EP3475015A1

EP3475015A1 - Powder drying in generative production

Info

Publication number: EP3475015A1
Application number: EP17733423.2A
Authority: EP
Inventors: Joachim BEHM
Original assignee: Trumpf Laser und Systemtechnik GmbH
Current assignee: Trumpf Laser und Systemtechnik GmbH
Priority date: 2016-06-24
Filing date: 2017-06-22
Publication date: 2019-05-01
Also published as: WO2017220744A1; DE102016111660A1; CN109475937A

Abstract

A production device (1) for the generative production of a three-dimensional component (3) from a powder (5) has a production space (11), which provides a working surface (21) and comprises a building platform area (23A) and a powder reservoir area (23B). The production device (1) also has a spraying source (51) for producing a jet for spraying powder (5) in the building platform area (23A) for producing the component (3) layer by layer, a powder storage container (25) for providing the powder (5) through a providing opening (21B) in the working area (21) into the powder reservoir area (23B) and a pushing device (19) for transferring the powder from the powder reservoir area (23B) into the building platform area (23A). The production device (1) also has a gas system (41), for example a gas circulating system, for providing a drying gas stream (40), which flows via the providing opening (21B) in the working surface (21) for taking up moisture from an uppermost layer of powder (5A).

Description

POWDER DRYING IN GENERATIVE MANUFACTURING

The present invention relates to an apparatus for laser-based additive manufacturing, and more particularly to the provision of dry powder for additive manufacturing. Furthermore, the invention relates to a method for drying powder for the additive production of a component in a generative manufacturing apparatus.

The laser-based additive production of, in particular metallic or ceramic, workpieces is based on solidification of a starting material in powder form by the irradiation with laser light. This concept - also known as Selective Laser Melting, Powder Bed Fusion or Laser Metal Fusion (LMF) - is used, among other things, in (metallic) 3D printing machines. An exemplary machine (herein LMF machine for producing three-dimensional products) is disclosed in EP 2 732 890 A1. The advantages of generative manufacturing are generally a simple production of complex and customizable parts. In this case, in particular defined structures in the interior and / or power flow optimized structures can be realized.

For a reproducible interaction of the laser light with the powder, inter alia, the state of the powder is important, since e.g. a varying water content in the powder can lead to different melting processes and thus to differently solidified material structures. The moisture content of the powder depends, among other things, on storage and weather conditions when the powder is loaded into the LMF machine. An increased moisture content may e.g. lead to increased porosity of the material (see, for example, "Formation and reduction of hydrogen porosity during selective laser melting of AlSilOMg", Weingarten et al., Journal of Materials Processing Technology 221 (2015) 112-12) of the powder can be reduced by too high a moisture content.

For drying the powder, various approaches are known. For example, an attempt is made to dry the powder before it is used in the machine, for example by using dry bags in the storage containers of the powder. However, this can have the disadvantage that the effect of

Desiccant degrades during long storage. Furthermore, the desiccant can accidentally get into the space. For example, EP 2 992 986 A1 discloses the use of a desiccant in the gas or powder cycle of an apparatus for producing SD components. Further, US 9,156,056 B2 discloses a drying unit for drying powder loaded in a storage tank by heating the storage tank. This procedure may have the disadvantage that the drying takes longer with increasing size of the reservoir. Thus, the ratio of the surface of the powder in the reservoir, which is directly exposed to the surrounding atmosphere and thus allows removal of moisture from the powder in the reservoir, to the total volume of the powder in the reservoir decreases.

Furthermore, EP 3 023 228 A1 discloses a machine for the generative fabrication of three-dimensional products on a platform which directs gas flow over the platform to remove e.g. Provides smoke from the interaction zone. Other gas cycle configurations are made of e.g. DE 10 2010 052 206 AI, DE 10 2006 014 835 AI and

WO 2010/007394 AI known. One aspect of this disclosure is based on the object of bringing the moisture content of the powder for the building application to a low, and if possible, during production substantially constant, level.

