Device and method for the directed application of gas to a build space for additive manufacturing

Abstract

The invention relates to a device for the directed application of gas to a build space for additive manufacturing. This comprises: - a process chamber which limits a build space and has a build platform extending in an X / Y plane, wherein a first boundary region of the build platform extending in the Y direction forms a gas supply side, and wherein a second end region of the build platform opposite the gas supply side in the X direction and extending in the Y direction forms a gas discharge side, - a first nozzle device which is arranged on the gas supply side directly adjacent to the build platform, and is designed to output a horizontal first gas flow flowing approximately parallel to the surface of the build platform in the X direction, and - a third nozzle device, which is arranged above the build platform in a vertical Z direction orthogonal to the X / Y plane and horizontally offset to the first nozzle device in the X direction, is directed towards the build platform, and is designed to output a third gas flow flowing towards the build platform, wherein the first and third nozzle devices are designed such that the first and the third gas flow form an overall gas flow which in the region of the build platform generates a substantially laminar flow from the gas supply side towards the gas discharge side.

Description

[0001] Device and method for directed gas exposure of a build space for additive manufacturing

[0002] The present invention relates to a device and a method for the directed gas exposure of a construction space for additive manufacturing.

[0003] 3D printing makes it possible to produce a wide variety of three-dimensional components with complex geometries. Three-dimensional workpieces are built up layer by layer. The construction is computer-controlled from one or more liquid or solid materials according to specified dimensions and shapes (CAD). During construction, physical or chemical curing or melting processes take place. Typical materials for 3D printing are plastics, synthetic resins, ceramics, and metals.

[0004] 3D printing refers to generative or additive manufacturing processes. The most important 3D printing techniques are selective laser melting (SLM) or laser powder bed fusion (LPBF), laser cladding (LA) and electron beam melting (EBM) for metals, and selective laser sintering (SLS) for polymers, ceramics, and metals.

[0005] In metalworking processes, the material is melted selectively or selectively, causing it to solidify in a different form. In this type of process, metal powder or metal wire is melted and solidified layer by layer, allowing a three-dimensional component to be generated. Due to the locally limited energy input via the laser beam, the size of the resulting melt pool is small. This makes it possible to create delicate structures. Corresponding processes are marketed commercially as Laser Engineered Net Shaping (LENS), Direct Metal Deposition (DMD), Laser Additive Manufacturing (LAM), Selective Laser Melting (SLM), or Laser Metal Deposition (LMD), among others.

[0006] In selective laser sintering (SLS / LMF), a layer of powder material is applied to a work surface (build platform). The loose powder is melted selectively or selectively by a laser beam. Depending on the material used, the powder particles are bonded within the layer and with the underlying layer. Two basic development directions can be distinguished for the production of metallic components. In addition to the direct solidification of metallic powder materials using laser radiation (direct metal laser sintering), the production of metallic components using a combination of SLS of plastic-coated metal powder with subsequent thermal treatment (IMLS) has become established early on.

[0007] Direct metal laser sintering (DMLS) uses either single-component or multi-component metal materials. In particular, DMLS multi-component powders consisting of various alloying elements are used. The low-melting component contained in the powder is melted by a laser beam and flows around the high-melting component, which serves as the structural element.

[0008] In Electron Beam Melting (EBM), the process is essentially the same as that of laser-based processes. Loose metal powder is melted in a powder bed or via a nozzle, or a wire, and then solidifies into the desired shape. The required energy is supplied by an electron beam. The process usually takes place in a suppression chamber flooded with inert gas.

[0009] In electron beam melting, similar to selective laser melting (SLM), high energy is applied, which melts the build material. The energy is not supplied by a high-power laser, but rather by a powerful electron beam, which is deflected and positioned using powerful magnetic coils. The electron beam melting process must take place under a high vacuum. This significantly limits the installation space of devices that use selective electron beam melting.

[0010] In recent years, processes have been developed to improve the processing of single-component metal materials. Such processes are commercially available, for example, under the name Selective Laser Melting (SLM).

[0011] In contrast to selective laser sintering (SLS), selective laser melting (SLM) uses a laser beam to deliver significantly more energy to the powder bed, creating a true melt in the affected areas. This results in a more homogeneous object with greater density than the SLS process.

[0012] Laser cladding is a type of welding process in which a workpiece is clad by applying and simultaneously melting almost any material. This can be done in powder form, e.g., as metal powder, or with a welding wire or strip. In laser cladding, a high-power laser serves as the heat source, primarily a diode laser or fiber laser, but previously also CO2 and Nd:YAG lasers. In laser cladding with powder, the laser usually heats the workpiece in a defocused manner and melts it locally. At the same time, an inert gas mixed with fine metal powder is introduced. The metal powder melts at the heated area and bonds with the metal of the workpiece. In addition to metal powder, ceramic powder materials, especially hard materials, can also be used. Laser cladding with wire or strip works analogously to the powder process, but with wire or strip as the filler material.

[0013] EP 3 015 197 B1 describes a device for manufacturing or repairing a three-dimensional object. The device comprises two inlet nozzles. A process gas is introduced into the build space or process chamber of the device via the inlet nozzles. The process gas is, in particular, a protective or inert gas.

[0014] WO 2017 013454 A2 discloses a device for additive manufacturing and a flow device for use with such a device. The flow device has a gas flow system for controlling the condensate generated during the laser melting process. This comprises a first gas nozzle with a plurality of gas outlets and a gas outlet with a gas inlet. The gas outlets and the gas inlet are arranged to generate a horizontal gas flow across a working surface of the powder bed formed on the build platform. The nozzle and the outlet are intended to generate a laminar flow with a flow direction from the nozzle to an outlet.

[0015] DE 11 2019 003 725 T5 describes an additive manufacturing device. It comprises a lower nozzle that expels an inert gas in a horizontal direction through a lower opening into a process chamber, an upper nozzle that expels the inert gas through an upper opening into the chamber, and an inclined nozzle that expels the inert gas in an obliquely downward direction from the upper portion of the first sidewall. The inclined nozzle comprises a first nozzle that forms a flow path extending in a first direction from the upper portion of the first sidewall to a lower portion of the second sidewall, through which the inert gas flows and expels the inert gas in the first direction, and a second nozzle that forms a flow path extending in a second direction from the upper portion of the first sidewall to an upper surface of the platform, through which the inert gas flows and expels the inert gas in the second direction.

