection point50of a feed station52for at least one connecting device48with the cartridge container49. This is shown herein below inFIG.5.

The unpacking station18comprises an unpacking chamber61in which the building module33, which for removal from the process chamber24is preferably closed by a cover, can be inserted in order subsequently to be emptied in the unpacking station18. The substrate plate34with the component12is removed from the building module33and cleaned of unsolidified building material14in the unpacking chamber61. The processed building material14which accumulates in the unpacking chamber61on a work surface31is transferred to a collecting device46, which can be configured analogously to the collecting device46of the building station16. Via the metering device43, processed building material14is fed to the connection point50of the emptying station51. A connecting device48which receives an empty cartridge container49can be fastened to the connection point50. This cartridge container49is filled with processed building material14.

Openings63with a glove port can be provided in the unpacking chamber61for freeing the component12of loose building material14and feeding the loose building material to the collecting device46. A suction device for cleaning the component12and/or the work surface31can also be provided.

The cartridge container49filled with the processed building material14is fed to a sieve station66. This sieve station66can be integrated in the unpacking station18. The sieve station66can also be integrated in the building station16. The sieve station66can further be arranged so that it is isolated and separate from the building station16and the unpacking station18. The building station16, the unpacking station18and the sieve station66can also form a common installation in a housing19.

The sieve station66comprises at least one connection point50for receiving the connecting device50at a feed station52, to which the connecting device48with the cartridge container49can be fastened. The processed building material14delivered by the cartridge container49through connecting device50is preferably fed by means of a metering device43, in particular a metering screw, to a sieve device67. This sieve device67comprises a sieve68which can preferably be excited by means of ultrasonic frequencies or low frequencies. The processed powdered building material14can thereby be cleaned. For example, coarse particles or oversized particles and/or impurities can be retained by the sieve68and transferred to an oversized-particle container69. The processed powdered building material14, which is free of oversized particles and/or impurities, is discharged as cleaned building material14via an outlet opening71. This further outlet opening71opens into a connection point50of an emptying station51, to which the connecting device48with an empty cartridge container49arranged thereon can be fastened. The cartridge container49serves to receive the processed and cleaned powdered building material14.

The connecting device48with the cartridge container48filled with the processed and cleaned building material14is then conveyed to the powder storage device41again in order to supply the powder storage device41with building material14.

The term “feed station”52is understood as meaning that the connecting device48with a cartridge container49filled with building material14can be connected to this feed station52so that the building material14provided in the cartridge container49can be fed to the respective station, in particular the building station16and the sieve station66.

The term “emptying station”51is understood as meaning that a connecting device48with an empty cartridge container49can be connected to this emptying station51in order to transfer processed and/or cleaned building material14into the cartridge container49. The processed and/or cleaned building material14can thus be guided out of the respective station, in particular the building station16, the unpacking station18and/or the sieve station66.

FIG.2shows the storage funnel42in perspective. This storage funnel42of the feed station52corresponds in construction to the collecting funnel47of the emptying station51. The following observations relating to the storage funnel42apply correspondingly to the collecting funnel47.

The storage funnel42comprises a feed opening131through which powdered building material14is fed to the storage funnel42. The metering device43is provided at the lower end (not shown) of the storage funnel42. At least one wall portion132is formed adjoining the feed opening131. This wall portion132is preferably oriented vertically. This wall portion132comprises an opening133. This opening133, which is shown inFIG.3, is closed by a drying device134. The drying device134is preferably arranged on the wall portion132in a detachable manner by fastening means136. The opening133is preferably provided adjoining the feed opening131or adjacent thereto. The drying device134is thus positioned at a distance from the metering device34. The powdered building material14transferred into the storage funnel42can accumulate above the metering device43. It is preferably provided that a fill level of the powdered building material is monitored by a fill level sensor137. There is thus at least a free volume138between the fill level sensor137and the feed opening131, in which free volume moisture which has been absorbed by the powdered building material14in preceding process steps can accumulate. This moisture can be guided out of the free volume138in the storage funnel42by the drying device134.

FIG.3shows a schematic sectional view of the drying device134according toFIG.2on an enlarged scale. The drying device134comprises a container141. The container141comprises a container base142and, on the opposite side to the container base, a container opening143. The drying device134further comprises a connection flange146, which has a fastening portion147by which the container opening134of the container141is releasably connected to the connection flange146. At least one seal148can be provided between the container opening141and the fastening portion147. A radially outwardly protruding annular collar157is advantageously provided at the container opening143. It is thus possible to provide defined contact and fastening of the container141with the container opening143relative to the fastening portion147. In addition, sealing faces on the container opening143and of the fastening portion147may also abut one another for the purpose of further sealing.

Opposite the fastening portion147, the connection flange146has a connection portion151by which the container141can be fastened to the wall portion132. Abutting this connection portion151there is provided a membrane152. A seal, in particular a flat seal153, is provided between the membrane152and the wall portion132. On the one hand, the membrane152is thereby held fixed to the connection flange151. On the other hand, the opening133is sealed with respect to the surrounding area. The opening133is closed by the membrane152.

A retaining element156is positioned in the container141. This retaining element156is in the form of a mesh, screen or in the form of a support structure with a membrane. The retaining element156preferably has an annular collar157, whereby the retaining element156can be fastened to an inside wall of the container141by clamping. By means of the retaining element156, the drying device134is divided into a drying space161and a free space162. Drying agent164is preferably provided in the drying space161(FIG.4). The retaining element156in the form of a screen or mesh has a mesh size which is smaller than the particle size of the drying agent164.

By means of the retaining element156arranged in a replaceable manner in the container141, the container141can easily be filled with drying agent164. Moist drying agent164can also easily be replaced. The free space162formed between the membrane152and the retaining element156is preferably smaller in volume than the drying space161.

FIG.4shows a schematic side view of the drying device134according toFIG.2. The container141is of transparent form at least in some regions, so that the drying agent164is visually accessible. Preferably the entire container141is of transparent form.

A fill quantity of drying agent164is provided in the drying space161, so that, in particular in the case of a horizontal orientation of the drying device134, a free volume remains in the drying space161above the drying agent164. For example, the fill quantity of the drying agent164can comprise half the volume in the drying space161according to line166. A larger fill quantity or a smaller fill quantity of drying agent164can also be provided. In any case, the fill volume of drying agent164does not correspond to the volume of the drying space161but is smaller, so that a free volume always remains above the drying agent164.

The above-described drying device134can further be provided at a closure member171or cover or a powder receiver173of a storage container172. The closure member171preferably has the opening133. This is positioned by the drying device134analogously to the opening133at the storage funnel42. Thus, moisture removal can likewise be provided on transportation or storage of the powdered building material14in the storage container172.

Furthermore, the opening133can be provided at the powder receiver173.

Furthermore, it can be provided that this drying device134is provided at a cartridge container49, in particular at a vertically oriented wall portion or at a base located opposite a cartridge opening.