At least one of these objects is achieved by a manufacturing apparatus for the additive production of a three-dimensional component from a powder according to claim 1 and by a method for drying powder for the additive manufacturing according to claim 11. Further developments are specified in the subclaims.

In one aspect, a manufacturing apparatus for generatively producing a three-dimensional component from a powder includes a work space providing a work surface comprising a build platform area and a powder reservoir area, a beam source for generating a beam for powder irradiation in the build platform area for making the component in-layers; a powder reservoir for providing the powder through a supply port in the working surface into the powder reservoir region; a pusher for transferring the powder from the powder reservoir region to the construction platform region and a gas system for providing a drying gas stream across the supply port in the working surface to receive moisture from an uppermost layer of the powder flows. In some embodiments, the manufacturing apparatus further comprises a build cylinder having a lowerable die providing a platform for forming a powder bed and a component powder area defined by the platform connected to the build platform area through an irradiation opening in the work surface Gas system forms the drying gas flow substantially transversely to the alignment direction of the openings in the work surface.

Furthermore, the gas system may comprise an outlet opening structure, in particular arranged on or in a front wall or a door of the production apparatus, and a suction opening structure, in particular arranged on or in a rear wall of the production apparatus, wherein the outlet opening structure and the suction opening structure are arranged on opposite sides of the supply opening. The outlet opening structure and / or the suction opening structure may be designed such that a flow pattern of the drying gas stream in the powder reservoir region which is directed in the direction of the supply opening, in particular laminar, is formed. Furthermore, the gas system can be designed as a gas circulation system, which comprises a filter unit with a drying medium for removing moisture from the gas, and wherein the drying medium is arranged in particular in a replaceable, and for example separable via valves component in the gas cycle. In general, the gas system may further comprise a protective gas tank and / or an inert gas connection, a pump system, valves and / or lines for connecting the individual components of the gas circulation system, in particular comprising argon or nitrogen. The gas system can be subdivided into a main housing section, which is arranged below and behind the production space, for example, and a (door) section, for example integrated in a door.

In some embodiments, the gas system is configured to provide a particulate discharge gas stream, particularly parallel to the drying gas stream, extending above the irradiation port in the working surface for discharging particles from an interaction zone in the building platform region.

In some embodiments, the manufacturing apparatus further comprises a control unit for adjusting the drying gas flow and in particular the Partikelabführgasstroms and / or adjusting the position of the pusher during the irradiation process between the supply opening and the irradiation opening to the spatial Separating the drying gas flow from the building platform area and in particular the

Partikelabführgasstrom, and / or a heat radiator for generating a directed towards the supply opening, and in particular also to the irradiation heat radiation, wherein the heat radiator is further arranged in particular in the production space in the region above the supply opening. The heating from above has the advantage that substances adsorbed to the powder, such as water (moisture), in a top powder layer after heating, desorb faster and diffuse through the powder, so that the powder of the top powder layer is dried faster by the drying gas stream , Under special conditions, the underlying powder layers can (strongly) heat up in spite of the usually poor heat conduction properties of the powder in such a way that moisture increasingly diffuses out of them into the upper powder layer. In order to prevent or minimize this undesirable effect (in particular during a parallel production process), it is important to ensure that not too much heat is introduced into the upper powder layer. As a result, the advantageous effect of moisture removal (only from the upper layer), which saturates with increasing temperature, can be retained. Optimal heat input can be determined depending on the material, for example. In a further aspect, a method of drying powder for additive manufacturing includes the steps of providing a quantity of fresh powder above a supply port in a work surface and providing a drying gas stream that flows through the supply port in the work surface to receive moisture from an uppermost one Position of the powder flows.

The provision of the amount of fresh powder may be accomplished by gradually increasing a powder supply amount across the working surface through the supply port, providing the drying gas stream simultaneously with a powder irradiation process at an irradiation port, and / or the drying gas stream may be substantially transverse to the alignment direction of the openings in the working surface stream.