[0016] WO 2020 041 438 A1 discloses a system and method for flow control for a system for additive manufacturing. This system comprises a lower gas supply device with a lower gas inlet with openings and an upper gas supply device with an upper gas inlet with openings. According to this document, a laminar flow is to be generated in the area of ​​a build platform.

[0017] US 9,592,636 B2 relates to a laminating molding device, wherein the laminating molding device comprises a chamber with an inert gas supply opening and an inert gas supply space for a separate smoke diffusion section.

[0018] EP 3 147 047 A1 discloses a device for producing a three-dimensional workpiece, wherein a process chamber has a first gas inlet (horizontal direction) and a second gas inlet (vertical direction). The second gas inlet is approximately trapezoidal in plan view and has a plurality of gas inlet openings to supply a build platform with gas as evenly as possible.

[0019] EP 1 839 781 B1 describes a device for producing objects by layering powdered material. Two shielding gas supply lines are provided. The shielding gas supply line opens into nozzles. The shielding gas supply line opens into several shielding gas inlets.

[0020] DE 10 2010 052 206 B4 discloses a device for producing three-dimensional objects. The device comprises a process chamber with a protective gas injection system and a protective gas extraction system, with protective gas circulating within the process chamber.

[0021] DE 10 2016 112 652 A1 discloses a metal 3D printer that uses the powder bed process. This metal 3D printer comprises a housing, a recoating head, a material supply device, a protective gas supply device, a table, and a laser irradiation device for sintering metal powder. The protective gas supply device has a first ejection connection arranged on one side of the recoating head. The protective gas is thus released at the recoating head into the forming chamber, flows along the powder bed to a first outlet connection, at which an intake device is provided. The recoating head can be moved over the powder bed, whereby the corresponding ejection connection is also moved. In order to ensure that a protective orTo ensure that an inert gas flow to the first intake port across the powder bed can be provided, a second exhaust port is fixedly arranged in the forming chamber so that a protective gas flow across the powder bed to the first intake port can be generated even when the recoating head is positioned remotely. This 3D printing device also has a third exhaust port, which is adjacent to the exhaust port but slightly higher on a side wall. The protective gas, in particular nitrogen gas, supplied from a third exhaust port prevents a decrease in the concentration of the nitrogen gas in the forming chamber.

[0022] DE 10 2016 121 770 A1 discloses a 3D printing device with vertically offset inflow elements for protective gas, allowing multiple vertically offset flow layers to be created in a process chamber of a device for the additive manufacturing of three-dimensional objects. According to one embodiment, the lowest inflow elements are oriented diagonally downwards.

[0023] DE 10 2008 030 186 A1 discloses another 3D printer with a process chamber for selective laser melting. The process chamber has an inlet and an outlet for a process gas. This inert gas is flowed over the surface of the component to be produced to prevent unwanted reactions in the melt pool. Additionally, a feed is provided for the introduction of a reactive gas. By introducing reactive gas, the composition of the component's surface can be changed.

[0024] DE 10 2018 215 301 A1 relates to a 3D printer with a flow device for generating a gas flow. The flow device is characterized by comprising multiple channels, each with a varying cross-section. These channels can be used to generate a homogeneous or inhomogeneous flow with turbulence.

[0025] 3D printing devices are known from the prior art that provide multiple nozzles to supply a build platform with process gas as evenly as possible. Active extraction devices are also known from the prior art.

[0026] Additive manufacturing processes utilize a powder bed, powder feeder, or wire feeder, with these starting materials then being melted and subsequently solidified using a laser beam, electron beam, plasma / arc. Furthermore, inert or active gases are used as process gases in additive manufacturing processes.

[0027] These processes attempt to mitigate critical influences and processes during energy input through appropriate measures. Examples include the use of a substrate plate on which the component is fixed, conducting the process under a protective gas atmosphere, and applying new scanning strategies for exposing the powder to laser energy.

[0028] One goal of the aforementioned additive manufacturing processes is to ensure the most efficient energy input possible, thus achieving a reliable manufacturing process and high component quality. The object of the present invention is to provide a device and a method for the directed gas exposure of a build space for additive manufacturing, which provides an improved protective gas atmosphere during the process.

[0029] A further object of the present invention is to provide a device and a method for the directed gas application to a build space for additive manufacturing, which ensure the most efficient energy input possible.

[0030] Furthermore, it is an object of the present invention to develop a device and a method for the directed gas exposure of a construction space for additive manufacturing, which enable a reliable manufacturing process so that a high component quality can be achieved.

[0031] Furthermore, it is an object of the present invention to provide a device and a method for the directed gas exposure of a construction space for additive manufacturing, which provides an alternative to devices and methods known from the prior art.

[0032] One or more of these objects are achieved by the features of independent patent claims 1, 10 and 12. Advantageous embodiments are specified in the dependent subclaims.

[0033] According to the invention, a device for the directed gas application to a build space for additive manufacturing is provided. This device comprises: a process chamber defining a build space and having a build platform extending in an X / Y plane, wherein a first edge region of the build platform extending in the Y direction forms a gas supply side, and wherein a second end region of the build platform, opposite the gas supply side in the X direction and extending in the Y direction, forms a gas discharge side; a first nozzle device arranged on the gas supply side immediately adjacent to the build platform and configured to discharge a horizontal first gas stream flowing approximately parallel to the surface of the build platform in the X direction; and a third nozzle device.which is arranged in a vertical Z-direction orthogonal to the X / Y plane above the build platform and in the X-direction horizontally offset in the flow direction of the first gas stream from the first nozzle device, and is directed towards the build platform, and which is designed to emit a third gas stream flowing in the direction of the build platform, wherein the first and the third nozzle devices are designed such that the first and the third gas stream form an overall gas stream which generates a substantially laminar flow in the region of the build platform from the gas supply side towards the gas discharge side. By virtue of the fact that the first nozzle device is arranged on the gas supply side immediately adjacent to the build platform and emits a horizontal gas stream flowing approximately parallel to the surface of the build platform in the X-direction, and by virtue of a third nozzle device,which is arranged in a vertical Z-direction orthogonal to the X / Y plane above the construction platform and in the X-direction horizontally offset from the first nozzle device and emits a third gas stream flowing in the direction of the construction platform, a total gas flow is formed which generates a substantially laminar flow in the region of the construction platform from the gas supply side towards the gas discharge side.

