Apparatus and method for directional application of gas to molding spaces for additive manufacturing

Abstract

The invention relates to an apparatus for directed application of gas to a forming space for additive manufacturing. The invention relates to a device for forming a gas, comprising:-a process chamber defining a forming space and having a forming platform extending in an X / Y plane, a first edge region of the forming platform extending in the Y direction forming a gas supply side, and a second edge region of the forming platform opposite the gas supply side in the X direction and extending in the Y direction forming a gas discharge side; -a first nozzle device arranged on the gas supply side and directly adjacent to the forming platform and designed to output a horizontal first gas flow flowing substantially parallel to the surface of the forming platform in the X-direction; and-a third nozzle device arranged above the forming platform in a vertical Z direction perpendicular to the X / Y plane, horizontally offset towards the first nozzle device in the X direction and towards the forming platform, and designed to output a third air flow towards the forming platform, the first nozzle device and the third nozzle device are designed such that the first gas flow and the third gas flow form an overall gas flow which produces a substantially layered gas flow from the gas supply side to the gas discharge side in the region of the forming platform.

Description

TECHNICAL FIELD

[0001] The present invention relates to a device and a method for the directed application of a gas to a build space for additive manufacturing. BACKGROUND

[0002] With 3D printing, various three-dimensional components having complex geometries can be produced. The three-dimensional workpiece is built up layer by layer. The building process is controlled by a computer and is carried out from a specified size and shape (CAD) by one or more liquid or solid materials. During the building process, a physical or chemical hardening or melting process takes place. Typical materials for 3D printing are plastics, synthetic resins, ceramics, and metals.

[0003] 3D printing refers to a manufacturing process in which material is generated or added. The most important 3D printing technologies are selective laser melting (SLM) or laser powder bed fusion (LPBF) for metals, laser cladding (LA), and electron beam melting (EBM), as well as selective laser sintering (SLS) for polymers, ceramics, and metals.

[0004] In the metal processing process, the material is melted point by point or selectively, so that it is re-solidified in a different form. In such processes, metal powder or metal wire is melted and solidified layer by layer, so that three-dimensional components can be produced. Due to the locally limited laser beam energy input, the size of the formed melt pool is small. This enables the production of fine structures. The 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), etc.

[0005] In selective laser sintering (SLS / LMF), a layer of powder material is applied to the work surface (build platform). The loose powder is melted point by point or selectively by a laser beam. Depending on the material used, the powder particles can be bonded within the layer and to the underlying layer. For the production of metal components, two basic development directions can be distinguished. In addition to the direct solidification of metal powder material by means of a laser beam (direct metal laser sintering), the method of producing metal components using a combination of SLS with a plastic-coated metal powder and subsequent heat treatment (IMLS) has been established in the early stages.

[0006] Direct metal laser sintering (DMLS) uses single-component or multi-component metal materials. In particular, DMLS multi-component powders consisting of a plurality of alloying elements are used. The low-melting components contained in the powder are melted by the laser beam and flow around the high-melting components as structural building elements.

[0007] In electron beam melting (EBM), the process flow is essentially the same as for the laser-based process. Loose metal powder is melted in a powder bed or by means of a nozzle, or metal wire is melted point by point, and then solidifies into the desired contour. The energy required for this process is provided by an electron beam. The process is usually carried out in a vacuum chamber filled with an inert gas.

[0008] In electron beam melting, similar to selective laser melting (SLM), a high energy is introduced which causes the forming material to melt. This energy is not provided by a high-power laser, but by a strong electron beam, which is suitably deflected and positioned using strong magnetic coils. The electron beam melting process has to be carried out under high vacuum. This greatly limits the forming space of a device that uses selective electron beam melting.

[0009] In recent years, processes have been developed which improve the processing of single-component metal materials. Corresponding processes are commercially available, for example under the name selective laser melting (SLM).

[0010] Selective laser melting (SLM) uses a laser beam to introduce significantly more energy into the powder bed than selective laser sintering (SLS), thus producing true material melting at the corresponding location. This creates more homogeneous objects with greater density compared to the SLS process.

[0011] Laser cladding is a cladding process in which a workpiece is welded by applying and simultaneously melting almost any material. It can be carried out in powder form, such as metal powder, or with welding wire or strip. In laser cladding, a high-power laser (mainly diode lasers or fiber lasers, earlier CO2 lasers and Nd:YAG lasers) is used as a heat source. 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 supplied. At the heating point, the metal powder melts and combines with the metal of the workpiece. In addition to metal powder, ceramic powder materials can also be used, especially hard materials. Laser cladding with metal wire or strip works in a similar way to the powder process, but uses metal wire or strip as filler material.

[0012] EP 3015197 B1 describes a device for producing or repairing three-dimensional objects. The device comprises two inlet nozzles. A process gas is introduced via the inlet nozzles into the forming space or process chamber of the device. The process gas refers, inter alia, to a protective gas or an inert gas.

[0013] WO2017013454A2 discloses an apparatus for additive manufacturing and a gas flow device for use with such an apparatus. The gas flow device comprises a gas flow system to control condensate generated during a laser melting process. It comprises a first gas nozzle with a plurality of gas outlets and a gas outlet with a gas inlet. The gas outlet and the gas inlet are arranged to generate a horizontal gas flow over a working surface of a powder bed formed on a build platform. The nozzle and the outlet are believed to generate a laminar flow having a flow direction from the nozzle to the outlet.