Further, the method may include a drying assisting step of heating the above-prepared supply amount of fresh powder from above, the heating particularly by irradiating heat radiation to the Provision opening, and in particular on the irradiation opening, can be done in the work surface for heating the uppermost layer of the powder.

An advantage of the concepts described herein is that drying can act almost immediately on the powder used to build up the subsequent layers. It is not absolutely necessary to dry the powder in the LMF machine or even for hours before, thus delaying the start of the production process.

In general, the concepts described herein may allow stabilization of the manufacturing process against variations in the humidity of the powder used. Furthermore, external drying times of the powder can be reduced or even completely eliminated. Thus, the concepts described herein may accelerate the start of production by rapidly drying the incrementally required quantities of powder by means of e.g. Argon streams allow, since the slow drying of the entire powder can be omitted.

Moreover, the structures described herein may allow a simple and rapid change of the drying medium in the gas cycle through the use of desiccant packages. For example, a change of desiccant packages within a minute or less.

The concepts described herein may further have the advantage that the drying process is parallel to the main time, i. at the same time as the construction phase, expires.

Herein, concepts are disclosed that allow to at least partially improve aspects of the prior art. In particular, further features and their expediencies result from the following description of embodiments with reference to the Figi ren. From the figures show:

1 shows a schematic spatial representation of an exemplary generative manufacturing device,

FIG. 2 shows a schematic sectional view of the generative production apparatus from FIG. 1 parallel to the XY plane through the production space, FIG.

FIG. 3 shows a schematic sectional view of the generative production apparatus from FIG. 1, parallel to the XZ plane through the production space, as indicated in FIG. 2, FIG. Fig. 4 is a schematic sectional view of the generative manufacturing apparatus of FIG. 1 parallel to the YZ plane through the production space as indicated in Fig. 2 and

5 is a sketch to illustrate an exemplary gas cycle of a generative manufacturing device.

Aspects described herein are based, in part, on the recognition that targeted drying of a topmost powder layer can be effected by a (e.g., dried argon) blanket gas stream. A complete and lengthy drying of the entire amount of powder (based on a diffusion of water vapor through the porosity in the powder bed) before, during or after the filling of the reservoir can be omitted when using such a surface drying stream.

An embodiment of an LMF machine designed to provide such a powder drying process integrated in the production process will be explained below with reference to FIGS. 1 to 4. Fig. 5 shows an exemplary gas cycle for use in such LMF machines.

FIG. 1 shows an exemplary generative production device 1 for producing an SD component 3 from a powder 5. For the production process, reference is made to the above-mentioned EP 2 732 890 A2. The manufacturing apparatus 1 comprises a main housing 11, which provides a production space 13. A front wall 15 limits the production space 13 on the front side. The main housing 11 further comprises a rear wall 18, side walls and a ceiling, which together define the production space 13. The front wall 15 has a front frame 15A with an opening 17, through which access to the production space 13 of the manufacturing device 1 is made possible. The opening 17 may be interrupted during the manufacturing process by e.g. on the front wall 15 attached door 31 (handle 31 A, shutter 31 B) are closed (see Fig. 2). With the door 31 open, there is access to the manufacturing space 13 of the manufacturing apparatus 1 (see Fig. 1) and an operator can e.g. Carry out the necessary preparatory steps such as cleaning the production space 13 and refilling the powder reservoir and remove the finished component 3.

Fig. 1 further shows a slider 19 (also referred to herein as a wiper) for distributing the powder 5 during the manufacturing process. The manufacturing process takes place on a work surface 21, which forms the bottom of the production space 13. The work surface 21 has a construction platform area 23A, a powder reservoir area 23B and (optionally) a powder collecting area 23C. The building platform area 23 A can be provided centrally with respect to the opening 17. In it, the irradiation process for the production of the 3D component 3 takes place. The powder reservoir region 23B serves to provide fresh powder 5A, which is transferred to the slide 19 for the manufacture of the 3D component 3 in the construction platform region 23A in a manner of one piece.