[0034] Because the third nozzle assembly is offset from the flow direction of the first gas stream and aligned toward the build platform, the third gas stream pushes the first gas stream against the build platform. This allows the first gas stream to flow reliably and laminarly over a much larger area than if it were not exposed to the third gas stream.

[0035] This offset is at least 20% or at least 30% or at least 40% or at least 50% of the total length of the powder bed in the flow direction of the first gas stream.

[0036] By providing such a laminar overall gas flow, which flows horizontally parallel to the build platform, a constant laminar flow is created, providing an optimal protective gas atmosphere for process control. This minimizes or eliminates turbulence in the area of ​​the build platform where the additive manufacturing process takes place. Furthermore, gas consumption is significantly reduced.

[0037] In this way, efficient energy input during the production of a component is possible.

[0038] This makes the manufacturing process safer and makes it possible to achieve high component quality.

[0039] Preferably, the device can have a second nozzle device which is arranged in the vertical Z direction above or above the first nozzle device and below the third nozzle device, and is directed towards the construction platform, and which is designed to emit a second gas flow flowing in the direction of the construction platform, which second gas flow is a component of the overall gas flow, and wherein the second nozzle device is designed such that, in conjunction with the first and the third nozzle device, the first, the second and the third gas flow and thus the overall gas flow generate a substantially laminar flow in the region of the construction platform.

[0040] By providing the second nozzle device, the advantages explained above with reference to the device according to the invention are further optimized, since a total gas flow flowing parallel to the construction platform is further improved with regard to avoiding turbulence and providing a constant laminar flow.

[0041] The first nozzle device can extend approximately over 70% to approximately 100% or 110% or 120% of a total width of the construction platform in the Y direction and can comprise between one and eight first nozzle elements, in particular conically widening in the Y direction, each with a flow channel, which form the first nozzle device.

[0042] Because the first nozzle device extends approximately over the entire width of the build platform in the Y-direction, it is possible to constantly supply the build platform with gas in the Y-direction.

[0043] At least one flow channel of the first nozzle device extends approximately parallel to the build platform.

[0044] The second nozzle device can extend approximately over 80% to approximately 100% or 110% or 120% of a total width of the construction platform in the Y direction and can comprise between one and eight second nozzle elements, in particular conically widening in the Y direction, each with a flow channel, which form the second nozzle device.

[0045] By providing several nozzle elements, corresponding machining heads with swivel arms of a device for additive manufacturing are only slightly impaired when moving within the build space, or there is enough space for almost free movement of the machining heads.

[0046] Because the second nozzle device extends over approximately the entire width of the build platform, it is possible to expose the entire surface of the build platform to a laminar gas flow.

[0047] At least one flow channel of the second nozzle device can be inclined at an acute angle of at least 5° and a maximum of 45° relative to the build platform.

[0048] Such an arrangement of the at least one flow channel or the flow channels of the second nozzle device supports or improves the formation of a laminar flow of the overall gas flow.

[0049] The third nozzle device can extend approximately from 40% to approximately 100%, 110%, or 120% of the total width in the Y direction of the build platform and comprise between two and eight third nozzle elements, particularly those that widen conically in the Y direction, each with a flow channel, forming the third nozzle device. The third nozzle device also contributes to applying the most laminar flow possible to the build platform using the overall gas flow.

[0050] At least one flow channel of the third nozzle device can be inclined at an acute angle of at least 30° and a maximum of 90° relative to the build platform.

[0051] Such an orientation or alignment of the flow channel(s) improves the laminar flow of the overall gas flow in the area of ​​the build platform.

[0052] The device may comprise at least one gas supply device which opens via a branch into three lines which are each connected to the first, second and third nozzle elements via distribution channels, wherein flow control elements may be arranged in the three lines and / or in the distribution channels and / or wherein cross-sectional areas of the lines of the distribution channels may be designed such that all nozzle elements of the respective nozzle device output approximately the same volume flow of process gas.

[0053] Because all nozzle elements of the nozzle directions can be supplied with essentially the same volume flow of gas, the formation of a laminar overall gas flow is supported or improved.

[0054] In order to design the cross-sectional areas of the distribution channel accordingly, it can be provided, for example, that nozzle elements arranged adjacent to or at a shorter distance from the gas supply device are subjected to a low flow resistance and thus to a lower flow velocity in the corresponding sections of the distribution channel.

[0055] For nozzle elements located further away from the gas supply device, the opposite is true. These exhibit higher flow resistance and are therefore subjected to a higher flow velocity.

[0056] Means for designing the distribution channel accordingly can be realized by cross-sectional constrictions, resistance elements and / or the surface properties of the distribution channel.

[0057] The crucial point is that all flow channels emit a gas stream at approximately the same speed.

[0058] The device may comprise a suction device which is arranged on the gas discharge side immediately adjacent to the construction platform and which is designed to discharge the total gas flow and which extends approximately over 50% to approximately 100% of a total width in the Y direction and is preferably designed as a single suction nozzle element.

[0059] Because the total gas flow is discharged from the process chamber at the gas discharge side, no additional turbulence is created in the area of ​​the gas discharge side and it is possible for the total gas flow to flow laminarly and parallel to the surface of the build platform from the gas supply side to the gas discharge side.

[0060] The build platform can extend in the X-direction over a length of approximately 0.5m to 2m.

[0061] The build platform can extend in the Y direction over a length of approximately 0.7m to 2.5m.

[0062] The gas supply device can be designed such that the nozzle devices discharge the process gas at a speed of at least 1 m / s to approximately 3 m / s and preferably of approximately 2 m / s.