[0014] DE112019003725T5 describes an additive manufacturing apparatus. The apparatus comprises a lower nozzle that sprays inert gas into a process chamber in a horizontal direction through a lower opening, an upper nozzle that sprays inert gas into the process chamber through an upper opening, and an inclined nozzle that sprays inert gas in an obliquely downward direction from an upper portion of a first sidewall. The inclined nozzle comprises a first nozzle having a flow path extending in a first direction from the upper portion of the first sidewall to a lower portion of a second sidewall through which the inert gas flows and is sprayed in the first direction, and a second nozzle having a flow path extending in a second direction from the upper portion of the first sidewall to an upper surface of a platform through which the inert gas flows and is sprayed in the second direction.

[0015] WO2020041438A1 discloses a system and method for flow control for an additive manufacturing system. The system comprises a lower gas supply device with a lower gas inlet with openings, and an upper gas supply device, and an upper gas inlet with openings. According to this document, laminar flow is also believed to be generated in the build platform area.

[0016] US9592636B2 relates to a laminated molding apparatus, wherein the laminated molding apparatus comprises a chamber having an inert gas supply opening and an inert gas supply space for independent smoke diffusion portions.

[0017] EP3147047A1 shows an apparatus for producing a three-dimensional workpiece, wherein the process chamber has a first gas inlet (horizontal direction) and a second gas inlet (vertical direction). The second gas inlet is approximately trapezoidal when viewed from above and has a plurality of gas inlet openings in order to supply the build platform as uniformly as possible with gas.

[0018] EP1839781B1 describes an apparatus for producing an object by building up the object layer by layer with a powdered material, wherein two protective gas supply lines are provided. The protective gas supply lines lead to a nozzle. The protective gas supply lines lead to a number of protective gas inlets.

[0019] DE 102 10 05 2 206 B4 shows a device for producing a three-dimensional object. The device has a process chamber with a protective gas injection and extraction system, wherein the protective gas is circulated in the process chamber 6.

[0020] DE 102 16 11 2 652 A1 describes a metal 3D printer working with a powder bed process. The metal 3D printer comprises a housing, a recoat head, a material supply device, a protective gas supply device, a work table and a laser irradiation device for sintering the metal powder. The protective gas supply device has a first discharge opening arranged on one side of the recoat head. Thus, the protective gas is released at the recoat head into the forming chamber, flows along the powder bed to a first outlet connection, where a suction device is provided. The recoat head can be moved over the powder bed, whereby the respective discharge opening can also be moved. In order to provide a protective or inert gas flow across the powder bed to the first suction opening, irrespective of the position of the recoat head, a second discharge opening is arranged at a fixed position in the forming chamber, so that a protective gas flow across the powder bed to the first suction opening can be generated even when the recoat head is in a distal position. The 3D printing device also has a third discharge opening on the side wall adjacent to but slightly above the other discharge openings. The protective gas, in particular nitrogen, supplied from the third discharge opening, prevents a reduction in the nitrogen concentration in the forming chamber.

[0021] DE 102 16 12 177 70 A1 shows a 3D printing device with vertically offset gas inlet elements for a protective gas, so that even multiple vertically offset gas flow layers can be created within the process chamber of a device for additive manufacturing of three-dimensional objects. According to one embodiment, the lowermost gas inlet element is inclined downwardly.

[0022] DE 102 08 03 018 6 A1 discloses another 3D printer with a process chamber for selective laser melting, which has an inlet and an outlet for a process gas, which is an inert gas, which is flowed over the surface of the component to be manufactured in order to prevent unwanted reactions of the melt pool. Furthermore, a supply system is provided, through which a reaction gas can be supplied. By adding a reaction gas, it is possible to change the composition of the component surface.

[0023] DE 102 18 21 530 1 A1 relates to a 3D printer with a gas flow device for generating a gas flow. The gas flow device is characterized in that it comprises a plurality of channels, wherein the channels have different cross sections. The channels can be used to generate a uniform or non-uniform gas flow with a turbulent flow.

[0024] It is therefore known from the prior art to provide a plurality of nozzles in a 3D printing device in order to provide the process gas as uniformly as possible to the forming platform. Furthermore, it is also known from the prior art to provide an active suction device.

[0025] Additive manufacturing processes use a powder bed, a powder feed or a wire feed, in which the raw materials are melted and then solidified with a laser beam, electron beam, plasma / electric arc. In addition, inert or active gases are used as process gases in the generation of the manufacturing process.

[0026] These processes mitigate the critical influences and conditions that arise in the process of energy input by taking appropriate measures. In this context, it is known to use a substrate on which the component is fixed, to carry out the process in a protective gas atmosphere, and to apply a new scanning strategy for the exposure of the powder to the light with the laser energy. SUMMARY

[0027] One goal of the aforementioned generation of manufacturing processes is to ensure as efficient an energy input as possible, in order to achieve a safe production process and a high-quality product component. The object of the present invention is to provide a device and a method for the targeted application of gas to a forming space for additive manufacturing, which provides an improved protective gas environment during the manufacturing process.

[0028] A further object of the present invention is to provide a device and a method for the targeted application of gas to a forming space for additive manufacturing, which ensures as efficient an energy input as possible.

[0029] A further object of the present invention is to develop a device and a method for the targeted application of gas to a forming space for additive manufacturing, which ensures a reliable manufacturing process, so that a high component quality can be achieved.

[0030] A further object of the present invention is to provide a device and a method for the targeted application of gas to a forming space for additive manufacturing, which provides an alternative to the devices and methods known from the prior art.

[0031] One or more of these objects are achieved by the features of independent claims 1, 10 and 12. Advantageous embodiments are specified in the dependent sub-claims.