As shown in Fig. 2, the building platform portion 23A is arranged in the X direction (i.e., the opening 17 in the transverse direction) between the powder reservoir portion 23B and the powder collecting portion 23C. The powder reservoir area 23B has a e.g. cylindrical powder reservoir 25, the upper end of which opens into a (powder) supply opening 21B of the working surface 21. By means of a punch 25 A, for example, metallic or ceramic powder 5 can gradually be lifted from the powder reservoir 25 to above the working surface 21 (along arrow 26). If a new layer is required for irradiation, the slider 19 can be used to move the fresh powder 5A projecting beyond the working surface 21 laterally in the X-direction into the building platform area 23A. Accordingly, the slider 19 extends in Fig. 2 in the Y direction, which is orthogonal to the transverse direction (X direction) in the work surface 21. The build platform area 23A has a e.g. cylindrical construction cylinder 27 with a lowerable, a platform for forming a powder bed providing punch 27A. As a result of the lowering, a component powder region bounded by the platform is formed, which is connected to the building platform region 23A through the irradiation opening 21A in the working surface 21. If a layer of the component 3 has been formed by fusing powder 5, the punch 27A is lowered so that a recess defined by an irradiation opening 21A in the working surface 21 is formed, into which the fresh powder 5A can be displaced with the slide 19, so that a new upper powder layer is formed in the powder bed to be irradiated. Powder 5B not needed to build up the new layer can be moved with the slider 19 through an opening 21C of the working surface 21 in the powder collecting area 23C, e.g. be moved to a collection container for recycling.

The main housing 11 further comprises at least parts of a gas circulation system 41, such as a protective gas tank and / or an inert gas connection and a pump system (not shown) and a filter unit 71. The gas circulation system 41 allows the production space 13 to flood with eg inert gas such as argon or nitrogen during the manufacturing process. Further details of the gas circulation system 41 are explained below in particular in connection with FIG. 5. An irradiation system 51 can be mounted on the main housing 11, for example above the building platform area 23A. The irradiation system 51 is designed to generate radiation, for example laser light, which can fuse the powder 5 into material layers of a component 11. It is based for example on a fiber or disk laser system. Alternatively, laser light may be guided from such a source to the main body 11. The main housing 11 has a scanner system, which can guide the radiation in a matched to the component 3 path in the building platform area 23A for locally melting the uppermost powder layer of the powder bed.

As mentioned above, the parameters of the powder influence the interaction of the radiation / the laser light with the powder and thus the fusion of the powder grains. In particular, the moisture content of the powder affects the manufacturing process.

In order to reduce the moisture content of the powder 5 immediately before the interaction with the jet, the gas cycle system 41 is designed such that a surface drying flow 40 of the protective gas via / on the opening 21B of the working surface 21 and thus on / on the top powder layer of the powder reservoir 25 is directed. The protective gas is preferably "dried", for example it has a moisture content of less than about 0.0005 g / 1. Examples of dryable protective gases are argon and nitrogen The drying of the protective gas can be effected by passing the protective gas through or over a drying medium / Desiccant (eg anhydrone from LECO) in the gas circulation system 41 done.

In the embodiment shown, the drying gas stream 40 is formed substantially transversely to the direction of alignment (here, the X direction) of the openings 21A, 21B, i. He flows accordingly in the Y direction through the opening 21 A in the work surface 21st

The drying and the subsequent transfer of the dried gas over the uppermost powder layer in the powder reservoir 25 can be designed to dry just that small amount of powder (small compared to the total amount of powder in the powder reservoir 25), immediately following for the construction of the next layer of the component 3 is used with the laser beam. Since substantially only the upper layer of powder 5A is used in the next-layer reservoir, the amount of powder to be dried is small, so that the powder 5A can be sufficiently dried by the inert gas flowing along. In general, the drying before, during and / or after lifting the stamp 25 A, in particular permanently.