[0063] Such a flow velocity has proven to be advantageous with regard to the formation of a laminar overall gas flow.

[0064] Argon or nitrogen can be used as protective gas and / or functional gas.

[0065] According to a preferred embodiment, it can be provided that the gas supply device opens via a branch into three lines, which are each connected accordingly to the first, second and third nozzle devices.

[0066] It is provided that all first nozzle elements of the first nozzle device, all second nozzle elements of the second nozzle device and all third nozzle elements of the third nozzle device are each supplied with approximately a different volume flow of process or functional gas and / or protective gas via the three lines, so that the individual nozzle elements of the first, second and third nozzle devices each output approximately the same volume flow.

[0067] For this purpose, a first, second, and third flow control element or a component for controlling the flow of gases, such as a valve or flap, can be arranged in each of the lines to control the gas flow of the first, second, and third nozzle elements such that all nozzle elements of a nozzle device each output approximately the same volume flow. In this way, all nozzle elements together can output a roughly uniform total gas flow of 2 m / s, since, for example, the nozzle elements further away from the edge area are subjected to a lower volume flow of gas but at a higher flow velocity due to the higher flow resistance in the corresponding line.

[0068] This means that all three nozzle elements emit a gas stream with a flow velocity of approximately 2m / s.

[0069] According to this embodiment, the first, second, and third nozzle devices can be supplied with gas from a lateral edge region of the device via the distribution channel and the lines. Supplying the nozzle device from the edge region enables a space-saving and compact design and, in particular, easier assembly of the device 1.

[0070] It is therefore provided that the nozzle elements arranged in the edge region have a lower flow resistance than the other branches due to the flow control elements 37, 38, 39, so that the nozzle elements arranged in this region are subjected to a lower flow velocity.

[0071] One or more flow measuring devices (not shown) can be arranged in the build space in the area of ​​the build platform. The flow measuring device(s) is / are designed to measure whether laminar flow exists in the build space in the area slightly spaced from the build platform in the Z-direction.

[0072] Furthermore, a control device (not shown) can be provided which is connected to the flow control elements and to the flow measuring device(s) and which, on the basis of the corresponding flow values, controls the flow control elements accordingly and thus controls the volume flow from the first, second and third nozzle elements in such a way that a laminar, uniform flow is present in the area of ​​the construction platform.

[0073] Furthermore, according to the invention, a device for additive manufacturing is provided with a device as described above for the directed gas exposure of a construction space, wherein processing heads including swivel arms are preferably round in cross-section in order to reduce turbulence in the process chamber.

[0074] By providing processing heads and swivel arms with a round cross-section, turbulence within the process chamber is further reduced, and the overall laminar gas flow is only slightly impaired. The advantages of the inventive device for additive manufacturing are analogous to those described above with reference to the inventive device for directed gas application to a build space.

[0075] At least one nozzle device of the device for the directed gas application to a construction space can be manufactured by means of an additive manufacturing process.

[0076] By using an additive manufacturing process to produce a nozzle element or nozzle devices, these can be manufactured with any geometry and easily and cost-effectively.

[0077] In addition, the invention provides a method for the directed gas supply to a build space for additive manufacturing with a device for the directed gas supply to a build space as described above, wherein a process chamber delimiting a build space has a build platform extending in a horizontal X / Y plane, and wherein a first end region of the build platform extending in the Y direction forms a gas supply side, and wherein a second end region of the build platform opposite the gas supply side in the X direction and extending in the Y direction forms a gas discharge side, and a first nozzle device which is arranged on the gas supply side immediately adjacent to the build platform and which discharges a horizontal first gas stream flowing approximately parallel to the surface of the build platform in the X direction, and a third nozzle device,which is arranged in a vertical Z-direction orthogonal to the X / Y plane above the construction platform and in the X-direction horizontally offset in the flow direction of the first gas stream from the first nozzle device, and is directed towards the construction platform and which emits a third gas stream flowing towards the construction platform, wherein the first and the third gas stream emit a total gas stream which generates a substantially laminar flow in the region of the construction platform from the gas supply side towards the gas discharge side.

[0078] The advantages of the method according to the invention correspond analogously to those described above with reference to the device according to the invention for the directed gas exposure of a construction space.

[0079] The device can have a second nozzle device, which is arranged in the vertical Z-direction above the first nozzle device and below the third nozzle device, and is directed towards the build platform, and which emits a second gas stream flowing towards the build platform, which is a component of the overall gas stream, and wherein the first, second, and third gas streams, and thus the overall gas stream, generate a substantially laminar flow in the region of the build platform. The device can have at least one gas supply device for supplying the nozzle devices with a gas stream, which is connected to the nozzle devices via a branch and three lines and distribution channels, and wherein cross-sectional areas of the distribution channels and / or the lines are designed and / or have flow control elements such that nozzle elements of the nozzle devices emit approximately the same volume flow of process gas.

[0080] The total gas flow and thus the gas flows of the individual flow channels of the nozzle elements can have a flow velocity between 1 m / s and 3 m / s.

[0081] The total gas flow can thus have a flow velocity of at least 1 m / s or 1.2 m / s or 1.4 m / s and a maximum of 3 m / s or 2.5 m / s and in particular of 2 m / s.

[0082] The present invention is described in more detail below with reference to an exemplary embodiment illustrated in the figures. These show:

[0083] Figure 1 is a perspective view of a device according to the invention for the directed gas application to a construction space of a process chamber for additive manufacturing,

[0084] Figure 2 is a side view of the device of Figure 1,

[0085] Figure 3 is a perspective view of nozzle devices of the device and the process chamber of the device,

[0086] Figure 4 shows the nozzle arrangement from Figure 3 in a side view, and

[0087] Figure 5 shows the nozzle view from Figure 3 in a top view.

[0088] According to the invention, a device 1 for the directed gas exposure of a construction space 2 of a process chamber 3 for additive manufacturing is provided (Figures 1 - 5).

[0089] In the process chamber 3, a construction platform 5 extending in an X / Y plane 4 for additive manufacturing is arranged.

[0090] A first end region 7 of the build platform 5 extending in the Y direction 6 forms a gas supply side 8. A second end region 10 of the build platform 5, opposite the gas supply side 8 in the X direction 9 and extending in the Y direction 6, forms a gas discharge side 11.