[0032] The invention relates to a device for the directed application of gas to a build space for additive manufacturing. The device comprises a process chamber which defines a build space and has a build platform which extends in an X / Y plane, wherein a first edge region of the build platform which extends in the Y direction forms a gas supply side, and wherein a second edge region of the build platform which extends in the Y direction and which is opposite the gas supply side in the X direction forms a gas discharge side; a first nozzle device which is arranged on the gas supply side and directly adjacent to the build platform and which is designed to output a horizontal first gas flow which flows substantially 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 which is perpendicular to the X / Y plane, is horizontally offset in the X direction from the first nozzle device in the flow direction of the first gas flow, and is directed towards the build platform, and which is designed to output a third gas flow which flows towards the build platform, wherein the first nozzle device and the third nozzle device are designed such that the first gas flow and the third gas flow form an overall gas flow which generates a substantially laminar gas flow in the region of the build platform from the gas supply side to the gas discharge side. As a result of the first nozzle device being arranged on the gas supply side and directly adjacent to the build platform and outputting a horizontal gas flow which flows substantially parallel to the surface of the build platform in the X direction, and as a result of the third nozzle device being arranged above the build platform in a vertical Z direction which is perpendicular to the X / Y plane, being horizontally offset in the X direction from the first nozzle device, and outputting a third gas flow which flows towards the build platform, an overall gas flow is formed which generates a substantially laminar gas flow in the region of the build platform from the gas supply side to the gas discharge side.

[0033] As a result of the third nozzle device being offset in the flow direction of the first gas flow and being aligned to the build platform, the third gas flow pushes the first gas flow against the build platform. This enables the first gas flow to flow stably and laminarly in a region which is substantially larger than without the action of the third gas flow.

[0034] 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 flow.

[0035] By providing this overall gas flow which flows over the surface of the build platform and parallel to the build platform in the horizontal direction, a stable laminar flow is generated, which provides an optimum protective gas environment for the process execution, so that virtually no turbulence occurs in the region of the build platform in which the additive manufacturing is carried out. Furthermore, the gas consumption is also significantly reduced.

[0036] In this way, an effective energy input can be achieved during the production of the component.

[0037] This makes the production process safer and a high component quality can be achieved.

[0038] The device can preferably have a second nozzle device which is arranged above the first nozzle device and below the third nozzle device in the vertical Z direction and which is designed to output a second gas stream which flows towards the forming platform, the second gas stream being part of the overall gas stream, wherein the second nozzle device is designed, together with the first nozzle device and the third nozzle device, such that the first gas stream, the second gas stream and the third gas stream, i.e. the overall gas stream, generate a substantially laminar gas stream in the region of the forming platform.

[0039] By providing a second nozzle device, the aforementioned advantages with reference to the device according to the application are further optimised, since the overall gas stream flowing parallel to the forming platform is further improved in terms of avoiding turbulence and providing a stable laminar flow.

[0040] The first nozzle device can extend in the Y direction over a total width of the forming platform of approximately 70% to approximately 100%, 110% or 120% and comprise one to eight first nozzle elements, in particular structures which taper in the Y direction, each element having a flow channel, forming the first nozzle device.

[0041] Since the first nozzle device extends in the Y direction over a total width of the forming platform, gas can be applied to the forming platform continuously in the Y direction.

[0042] At least one flow channel of the first nozzle device extends approximately parallel to the forming platform.

[0043] The second nozzle device can extend in the Y direction over a total width of the forming platform of approximately 80% to approximately 100%, 110% or 120% and comprise one to eight second nozzle elements, in particular structures which taper in the Y direction, each element having a flow channel, forming the second nozzle device.

[0044] By providing several nozzle elements, the respective machining head with the rotating arm in the additive manufacturing equipment is only slightly limited in its movement within the forming space or there is sufficient space for almost free movement of the machining head.

[0045] Since the second nozzle device extends over a total width of the forming platform, a laminar gas stream can be applied to the entire surface of the forming platform.

[0046] At least one flow channel of the second nozzle device can be inclined at an acute angle of at least 5° and at most 45° with respect to the forming platform.

[0047] This arrangement of at least one flow channel of the second nozzle device supports or improves the formation of a laminar flow of the overall gas stream.

[0048] The third nozzle device can extend in the Y direction in such a way as to cover approximately 40% to approximately 100%, 110% or 120% of the total width of the forming platform and comprises two to eight third nozzle elements, in particular a structure that expands conically in the Y direction, each element having a flow channel, forming the third nozzle device. The third nozzle device also contributes to the application of a laminar flow as possible to the forming platform by the overall gas flow.

[0049] At least one flow channel of the third nozzle device can be inclined at an acute angle of at least 30° and at most 90° with respect to the forming platform.

[0050] This orientation or arrangement of the flow channels improves the laminar flow of the overall gas flow in the forming platform area.

[0051] The device can comprise at least one gas supply device which leads via a branch line to three lines which are each connected to the first nozzle element, the second nozzle element and the third nozzle element via a distribution channel, wherein flow control elements can be arranged in the three lines and / or in the distribution channel and / or the cross-sectional area of the lines of the distribution channel can be designed such that all nozzle elements of the respective nozzle device output approximately the same volume flow of process gas.

[0052] Since all nozzle elements of the respective nozzle device can obtain substantially the same volume flow of gas, the formation of the overall gas flow in the form of a laminar flow is supported or improved.

[0053] In order to design the cross-sectional area of the distribution channel accordingly, for example, nozzle elements arranged adjacent to or at a short distance from the gas supply device can be provided with a lower flow resistance, so that the respective section of the distribution channel obtains a lower flow speed.

[0054] For nozzle elements that are at a greater distance from the gas supply device, the opposite is the case. They have a higher flow resistance and thereby obtain a higher flow speed.