An exemplary realization of the desired flow course in the production space 13 can be effected by the gas circulation system 41 illustrated in FIGS. 1 to 4. In this case, the flow pattern is implemented by way of example in combination with a special flow pattern for Rußabfuhr, in which a (Rußabfuhr-) gas stream 42 from the door 31 to the rear wall 18 (or in the opposite direction) flows over the Bauplattformbereich 23 A. Here, carbon black is representative of minute particles that are involved in the interaction of e.g. Laser light can arise with the powder. In order to prevent an influence on the manufacturing process (deposition on optics or the component itself), these very small particles can be blown out of the interaction region by a corresponding flow and then sucked off.

The gas cycle system 41 comprises a main housing section 41A, which is arranged below and behind the production space 13, for example, and an door section 41B integrated in the door 31. The main body portion 41A includes e.g. the protective gas tank and / or the protective gas connection to an external source of protective gas, the pump system and the filter unit 71 of the gas circulation system 41.

The filter unit 71 is fluidly connected to a suction port structure 55 in the rear wall 18 via a conduit 46A. The suction port structure 55 is disposed near the work surface 21 in the area of the powder reservoir portion 23B. In Fig. 2, an extension of the Absaugöffnungsstruktur 55 in the building platform area 23 A is indicated by dashed lines.

Furthermore, the filter unit 71 is fluid-connected to an outlet opening structure 45 A in the door 31. For this purpose, the main housing portion 41 A of the gas circulation system 41 comprises a line 46 B to the front wall 15, which opens into a (housing) port 43 A in a region covered by the door 31 area. When the door 31 is closed, the connection opening 43 A is in fluid communication with the door portion 41 B of the gas circulation system 41 via a (door) connection opening 43 B. Accordingly, the door portion 41B includes the drying flow discharge port structure 45A, possibly a soot discharge flow outlet port structure 45B, the port 45A, and one or more communication lines 47 from the port 45A to the outlet ports 45A, 45B. In some embodiments, switchable valves or a plurality of connection openings may, for example, also be provided in order to be able to control the outflow of the protective gas from the outlet opening structures 45 A, 45 B. Furthermore, the outlet opening structure 45A and / or the suction opening structure 55 may be shaped in such a way that a flow path which is as laminar as possible (in the direction of the supply opening 21B) is as close as possible to the flow path

Powder reservoir region 23B is formed (see surface drying stream 40A in Fig. 4).

Generally, the gas circulation system 41 is configured to be on one side of the

Powder reservoir portion 23 B (dry) inert gas in the direction of the opening 21 B of the working surface 21 to flow out and on an opposite side to discharge the protective gas, wherein the protective gas has absorbed some moisture from the powder 5 A (if the powder is "wet" 5A). In this way, a (possibly previously dried) gas stream can be passed over the powder reservoir in the reservoir, which dries a thin layer of powder on the surface of the powder reservoir

Powder reservoir portion 23B and possibly due to the special shape of the surface drying stream 40 can be formed uniformly, so that a uniformly drying the entire surface of the current over the powder 5 A is performed. This can allow uniform drying of the topmost layer of powder during the manufacturing process. In other words, at the same time as drying, a powder layer-correspondingly dried and distributed-can be exposed in the construction cylinder 27 in order to sinter the 3D component 3 in layers, i. melt the powder layer by layer.

For the exposure of the next layer, the powder dried during the preceding layer formation is distributed by the slide 19 onto the previously irradiated and lowered powder surface in the construction cylinder 27. While the next layer of the component 3 is produced from this, the next quantity of powder can be dried again at the same time.

In Fig. 2, a heat radiator 59 is also shown schematically, which is directed to the opening 21 B in the work surface 21 and can support the drying process. Wärmestrah- Ler 59 is designed for heating the powder from above. In addition, it can also be used for the preheating of the powder in the region of the opening 23A.