[0091] Furthermore, the device comprises a first nozzle device 12. The first nozzle device 12 is arranged on the gas supply side 8 directly adjacent to the construction platform 5.

[0092] The first nozzle device 12 extends in the Y-direction 6 and, according to this exemplary embodiment, comprises five first nozzle elements 13. Each of the nozzle elements 13 is designed to widen conically in the X-direction 9 and has a uniform or constant cross-section in the Y-direction 6.

[0093] Furthermore, each of the first nozzle elements 13 forms a first flow channel 14 which is arranged approximately parallel to the surface of the construction platform 5 in the X-direction 9 and is designed to discharge a first gas stream 15 flowing in the X-direction 9.

[0094] The first nozzle elements 13 of the first nozzle device 11 or their first flow channels 14 are designed to discharge the horizontal first gas flow 15 flowing in the X direction 9 parallel to the surface of the construction platform 5.

[0095] Furthermore, a second nozzle device 16 is provided, which is arranged in a vertical Z-direction 17 above or above the first nozzle device 12.

[0096] According to the present embodiment, the second nozzle device 16 comprises five second nozzle elements 18, each forming a second flow channel 19.

[0097] The second nozzle elements are conically widening in the X direction 9 and have an approximately constant cross-section in the Y direction 6.

[0098] The second nozzle elements 18 of the second nozzle device 16 are inclined at an angle of approximately 5° relative to the X / Y plane 14 or relative to the construction platform, so that a second gas flow 20 is discharged via the second flow channels 19 and is directed in the direction of the construction platform 5.

[0099] In addition, the device comprises a third nozzle device 21, which is arranged in the vertical Z direction 17 orthogonal to the X / Y plane 4 above or above the build platform 5 and the second nozzle device 16 and in the X direction 9 horizontally or offset from the first nozzle device 12. According to the present exemplary embodiment, the third nozzle device 21 also comprises five third nozzle elements 22. The third nozzle elements 22 each have a third flow channel 23, wherein the third nozzle elements 22 or the third flow channels 23 are arranged at an angle of approximately 60° relative to the X / Y plane 4 or the build platform 5.

[0100] The third nozzle elements 22 are designed to widen approximately conically in the X direction 9 and have an approximately constant cross section in the Y direction 6.

[0101] A third gas stream 24 flowing in the direction of the construction platform 5 is discharged via the third nozzle elements 22 of the third nozzle device 21.

[0102] In the present embodiment, the first nozzle device 12 and the second nozzle device 16 extend approximately over 100% of the width of the construction platform 5 in the region of the gas supply side 8.

[0103] The third nozzle device 21 extends approximately over 90% of the width of the construction platform 5 in the X direction 9.

[0104] In addition, the device comprises a gas supply device 25. The gas supply device 25 is designed to supply process or functional gas and / or protective gas, such as argon or nitrogen.

[0105] The gas supply device 25 opens via a branch 27 into three lines 34, 35 and 36, which are each connected via distribution channels 26 to the first, second and third nozzle elements 13, 18 and 22.

[0106] It is provided that all first nozzle elements 13 of the first nozzle device 12, all second nozzle elements 18 of the second nozzle device 16, and all third nozzle elements 22 of the third nozzle device 21 are supplied with an identical volume flow of process or functional gas and / or protective gas via the three lines 34, 35, and 36 and the distribution channels 26. This means that the nozzle devices 12, 16, 21 and / or the three lines 34, 35, 36 and / or the branches 26 are structurally designed such that the individual nozzle elements 13, 18, 22 of the first, second, and third nozzle devices 12, 16, 21 output approximately the same volume flow.

[0107] For this purpose, first, second, and a third flow control elements 37, 38, 39 or a component for controlling the flow of gases, such as a valve or a flap, are arranged in the lines 34, 35, and 36 and / or the branches 26 in order to control the gas flow of the first, second, and third nozzle devices 12, 16, 21 such that all nozzle elements 13, 18, 22 of the nozzle devices 12, 16, 21 each output approximately the same volume flow. In the present exemplary embodiment, the flow control elements 37, 38, 39 are shown in the lines 34, 35, 36.

[0108] However, additionally and / or alternatively, flow control elements may also be arranged in the branches 26 from the lines 34, 35, 36 to the individual nozzle elements 13, 28, 22.

[0109] Furthermore, flow control elements 37, 38, 39 can be dispensed with through structural design, such as cross-sectional reductions or cross-sectional expansions of the lines 34, 35, 36 and / or the distribution channels 26. The only decisive factor is that the individual nozzle elements 13, 18, 22 of the nozzle devices 12, 16, 21 each deliver approximately the same volume flow or deliver the process or functional gas and / or protective gas at approximately the same flow velocity.

[0110] In this way, all nozzle elements together emit an approximately uniform total gas flow 33 of 2 m / s, since the nozzle elements further away from the edge region 28 are subjected to a lower volume flow of gas, but with a higher flow velocity due to a higher flow resistance in the distribution channel.

[0111] This means that all nozzle elements 13, 18, 22 emit a gas stream with a flow velocity of approximately 2 m / s.

[0112] According to this embodiment, the first, second, and third nozzle devices 12, 16, and 21 are supplied with gas from an edge region 28 of the device 1 via lines 34, 35, and 36. Supplying the nozzle devices 12, 16, and 21 from the edge region 28 enables a space-saving and compact design and, in particular, a simpler assembly of the device 1.

[0113] It is thus provided that distribution channels 26 of the lines 34, 35, 36 arranged in the edge region 28 to the nozzle elements 13, 28, 22 have a low flow resistance due to the flow control elements 37, 38, 39, which becomes increasingly greater the further the nozzle elements are spaced from the edge region 28, so that the nozzle elements are subjected to an increasingly greater flow velocity starting from the edge region 28. In this way, all nozzle elements 13, 28, 22 of the first, second and third nozzle devices 12, 16 and 21 then output approximately the same volume flow at approximately the same flow velocity. One or more flow measuring devices (not shown) are arranged in the area of ​​the build platform in the build space 2. The flow measuring device is / are designed to measure whether a laminar flow exists in the build space in the area in the Z direction slightly spaced from the build platform.