[0055] The measures for designing the distribution channel accordingly can be realized by a cross-sectional narrowing of the distribution channel, resistance elements and / or surface properties.

[0056] The key point is that all flow channels output the gas flow at approximately the same speed.

[0057] The device can comprise a suction device which is arranged on the gas discharge side and directly adjacent to the forming platform, designed to discharge the overall gas flow and extends in the Y direction in such a way as to cover approximately 50% to approximately 100% of the total width and is preferably designed as a single suction element.

[0058] Since the overall gas flow accordingly exits the process chamber at the gas discharge side, no additional turbulence is generated in the region of the gas discharge side and enables the overall gas flow to flow laminarly and parallel to the surface of the forming platform from the gas supply side to the gas discharge side.

[0059] The forming platform can extend in the X direction over a length of about 0.5 m to 2 m.

[0060] The forming platform can extend in the Y direction over a length of about 0.7 m to 2.5 m.

[0061] The gas supply device can be designed such that the nozzle device outputs the process gas at a speed of at least 1 m / s to about 3 m / s, preferably about 2 m / s.

[0062] It has proven advantageous for the formation of a laminar overall gas flow to have such a flow speed.

[0063] In particular, argon or nitrogen can be employed as protective gas and / or functional gas.

[0064] According to a preferred exemplary embodiment, it can be provided that the gas supply device leads via a branch line to three lines, which are respectively connected to the first nozzle device, the second nozzle device, and the third nozzle device.

[0065] 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 each obtain approximately different volume flows of the process or functional gas and / or the protective gas via the three lines, such that the individual nozzle elements of the first nozzle device, the second nozzle device, and the third nozzle device each output approximately the same volume flow.

[0066] For this purpose, a first flow control element, a second flow control element, and a third flow control element, or a means for controlling the gas flow, for example a valve or a baffle, can be arranged in the lines, in order to control the gas flow of the first nozzle elements, the second nozzle elements, and the third nozzle elements in such a way that all nozzle elements of the nozzle device each output approximately the same volume flow. In this way, all nozzle elements can jointly output an approximately uniform overall gas flow of 2 m / s, since, for example, the nozzle elements which are more remote from the edge region obtain a lower gas volume flow, but have a higher flow speed due to the higher flow resistance in the respective line.

[0067] This means that all three nozzle elements output a gas flow at a flow speed of about 2 m / s.

[0068] According to the present exemplary embodiment, the first nozzle device, the second nozzle device, and the third nozzle device can obtain the gas from the side edge region of the device via the distribution channel and the line. The supply of the nozzle devices from the edge region can achieve a space-saving and compact design, in particular a simplified assembly of the device 1.

[0069] Thus, it is provided that the nozzle elements arranged in the edge region have a lower flow resistance than in the other branch lines due to the flow control elements 37, 38, 39, so that the nozzle elements arranged in this region obtain a lower flow speed.

[0070] One or more flow measuring devices (not shown) can be arranged in the molding space in the region of the molding platform. The flow measuring devices are designed to measure whether a laminar flow exists in the molding space in the region slightly spaced apart from the molding platform in the Z direction.

[0071] Furthermore, a control device (not shown) can be provided, which is connected to the flow control elements and the flow measuring devices and controls the flow control elements accordingly on the basis of the corresponding flow values, so that the volume flow from the first nozzle element, the second nozzle element, and the third nozzle element is controlled, whereby a uniform gas flow in the form of a laminar flow exists in the region of the molding platform.

[0072] Furthermore, according to the present application, a device for additive manufacturing is provided, which has the above-described device for the targeted application of gas to the molding space, wherein the cross section of the machining head, including the rotary arm, is preferably circular in order to reduce the turbulence in the process chamber.

[0073] By providing a machining head and a rotary arm having a circular cross section, the turbulence in the process chamber is further reduced, so that the overall laminar gas flow is only slightly affected. The advantages of the additive manufacturing device according to the present application similarly correspond to the above-described advantages with reference to the device for the targeted application of gas to the molding space according to the present application.

[0074] At least one nozzle device of the device for the targeted application of gas to the molding space can be produced by means of an additive manufacturing process.

[0075] Nozzle elements or nozzle devices produced by using an additive manufacturing process can be easily and cost-effectively manufactured in an arbitrary geometry.

[0076] Furthermore, the application provides a method for the directed application of a gas to a build space for additive manufacturing, having a device for the directed application of a gas to a build space as described above, wherein: a process chamber, which delimits the build space and has a build platform extending in the 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 edge region of the build platform extending in the Y direction and opposite the gas supply side in the X 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 outputs a horizontal first gas flow flowing substantially 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 perpendicular to the X / Y plane, is horizontally offset in the X direction from the first nozzle device in the flow direction of the first gas flow, and is directed toward the build platform, and outputs a third gas flow directed toward the build platform, wherein the first gas flow and the third gas flow output an overall gas flow, which generates a generally laminar gas flow in the region of the build platform from the gas supply side to the gas discharge side.

[0077] The advantages of the method according to the application correspond analogously to the above-described advantages with reference to the device for the directed application of a gas to a build space according to the application.

[0078] The device can have a second nozzle device, which is arranged above the first nozzle device and below the third nozzle device in the vertical Z direction and is directed toward the build platform, and outputs a second gas flow directed toward the build platform, which is part of the overall gas flow, wherein the first gas flow, the second gas flow, and the third gas flow, i.e. the overall gas flow, generate a generally laminar gas flow in the region of the build platform. The device can have at least one gas supply device for supplying a gas flow to the nozzle devices, which is connected to the nozzle devices via a branch line and three lines and distribution channels, wherein the distribution channels and / or the lines are designed as cross sections and / or have flow control elements such that the nozzle elements of the nozzle devices output approximately the same volume flow of process gas.