Furthermore, the slide 19 can be shaped in this way or be positioned during the drying in such a way that results in the most uniform possible drying of the powder surface. For example, during irradiation, the slider 19 may be positioned in a waiting position between the powder reservoir portion 23B and the build platform portion 23A (see FIG. 2) so as not to affect the different drying and soot discharge currents. Furthermore, the respective currents can be activated, reduced or completely suppressed as a function of the current method step.

As previously exemplified, the implementation of the concepts disclosed herein into the inert gas purge of the overall system, particularly the inert gas purge of at least a majority of the manufacturing space, may be integrated throughout the manufacturing process. In summary, a dry gas stream is deliberately passed over the powder to be dried. As explained above, the protective gas can circulate in a gas circulation in which the gas stream is dried with a desiccant and possibly additionally cleaned with a filter for the separation of very small particles / suspended matter such as soot Alternatively, the gas stream may be part of a higher level gas drying and purification process, ie, dry gas is supplied and the humidified gas is fed to a central treatment.

In Fig. 5, a gas cycle is shown schematically. One recognizes a drying protective gas stream 81 A and (dashed) an optional soot-discharging protective gas flow 81B through the schematically shown production space 13. Via gas lines 52 the moist (and possibly soot-containing) protective gas is fed to the filter unit 71.

The filter unit 71 has a Feinstfüter 73 for removing particles from the gas stream. Subsequent drying of the gas stream takes place by transfer via a drying medium in a preferably easily replaceable component, for example a pipe 75. The pipe 75 can be separated from the gas circulation by valves 77 at both ends, for example, so that the drying medium used is exchanged easily and quickly can be. In general, care must be taken that the drying medium does not contaminate the powder 5 in the production space 13. This can be avoided, for example, with a further filter (not shown) or with correspondingly fine-pored packaging of the drying medium. The cleaned and dried gas stream is then returned via lines 52 and possibly valves 79 in the production room 13. If the gas flow is supplied to different areas, the valves 79 for adjusting the flow paths and the flow rates can be controlled by a control unit (not shown). The gas streams for drying and removal of soot can thus be integrated or formed separately from one another.

Furthermore, as already mentioned above, for spatially separating the gas stream for drying from the gas stream for removing soot, the slide 19 can also be controlled by the control unit during irradiation to take a waiting position between the storage container and the building cylinder, for example.

The tube with the drying medium can be installed both upstream of the superfine filter 73 for Rußabschei- tion, as well as after this filter. In the former case, no additional retention filler for the drying medium is necessary.

Alternatively to the use of a drying medium, the moisture may e.g. be removed from the gas stream by a cold trap in the filter unit 71.

LMF machines in which the concepts described herein can be used include, for example, the systems "mysint 100", "TruPrint 1000" and "TruPrint 3000".

It is explicitly pointed out that all features disclosed in the description and / or the claims are considered separate and independent of each other for the purpose of original disclosure as well as for the purpose of limiting the claimed invention independently of the feature combinations in the embodiments and / or the claims should. It is explicitly stated that all range indications or indications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, in particular also as the limit of a range indication.

Claims

claims

1. manufacturing device (1) for generative production of a three-dimensional component (3) from a powder (5) with

a production space (11) providing a work surface (21) comprising a building platform area (23A) and a powder reservoir area (23B),

a beam source (51) for generating a beam for the irradiation of powder (5) in the building platform area (23 A) for the layered production of the component (3),

a powder reservoir (25) for supplying the powder (5) through an opening (21B) in the work surface (21) into the powder reservoir area (23B),

a sliding device (19) for transferring the powder from

Powder reservoir area (23B) in the building platform area (23 A) and

a gas system (41) for providing a drying gas flow (40) flowing via the supply port (21B) in the working surface (21) for receiving moisture from an uppermost layer of the powder (5A).