[0114] Furthermore, a control device is provided (not shown) which is connected to the flow control elements 37, 38, 39 and to the flow measuring device(s) and, on the basis of the corresponding flow values, controls the flow control elements accordingly and thus controls the volume flow from the first, second and third nozzle elements 13, 18, 22 in such a way that a laminar flow is present in the area of ​​the construction platform.

[0115] An extraction device 29 is arranged in the area of ​​the gas discharge side 11.

[0116] The suction device 29 comprises a suction nozzle 30, which extends in the Y-direction 6 approximately over 100% or the entire width of the construction platform 5. A single suction nozzle element 31 is provided for this purpose, wherein, according to the present embodiment, five suction channels 32 are formed in the suction nozzle element, which have a conically tapered cross-section.

[0117] The suction nozzle element 31 has an approximately constant cross-section in the Y direction 6.

[0118] Furthermore, according to the invention, a device 33 for additive manufacturing is provided, which comprises the device 1 described above for the directed gas exposure of a construction space 2 for additive manufacturing (not shown).

[0119] This device 33 comprises one and preferably several processing heads with pivoting arms (not shown). The processing heads and / or the pivoting arms are round in cross-section to reduce turbulence in the process chamber 3.

[0120] Preferably, the first and / or the second and / or the third nozzle device 12, 16 and 21 can be manufactured by means of an additive manufacturing process.

[0121] Furthermore, the invention also provides a method for the directed gas supply to a build space 2 for additive manufacturing with a device 1 as shown above for the directed gas supply to a build space 2, wherein a process chamber delimiting a build space has a build platform extending in a horizontal X / Y plane, and wherein a first end region of the build platform extending in the Y direction forms a gas supply side, and wherein a second end region of the build platform opposite the gas supply side in the X direction and extending in the Y direction forms a gas discharge side, and a first nozzle device which is arranged on the gas supply side immediately adjacent to the build platform and which discharges a horizontal first gas stream flowing approximately parallel to the surface of the build platform in the X direction, and a third nozzle device,which is arranged in a vertical Z-direction orthogonal to the X / Y plane above the build platform and in the X-direction horizontally offset from the first nozzle device, and is directed towards the build platform and which emits a third gas stream flowing towards the build platform, wherein the first and the third gas stream emit a total gas stream which generates a substantially laminar flow in the region of the build platform from the gas supply side towards the gas discharge side.

[0122] The device may comprise a second nozzle device which is arranged in the vertical Z-direction above the first nozzle device and below the third nozzle device and is directed towards the build platform, and which emits a second gas stream flowing towards the build platform, which is a component of the overall gas stream, and wherein the first, second and third gas streams and thus the overall gas stream generate a substantially laminar flow in the region of the build platform.

[0123] The device can comprise at least one gas supply device with a branch and distribution channels, wherein cross-sectional areas of the distribution channel are designed and / or flow control elements are provided such that all nozzle elements of the nozzle device output approximately the same volume flow of process gas.

[0124] The total gas flow and thus the gas flows of the individual flow channels of the nozzle elements can have a flow velocity between 1 m / s and 3 m / s.

[0125] The total gas flow can thus have a flow velocity of at least 1 m / s or 1.2 m / s or 1.4 m / s and a maximum of 3 m / s or 2.5 m / s and in particular of 2 m / s.

[0126] The following section discusses the results of a simulation performed using the apparatus described above.

[0127] The first part covers simulation results after geometrical improvements to the components, while the second part focuses on flow rate optimization results. The third section summarizes the simulation cases, such as the effect of a heated powder bed at 200 °C, the use of air instead of nitrogen, and the case involving obstacles such as laser arms. The simulation results demonstrate a significant improvement in the flow distribution in a process chamber of a device according to the invention or when using a method according to the invention.

[0128] Figure 5 (flow distribution on the horizontal plane at a distance of 20 mm from the powder bed after optimization) shows a velocity distribution on a horizontal plane 20 mm above the powder bed, with a fairly uniform flow distribution across the manifold and the individual nozzles. The deflection of the flow to the left of the powder bed is compensated by the extended length of the nozzles against the powder bed (Figure 5).

[0129] The liquid flow distribution in the direction perpendicular to the powder bed was plotted both as a side view of the volumetric distribution and in the center plane along the powder bed as in Figure 4 (side view of the volumetric flow distribution along the powder bed). The volumetric plot has the advantage of representing the overall flow trend with a brighter color, whereas a single plane might misrepresent the entire velocity profile along the length as a single sample. However, the single plane (Figure 4 right) better represents the interaction of the flows from the nozzles. It can be seen that the flow from the lower nozzles (first nozzle setup) is forced as it moves along the powder bed, whereas the flow from the middle and upper nozzles (second and third nozzle setup) prevents flow separation.

[0130] Furthermore, the device is able to prevent recirculation of the weld plume within the process chamber and flow over the outlet nozzle due to the shape of the outlet nozzle and the deflection by the flow from the upper nozzle. This is evident from Figures 5 and 4, as there are only areas of very low velocities in the rear area of ​​the outlet nozzle, meaning that most byproducts should be effectively captured. It can also be seen that with the help of a double plenum design in combination with a perforated plate within the nozzles and the asymmetric design of the outlet, the common problem of uneven distribution across the nozzle length can be overcome.

[0131] The upper, middle, and lower mass flow rates resulting from the surface behavior-based optimization were 0.040506 kg / s, 0.076561 kg / s, and 0.12092 kg / s, respectively. The optimization results were verified by simulation, and the results for the flow distribution 20 mm above the powder bed are shown in Figure 5. The flow uniformity in the considered horizontal and vertical planes was found to be 0.92665 and 0.89637, respectively. It can also be seen that the low-velocity region at the bottom left side of the powder bed was further improved and now covers the entire area of ​​the powder bed. This also demonstrates the importance of flow optimization in multi-inlet LPBF systems.