[0079] The overall gas flow and the gas flows of the flow channels of the nozzle elements can have a flow velocity of 1 m / s to 3 m / s.

[0080] The overall gas flow can thereby have a flow velocity of at least 1 m / s, 1.2 m / s, or 1.4 m / s, and at most 3 m / s or 2.5 m / s, in particular 2 m / s. BRIEF DESCRIPTION OF DRAWINGS

[0081] The application will be described in more detail hereinafter with reference to exemplary embodiments shown in the drawings, in which: Figure 1A perspective view of a device for the targeted application of gas to a build space within a process chamber for additive manufacturing according to the present application is shown; Figure 2 A perspective view of a nozzle assembly of the device is shown; Figure 1 A side view of the device is shown; Figure 3 A perspective view of a nozzle device of the device and of a process chamber of the device is shown; Figure 4 A side view of a nozzle assembly of the device is shown; and Figure 3 A top view of a nozzle of the device is shown. Figure 5 Figure 3 DETAILED DESCRIPTION

[0082] The present application relates to a device 1 for the targeted application of gas to a build space 2 of a process chamber 3 for additive manufacturing, Figures 1 to 5 .

[0083] A build platform 5 extending in an X / Y plane 4 for additive manufacturing is arranged in the process chamber 3.

[0084] A first edge region 7 of the build platform 5 extending in a Y direction 6 forms a gas supply side 8. A second edge region 10 of the build platform 5 opposite the gas supply side 8 in an X direction 9 and extending in the Y direction 6 forms a gas discharge side 11.

[0085] Furthermore, the device comprises a first nozzle device 12. The first nozzle device 12 is arranged on the gas supply side 8 and directly adjacent to the build platform 5.

[0086] The first nozzle device 12 extends in the Y direction 6 and comprises, according to the exemplary embodiment, five first nozzle elements 13. Each nozzle element 13 is designed as a structure expanding conically in the X direction 9 and has a uniform or constant cross section in the Y direction 6.

[0087] Furthermore, each first nozzle element 13 forms a first flow channel 14 arranged substantially parallel to the surface of the build platform 5 in the X direction 9 and designed to output a flowing first gas stream 15 in the X direction 9.

[0088] The first nozzle elements 13 or their first flow channels 14 of the first nozzle device 11 are designed to output a horizontal first gas stream 15 flowing parallel to the surface of the build platform 5 in the X direction 9.

[0089] Furthermore, a second nozzle device 16 is provided, which is arranged above the first nozzle device 12 in a vertical Z direction 17.

[0090] ​​According to the present exemplary embodiment, the second nozzle device 16 comprises five second nozzle elements 18, each nozzle element 18 forming a second flow channel 19.

[0091] The second nozzle elements are designed as a structure which expands approximately conically in the X direction 9 and has an approximately constant cross section in the Y direction 6.

[0092] The second nozzle elements 18 of the second nozzle device 16 are inclined at an angle of approximately 5° with respect to the X / Y plane 14 or with respect to the forming platform, so that the second gas flow 20 is output via the second flow channels 19 and towards the forming platform 5.

[0093] Furthermore, the device comprises a third nozzle device 21 which is arranged above the forming platform 5 and the second nozzle device 16 in a vertical Z direction 17 perpendicular to the X / Y plane 4 and horizontally offset or offset in the X direction 9 from the first nozzle device 12. According to the present exemplary embodiment, the third nozzle device 21 likewise 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° with respect to the X / Y plane 4 or the forming platform; The third nozzle elements 22 are designed as a structure which expands approximately conically in the X direction 9 and has an approximately constant cross section in the Y direction 6.

[0094] The third gas flow 24 towards the forming platform 5 is output via the third nozzle elements 22 of the third nozzle device 21.

[0095] In the present exemplary embodiment, the first nozzle device 12 and the second nozzle device 16 extend in the region of the gas supply side 8 in such a way that they cover approximately 100% of the width of the forming platform 5.

[0096] The third nozzle device 21 extends in the X direction 9 in such a way that it covers approximately 90% of the width of the forming platform 5.

[0097] The device further comprises a gas supply device 25. The gas supply device 25 is designed to supply process or functional gases and / or protective gases, such as argon or nitrogen.

[0098] The gas supply device 25 opens out via branch lines 27 into three lines 34, 35 and 36, which are each connected to the first, second and third nozzle elements 13, 18 and 22 via distribution channels 26.

[0099] The setup is such 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 obtain the same volumetric flow of process or functional gas and / or shielding gas via the three lines 34, 35 and 36 and the distribution channel 26. This means that the nozzle devices 12, 16, 21 and / or the three lines 34, 35, 36 and / or the branch lines 26 are designed in such a way that the individual nozzle elements 13, 18, 22 of the first, second and third nozzle devices 12, 16, 21 output approximately the same volumetric flow.

[0100] For this purpose, first, second and third flow control elements 37, 38, 39 or means for controlling the gas flow, such as valves or flaps, are arranged in the lines 34, 35 and 36 and / or the branch lines 26, in order to control the gas flow of the first, second and third nozzle devices 12, 16, 21 in such a way that all nozzle elements 13, 18, 22 of the nozzle devices 12, 16, 21 each output approximately the same volumetric flow. In the present exemplary embodiment, the flow control elements 37, 38, 39 are shown within the lines 34, 35, 36.

[0101] However, additionally and / or alternatively, flow control elements can also be arranged in the branch lines 26 from the lines 34, 35, 36 to the individual nozzle elements 13, 28, 22.