2. Manufacturing apparatus (1) according to claim 1, further comprising

a building cylinder (27) having a lowerable platen (27A) providing a platform for forming a powder bed and a component powder area bounded by the platform, passing through an irradiation opening (21A) in the work surface (21) with the building platform area (23 A) is connected,

wherein the gas system forms the drying gas flow (40) essentially transversely to the line-up direction of the openings (21A, 21B) in the working surface (21).

3. Manufacturing apparatus (1) according to claim 1 or 2, wherein the gas system (41) comprises: an outlet opening structure (45 A), in particular arranged on or in a front wall (15) or a door (31) of the manufacturing apparatus (1), and

a suction opening structure (55), in particular arranged on or in a rear wall (18) of the production apparatus (1),

wherein the outlet port structure (45A) and the suction port structure (55) are disposed on opposite sides of the supply port (21B).

4. Manufacturing device (1) according to claim 3, wherein the outlet opening structure (45 A) and / or the Absaugöffnungsstruktur (55) are formed such that in a direction Provision opening (21 B) directed, in particular laminar, flow path of the drying gas stream (42) in the powder reservoir region (23 B) is formed.

5. Manufacturing apparatus (1) according to one of the preceding claims, wherein the gas system (41) is further formed as a gas circulation system comprising a filter unit (71) with a drying medium for removing moisture from the gas, and

wherein the drying medium is arranged in particular in a replaceable, and for example via valves (77) separable component (75) in the gas circulation.

6. manufacturing apparatus (1) according to one of the preceding claims, wherein the gas system (41) further comprises

a protective gas tank and / or an inert gas connection,

a pump system,

Valves and / or

Lines for connecting the individual components of the particular argon or

Nitrogen leading gas circulation system.

7. Manufacturing device (1) according to one of the preceding claims, wherein the gas system (41) in a main housing portion (41 A), for example, below and behind the production space (13) is arranged, and one, for example, in a door (31) integrated, (Door) section (41B) is divided.

8. Production device (1) according to one of the preceding claims, wherein the gas system (41) further for providing a, in particular parallel to the drying gas flow (40) flowing Partikelabführgasstroms (42) is formed, which extends over the irradiation opening (21A) in the work surface (21) for removing particles from an interaction zone in the building platform area (23 A) extends.

9. Manufacturing apparatus (1) according to one of the preceding claims, further with

a control unit for adjusting the drying gas flow (40) and in particular the Partikelabführgasstroms (42) and / or

for adjusting the position of the pushing device (19) during the irradiation process between the supply opening (21B) and the irradiation opening (21A) for spatially separating the drying gas stream (40) from the building platform region (23 A) and in particular the Partikelabführgasstrom (42).

10. Manufacturing apparatus (1) according to one of the preceding claims, further with

a heat radiator (59) for generating a heat radiation directed to the supply opening (21B), and in particular also to the irradiation opening (21A),

wherein the heat radiator (59) is further arranged in particular in the production space (11) in the region above the supply opening (21B).

11. Process for drying powder (5) for additive production with the steps:

Providing a quantity of fresh powder above a supply opening (21B) in a work surface (21) and

Providing a drying gas stream (40) which flows via the supply opening (21B) in the working surface (21) for receiving moisture from an uppermost layer of the powder (5A).

12. The method of claim 11, wherein

providing the amount of fresh powder by gradually increasing a powder supply amount across the work surface (1) through the supply port (21B), providing the drying gas stream (40) at the same time as a powder irradiation operation at an irradiation port (21A), and / or

the drying gas flow (40) flows essentially transversely to the direction of arrangement of the openings (21A, 21B) in the working surface (21).

13. The method according to any one of claims 11 or 12, further comprising the step supporting the drying process:

Heating the above provided the supply opening (21B) amount of fresh powder (23B) from above, in particular by irradiating heat radiation to the supply opening (21B), and in particular also to the irradiation opening (21A), in the working surface (21) for heating the top layer of the powder (5A).