[0132] It can be noted that, in contrast to the velocity distribution in known devices where the flow is centered in the middle, the simulations show that the velocity does not decrease over the length of the inlet, with an average velocity of about 2.4 m / s over the entire width of the powder bed.

[0133] The velocities in the desired range are almost identical, at approximately 1.5 m / s to 2.5 m / s, which suggests a uniform flow along different sections. The lower limit of this velocity is well within the range of 1.5 m / s, which was chosen as the minimum velocity when designing the outlet nozzle.

[0134] In the simulation performed so far, the laser arms were omitted from the CAD model for simplicity. Also, due to the dynamic nature of the laser position, it would be difficult to predict the most flow-disrupting configuration of eight lasers. Since the laser arms directly impede the flow from the upper nozzles, a configuration was chosen in which the laser arms are rotated to a greater length to disrupt the flow.

[0135] It can be seen that the flow uniformity in the horizontal plane does not change significantly even after including the laser arms as in the model, since at 20 mm above the powder bed it is more strongly influenced by the flows from the lower and middle nozzles, and these two flows are unobstructed in every laser configuration. Furthermore, due to the conical cylindrical shape of the laser arms, flow separation is reduced by the Coanda effect on the curved surface of the laser arm, as shown in Figure 59.

[0136] Therefore, it can be said that the effects of the laser on the flow distribution are unlikely to be particularly pronounced, but further investigations may be necessary if the movement and rotation of the laser could cause temporary disturbances.

[0137] In the given LPBF process, the powder bed is heated to a nominal temperature of 200°C. This preheating allows the microstructure to be adjusted and the mechanical properties of the product to be improved by enhancing the thermal field generated by cyclic laser heating. Since this heating can affect fluid properties such as density and kinematic viscosity, and thus the fluid properties and related effects such as buoyancy, a simulation was conducted with a powder bed heated to 200°C. The average internal temperature of the chamber is approximately 80°C. There appears to be no significant change in the velocity distribution compared to the case without heating.

[0138] As explained in the previous sections, the simulation is validated by PIV measurements. Therefore, air is used as the liquid medium for these experiments to facilitate observations and ensure safety. The air density of 1.225 kg / m3 and the viscosity of 0.000017894 kg / ms were taken from Ansys® Fluent, 20.2. Since the fluid input was expressed as mass flow in the previous simulations, the same mass flow was assumed for three manifolds in this case to slightly compensate for the differences, although controlling the volumetric flow would be easier in an experimental setup.

[0139] The results are almost identical, and both gases have similar densities. However, due to the lower density of nitrogen, the average velocities are slightly higher, and therefore the flow rate through the exhaust nozzle is also slightly higher. Although the choice of gas plays an important role in heat dissipation, the forces on the spray particles depending on the density and chemical reactivity at high temperatures, and the quality of the LPBF fabrication, these processes are not evident in PIV measurements, so experiments with air can be considered representative of nitrogen as a fluid for flow distribution analysis.

[0140] In these experiments, the shielding gas flow system for the high-volume LPBF system was designed. The desired flow behavior was quantified in terms of average velocity, flow uniformity, and flow distribution within the chamber. The design of the shielding gas flow system was developed from scratch using the device according to the invention.

[0141] By gradually evaluating each component and its impact on flow distribution, the designs were optimized, ultimately improving flow uniformity in the final system. Simulation results show very promising flow characteristics, despite the challenges posed by the interaction of multiple nozzles and the larger volume to be covered. Among the various design concepts, the dual manifolds and perforated plates in the nozzles proved to be very influential in achieving uniform flow across the entire length. After the design was finalized, flow rates were optimized to further improve flow uniformity. Since flow homogeneity has been proven to be directly related to part quality between and within production, it can be assumed that the system can ensure consistent part properties throughout.List of reference symbols.

[0142] 1 device

[0143] 2 Installation space

[0144] 3 process chambers

[0145] 4 X / Y plane

[0146] 5 Construction platform

[0147] 6 Y-direction

[0148] 7 first end area

[0149] 8 Gas supply side

[0150] 9 X-direction

[0151] 10 second end area

[0152] 11 Gas discharge side

[0153] 12 first nozzle device

[0154] 13 first nozzle element

[0155] 14 first flow channel

[0156] 15 first gas stream

[0157] 16 second nozzle device

[0158] 17 Z-direction

[0159] 18 second nozzle element

[0160] 19 second flow channel

[0161] 20 second gas stream

[0162] 21 third nozzle device

[0163] 22 third nozzle element

[0164] 23 third flow channel

[0165] 24 third gas stream

[0166] 25 Gas supply device

[0167] 26 distribution channel

[0168] 27 Junction

[0169] 28 Marginal area

[0170] 29 Extraction device

[0171] 30 suction nozzle

[0172] 31 Suction nozzle element

[0173] 32 Suction channel

[0174] 33 Total gas flow

[0175] 34 Line

[0176] 35 Line Line first flow control element second flow control element third flow control element

Claims

Claims 1 . Device (1) for the directed gas application to a build space (2) for additive manufacturing, comprising a build space / process chamber (2, 3) with a build platform (5) extending in a horizontal X / Y plane (4), wherein a first end region (7) of the build platform (5) extending in the Y direction (6) forms a gas supply side (8), and wherein a second end region (10) of the build platform (5), opposite the gas supply side (8) in the X direction (9) and extending in the Y direction (6), forms a gas discharge side (11), a first nozzle device (12) which is arranged on the gas supply side (8) immediately adjacent to the build platform (5) and which is designed to discharge a horizontal first gas stream (15) flowing approximately parallel to the surface of the build platform (5) in the X direction (9), and a third nozzle device (21),which is arranged in a vertical Z-direction (17) orthogonal to the X / Y plane (4) above the construction platform (5) and in the X-direction (9) horizontally offset in the flow direction of the first gas flow from the first nozzle device (12), and is directed towards the construction platform (5), and which is designed to discharge a third gas flow (24) flowing in the direction of the construction platform (5), wherein the first and third nozzle devices (12, 21) are designed such that the first and third gas flows (15, 24) form a total gas flow (33) which generates a substantially laminar flow from the gas supply side (8) towards the gas discharge side (11) in the region of the construction platform (5).