[0102] Due to structural configurations, such as a constriction or expansion of the cross section of the lines 34, 35, 36 and / or the distribution channel 26, flow control elements 37, 38, 39 can also be omitted. The only decisive factor is that the individual nozzle elements 13, 18, 22 of the nozzle devices 12, 16, 21 each output approximately the same volumetric flow or process or functional gas and / or shielding gas at approximately the same flow rate.

[0103] In this way, all nozzle elements together output an approximately uniform total gas flow 33 of 2 m / s, since the nozzle elements further away from the edge region 28 obtain a lower gas volumetric flow, but have a higher flow rate due to the higher flow resistance in the distribution channel.

[0104] This means that all nozzle elements 13, 18, 22 output a gas flow at a flow rate of approximately 2 m / s.

[0105] According to the present exemplary embodiment, the first, second and third nozzle devices 12, 16 and 21 obtain gas from the edge region 28 of the device 1 via the lines 34, 35, 36. Supplying the nozzle devices 12, 16 and 21 from the edge region makes it possible to achieve a space-saving and compact design, in particular to simplify the assembly process of the device 1.

[0106] Therefore, the arrangement is such that the dispensing channels 26 from the lines 34, 35, 36 to the nozzle elements 13, 28, 22 arranged in the edge region 28 have a low flow resistance due to the flow control elements 37, 38, 39, and this resistance increases gradually with increasing distance of the nozzle elements from the edge region 28, so that the nozzle elements obtain a gradually increasing flow rate 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 output a substantially equal volume flow at a substantially equal flow rate. One or more flow measuring devices (not shown) are arranged in the region of the forming platform in the forming space 2. The flow measuring devices are designed to measure whether a laminar flow exists in the forming space in the region spaced slightly from the forming platform in the Z direction.

[0107] Furthermore, a control device (not shown) is provided, which is connected to the flow control elements 37, 38, 39 and the flow measuring devices and controls the flow control elements accordingly on the basis of the corresponding flow values, so that the volume flow from the first, second and third nozzle elements 13, 18, 22 is controlled, whereby a uniform gas flow in the form of a laminar flow exists in the region of the forming platform.

[0108] The suction device 29 is arranged in the region of the gas discharge side 11.

[0109] The suction device 29 comprises a suction nozzle 30, which extends in the Y direction 6 in such a way that it covers approximately 100% or the entire width of the forming platform. For this purpose, a single suction nozzle element 31 is provided, in which five suction channels 32 are formed, which have a conical cross section, in the suction nozzle element according to the present exemplary embodiment.

[0110] The suction nozzle element 31 has a substantially constant cross section in the Y direction 6.

[0111] Furthermore, according to the present application, a device 33 for additive manufacturing is provided, which comprises the above-described device 1 (not shown) for the directed application of gas to the forming space 2 for additive manufacturing.

[0112] The device 33 comprises one and preferably a plurality of machining heads with a rotary arm (not shown). The machining heads and / or the rotary arm have a circular cross section in order to reduce the turbulence in the process chamber 3.

[0113] Preferably, the first and / or the second and / or the third nozzle device 12, 16 and 21 can be produced by means of an additive manufacturing process.

[0114] Further, the invention provides a method for the directed application of gas to a build space 2 for additive manufacturing, with a device 1 for the directed application of gas to a build space 2 as described above, wherein: a process chamber, which defines the build space and has a build platform extending in the 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 edge region of the build platform extending in the Y direction opposite the gas supply side in the X direction forms a gas discharge side; a first nozzle arrangement arranged on the gas supply side directly adjacent to the build platform and outputs a horizontal first gas flow in the X direction substantially parallel to the surface of the build platform; and a third nozzle arrangement arranged above the build platform in a vertical Z direction perpendicular to the X / Y plane, horizontally offset in the X direction to the first nozzle arrangement, and towards the build platform, and outputs a third gas flow towards the build platform, wherein the first gas flow and the third gas flow output an overall gas flow which generates a generally laminar gas flow in the region of the build platform from the gas supply side to the gas discharge side.

[0115] The device can have a second nozzle arrangement arranged above the first nozzle arrangement and below the third nozzle arrangement in the vertical Z direction and towards the build platform, and outputs a second gas flow towards the build platform, which is part of the overall gas flow, wherein the first gas flow, the second gas flow, and the third gas flow, i.e. the overall gas flow, generate a generally laminar gas flow in the region of the build platform.

[0116] The device can comprise at least one gas supply device having a branch line and a distribution channel, wherein the distribution channel is designed in cross section and / or provided with a flow control element such that all nozzle elements of the nozzle arrangement output approximately the same volume flow of process gas.

[0117] The overall gas flow and the gas flow of the respective flow channel of the nozzle elements can have a flow velocity of 1 m / s to 3 m / s.

[0118] The overall gas flow can thereby have a flow velocity of at least 1 m / s, 1.2 m / s or 1.4 m / s, and at most 3 m / s or 2.5 m / s, in particular 2 m / s.

[0119] The following sections discuss the results of simulations using the above-described device.

[0120] The first section relates to simulation results after optimization of the geometry of the component, the second section relates to optimization results for the flow velocity. The third section summarizes simulation scenarios, for example, the effect of heating the powder bed at 200°C, the use of air instead of nitrogen, and scenarios including obstacles such as a laser arm. The simulation results show that the flow distribution is significantly improved in the process chamber of a device according to the invention, or when using a device or a method according to the invention.

[0121] Figure 5 The velocity profile at the horizontal plane 20 mm above the powder bed, by means of the distributor and the individual nozzles, shows a rather uniform distribution of the gas flow. The deflection of the gas flow towards the left side of the powder bed is compensated by the extension of the nozzles towards the powder bed (left side Figure 5 ).

[0122] The fluid distribution perpendicular to the direction of the powder bed is shown both as a side view of the volume flow distribution and as a single plane along the middle of the powder bed, as shown in Figure 4 (left side volume flow distribution of the powder bed). The advantage of the volume representation is that the overall flow trend can be presented with brighter colors, while a single plane can falsely represent the overall velocity distribution as a single sample. However, the single plane (right side Figure 4 ) better represents the interaction of the gas flows from the nozzles. It can be seen that the gas flow from the lower nozzles (first nozzle arrangement) is subjected to pressure as it moves along the powder bed, while the gas flows from the middle and upper nozzles (second and third nozzle arrangements) prevent the above-mentioned flow separation.

[0123] In addition, due to the shape of the outlet nozzles and the deflection of the gas flow from the upper nozzles, the device is able to prevent the re-circulation of the gas flow through the outlet nozzles and the welding rod inside the process chamber. It can be seen from Figure 5 and Figure 4 that due to the very low velocity area only at the rear area of the outlet nozzles, it means that most of the by-products should be effectively captured. It can also be seen that the common problem of uneven nozzle length distribution is overcome with the help of the double plenum design, combined with the perforated plate inside the nozzles and the asymmetric design of the outlet.

[0124] The optimized upper, middle and lower layer mass flow based on the surface behavior optimization are 0.040506 kg / s, 0.076561 kg / s, and 0.12092 kg / s, respectively. The optimized results are verified by simulation, and the flow distribution 20 mm above the powder bed is shown in Figure 5 . The flow uniformity in the horizontal and vertical planes is determined to be 0.92665 and 0.89637, respectively. It can also be seen that the low velocity area at the lower left side of the powder bed is further improved and now is able to cover the entire area of the powder bed. This also demonstrates the importance of flow optimization in a multi-inlet LPBF system.

[0125] It can be noted that compared to the velocity distribution in the existing device where the gas flow is concentrated in the middle, the simulation shows that the velocity does not decrease over the length of the inlet, with an average velocity of about 2.4 m / s over the overall width of the powder bed.

[0126] The velocities are almost identical in the desired range, from about 1.5 m / s to 2.5 m / s, which indicates that the airflow is uniform along the different sections. The lower limit of this velocity is explicitly close to 1.5 m / s, which was chosen as the minimum velocity when designing the outlet nozzles.

[0127] In the simulations performed so far, the laser arms were omitted from the CAD model for simplicity, and it was also difficult to predict the maximum perturbation configuration of the eight lasers due to the dynamic nature of the laser position. Since the laser arms directly obstruct the airflow from the upper nozzles, a configuration was chosen in which the laser arms were rotated to have a greater length to disturb the airflow.

[0128] It can be seen that the flow uniformity in the horizontal plane does not change significantly even after including the laser arms in the model, since at 20 mm above the powder bed it is mainly affected by the airflow from the lower and middle nozzles, which are not affected by the obstacles in any laser configuration. Moreover, due to the conical cylindrical shape of the laser arms, the Coanda effect of the curved surface of the laser arms should reduce the airflow separation, as shown in Figure 59.

[0129] Therefore, it can be said that the influence of the lasers on the flow distribution is unlikely to be particularly significant, but further research can be required if the movement and rotation of the lasers can cause transient disturbances.

[0130] In the given LPBF process, the powder bed is heated to a nominal temperature of 200 °C. This preheating allows the microstructure to be regulated by intensifying the thermal field generated by the circulating laser and improves the mechanical properties of the product. Since this heating affects the fluid properties, such as density and kinematic viscosity, which in turn affect the fluid properties and related consequences, such as buoyancy, simulations were performed with a powder bed heated to 200 °C. The average temperature inside the chamber was about 80 °C. The velocity distribution does not seem to change significantly compared to the unheated case.

[0131] As mentioned in the previous section, the simulations were validated by PIV measurements. Therefore, air was used as the fluid medium for these experiments to facilitate observation and ensure safety. The air density is 1.225 kg / m 3 , and the viscosity is 0.000017894 kg / ms, taken from Ansys® Fluent, 20.2. Since in previous simulations the fluid inputs were all expressed in mass flow, in this case the same mass flow was set for the three distributors to slightly compensate for the differences, although in the experimental setup the control of the volume flow would be easier.

[0132] The results were almost identical, with both gases having similar densities. However, due to the lower density of nitrogen, its average velocity was slightly higher, and thus the flow rate through the exit nozzle was also slightly higher. While the choice of gas plays an important role in heat dissipation, density-dependent forces on the ejected particles, high-temperature chemical reactivity, and the quality of the LPBF production, these processes were not evident in the PIV measurements, and thus the experiments with air can be considered as analogous to the flow rate distribution analysis with nitrogen as the fluid.

[0133] In these experiments, a shielding gas flow system was designed for a volume LPBF system. The required flow behavior was quantified in terms of average velocity, flow uniformity, and flow distribution in the chamber. The design of the shielding gas flow system was entirely new and developed using the device according to the invention.

[0134] By evaluating the individual components and their influence on the flow distribution in stages, the design was optimized, ultimately improving the flow uniformity in the final system. Despite the challenges posed by the interaction of multiple nozzles and the larger volume to be covered, the simulation results show very promising flow characteristics. Among the various design concepts, the double distributor and the perforated plate in the nozzle proved to have a significant influence on the uniform flow over the entire length. After the design was completed, the flow rate was optimized to further improve the flow uniformity. Since it has been proven that the flow uniformity is directly related to the quality of the components between and during production, it can be assumed that the system ensures consistency in the properties of the components everywhere.