2. Device (1) according to claim 1, characterized in that the device (1) has a second nozzle device (18) which is arranged in the vertical Z-direction (17) above (or above) the first nozzle device (12) and below the third nozzle device (21), and is directed in the direction of the construction platform (5), and which is designed to emit a second gas stream (20) flowing in the direction of the construction platform (5), which second gas stream is a component of the overall gas stream (33), and wherein the second nozzle device (16) is designed such that, in conjunction with the first and third nozzle devices (12, 21), the first, second and third gas streams (15, 20, 24) and thus the overall gas stream (33) generate a substantially laminar flow in the region of the construction platform (5).

3. Device (1) according to claim 1 or 2, characterized in that the first nozzle device (12) extends approximately over 70% to approximately 120% of a total width of the building platform (5) in the Y direction (6) and comprises between one and eight first nozzle elements (13), each with a flow channel, which form the first nozzle device (12), wherein at least one flow channel of the first nozzle device (12) extends approximately parallel to the building platform (5), and wherein at least one nozzle element is designed to widen conically in the X direction.

4. Device (1) according to one of claims 1 to 3, characterized in that the second nozzle device (18) extends approximately over 80% to approximately 120% of a total width of the construction platform (5) in the Y direction (6) and comprises between one and eight second nozzle elements (18), each with a flow channel, which form the second nozzle device (18), wherein at least one flow channel of the second nozzle device (18) is inclined at an acute angle of at least 5° and a maximum of 45° with respect to the construction platform (5), and wherein at least one nozzle element is designed to widen conically in the X direction.

5. Device (1) according to one of claims 1 to 4, characterized in that the third nozzle device (21) extends approximately over 40% to approximately 120% of a total width in the Y direction (6) of the building platform (5) and comprises between two and eight third nozzle elements (22) which widen conically in the Y direction (6) and each have a flow channel, which form the third nozzle device (21), wherein at least one flow channel of the third nozzle device (21) is inclined at an acute angle of at least 30° and at most 90° with respect to the building platform (5), and wherein at least one nozzle element is designed to widen conically.

6. Device (1) according to one of claims 1 to 5, characterized in that the device (1) has at least one gas supply device (25) which opens via a branch (27) into three lines (34, 35, 36), which are each connected to the first, second and third nozzle elements (13, 18, 22) via distribution channels (26), wherein flow control elements (37, 38, 39) are arranged in the three lines (34, 35, 36) and / or in the distribution channels (26) and / or wherein cross-sectional areas of the lines (34, 35, 36) of the distribution channels (26) are designed such that all nozzle elements (13, 18, 22) of the respective nozzle device (12, 16, 21) output approximately the same volume flow of process gas.

7. Device (1) according to one of claims 1 to 6, characterized in that the device (1) comprises a suction device (29) which is arranged on the gas discharge side (11) immediately adjacent to the construction platform (5) and which is designed to discharge the total gas flow (33), and which extends approximately over 50% to approximately 120% of a total width in the Y direction (6) and is preferably designed as a single suction nozzle element (31).

8. Device (1) according to one of claims 1 to 7, characterized in that the construction platform (5) extends in the X-direction (9) over a length of approximately 0.5 m to 2 m.

9. Device (1) according to one of claims 6 to 8, characterized in that the gas supply device (25) is designed such that the nozzle devices discharge the process gas at a speed of at least 1 m / s to approximately 3 m / s.

10. Device (1) for additive manufacturing comprising a device (1) for directed gas exposure of a construction space (2) according to one of claims 1 to 9, wherein Processing heads including swivel arms are round in cross-section to reduce turbulence in the process chamber.

11. Device (1) according to claim 10, characterized in that at least one nozzle device of the device (1) for the directed gas application to a construction space (2) is manufactured by means of an additive manufacturing process.

12. A method for the directed gas exposure of a build space (2) for additive manufacturing with a device (1) for the directed gas exposure of a build space (2) according to one of claims 1 to 9, wherein a build space (2) has a build platform (5) extending in a horizontal X / Y plane (4), and wherein a first end region (7) of the build platform (5) extending in the Y direction (6) forms a gas supply side (8), and wherein a second end region (10) of the build platform (5) opposite the gas supply side (8) in the X direction (9) and extending in the Y direction (6) forms a gas discharge side (11), and a first nozzle device (12) which is arranged on the gas supply side (8) immediately adjacent to the build platform (5) and which has a horizontal, approximately parallel to the surface of the build platform (5) in the X direction (9) flowing first gas stream (15), and a third nozzle device (21) which is arranged in a vertical Z direction (17) orthogonal to the X / Y plane (4) above the construction platform (5) and in the X direction (9) horizontally offset in the flow direction of the first gas flow from the first nozzle device (12), and is directed towards the construction platform (5), and which outputs a third gas flow (24) flowing in the direction of the construction platform (5), wherein the first and the third gas flow (15, 24) output a total gas flow (33) which generates a substantially laminar flow in the region of the construction platform (5) from the gas supply side (8) in the direction of the gas discharge side (11).

13. The method according to claim 12, characterized in that the device (1) has a second nozzle device (16) which is arranged in the vertical Z-direction (17) above the first nozzle device (12) and below the third nozzle device (21), and is directed towards the construction platform (5), and which emits a second gas stream (20) flowing in the direction of the construction platform (5), which is a component of the total gas stream (33), and wherein the first, the second and the third gas streams (15, 20, 24) and thus the total gas stream (33) generate a substantially laminar flow in the region of the construction platform (5).

14. The method according to claim 12 or 13, characterized in that the device (1) has at least one gas supply device (25) for supplying the nozzle devices with a gas flow, which is connected to the nozzle devices (12, 16, 21) via a branch (27) and three lines (34, 35, 36) and distribution channels (27), and wherein cross-sectional areas of the distribution channels (26) and / or the lines (34, 35, 36) are designed in such a way, and / or have flow control elements (37, 38, 39), that nozzle elements of the nozzle devices output approximately the same volume flow of process gas.

15. Method according to one of claims 12 to 14, characterized in that the total gas flow (33) has a flow velocity between 1 m / s and 3 m / s.

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