[0135] List of reference signs 1. device 2. shaping space 3. process chamber 4. X / Y plane 5. shaping platform 6. Y direction 7. first edge region 8. gas supply side 9. X direction 10. second edge region 11. gas discharge side 12. first nozzle device 13. first nozzle element 14. first flow channel 15. first gas flow 16. second nozzle device 17. Z direction 18. second nozzle element 19. second flow channel 20. second gas flow 21. third nozzle device 22. third nozzle element 23. third flow passage 24. third gas flow 25. gas supply 26. distribution passage 27. branch line 28. edge region 29. suction device 30. suction mouth 31. suction mouth element 32. suction passage 33. overall gas flow 34. line 35. line 36. line 37. first flow control element 38. second flow control element 39. third flow control element

Claims

1. An apparatus (1) for directional application of gas to a forming space (2) in additive manufacturing, comprising: A molding space / process chamber (2, 3) has a molding platform (5) extending in a horizontal X / Y plane (4), wherein a first edge region (7) of the molding platform (5) extending in the Y direction (6) forms a gas supply side (8), and wherein a second edge region (10) of the molding platform (5) opposite to the gas supply side (8) in the X direction (9) and extending in the Y direction (6) forms a gas discharge side (11). The first nozzle device (12) is arranged on the gas supply side (8) and directly adjacent to the forming platform (5), and is designed to output a horizontal first airflow (15) in the X direction (9) that is substantially parallel to the surface flow of the forming platform (5). The third nozzle device (21) is arranged above the forming platform (5) in the vertical Z direction (17) perpendicular to the X / Y plane (4), horizontally offset towards the first nozzle device (12) in the X direction (9) along the flow direction of the first airflow, and facing the forming platform (5), and is designed to output a third airflow (24) flowing towards the forming platform (5). The first nozzle device and the third nozzle device (12, 21) are designed such that the first airflow and the third airflow (15, 24) form a total airflow (33), which generates a generally stratified airflow from the gas supply side (8) to the gas discharge side (11) in the region of the forming platform (5).

2. The apparatus (1) according to claim 1, characterized in that, The device (1) has a second nozzle device (18) which is arranged above the first nozzle device (12) and below the third nozzle device (21) in the vertical Z direction (17) and faces the forming platform (5), and is designed to output a second airflow (20) flowing toward the forming platform (5), the second airflow (20) being part of the overall airflow (33), wherein the second nozzle device (16) is designed together with the first nozzle device (12) and the third nozzle device (21) such that the first airflow, the second airflow, and the third airflow (15, 20, 24), i.e. the overall airflow (33), generate a generally stratified airflow in the region of the forming platform (5).

3. The apparatus (1) according to claim 1 or 2, characterized in that, The first nozzle device (12) extends in the Y direction (6) in such a way that it covers about 70% to about 120% of the total width of the molding platform (5) and includes one to eight first nozzle elements (13), each having a flow channel to form the first nozzle device, wherein at least one flow channel of the first nozzle device (12) extends in a manner generally parallel to the molding platform (5), and wherein at least one nozzle element is designed to have a structure that extends in a tapered manner in the X direction.

4. The apparatus (1) according to any one of claims 1 to 3, characterized in that, The second nozzle device (18) extends in the Y direction (6) in such a way that it covers about 80% to about 120% of the total width of the forming platform (5), and includes one to eight second nozzle elements (18), each element having a flow channel forming 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 at most 45° relative to the forming platform (5), and wherein at least one nozzle element is designed to have a structure that extends in a tapered manner in the X direction.

5. The apparatus (1) according to any one of claims 1 to 4, characterized in that, The third nozzle device (21) extends in the Y direction (6) in such a way that it covers about 40% to about 120% of the total width of the forming platform (5), and includes two to eight third nozzle elements (22) that extend in a tapered manner in the Y direction (6), each element having a flow channel forming 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° relative to the forming platform (5), and wherein at least one nozzle element is designed to extend in a tapered manner.

6. The apparatus (1) according to any one of claims 1 to 5, characterized in that, The apparatus (1) has at least one gas supply device (25) which is connected via a branch line (27) to three pipelines (34, 35, 36), which are respectively connected via a distribution channel (26) to a first nozzle element, a second nozzle element, and a third nozzle element (13, 18, 22), wherein flow control elements (37, 38, 39) are arranged in the three pipelines (34, 35, 36) and / or in the distribution channel (26), and / or the cross-sectional area of ​​the pipelines (34, 35, 36) of the distribution channel (26) is designed such that all nozzle elements (13, 18, 22) of each nozzle device (12, 16, 21) output process gas at approximately the same volumetric flow rate.

7. The apparatus (1) according to any one of claims 1 to 6, characterized in that, The device (1) includes a suction device (29) arranged on the gas exhaust side (11) and directly adjacent to the forming platform (5), designed to exhaust the overall airflow (33) and extend in the Y direction (6) in such a way that it covers about 50% to about 120% of the total width, and preferably designed as a single suction element (31).

8. The apparatus (1) according to any one of claims 1 to 7, characterized in that, The forming platform (5) extends in the X direction (9) for a length of approximately 0.5 m to 2 m.

9. The apparatus (1) according to any one of claims 6 to 8, characterized in that, The gas supply device (25) is designed to output process gas at a speed of at least 1 m / s to about 3 m / s.

10. An apparatus (1) for additive manufacturing, comprising means (1) for directionally applying gas to a forming space (2) according to any one of claims 1 to 9, wherein, The machining head, including the rotating arm, has a circular cross-section to reduce turbulence in the process chamber.

11. The apparatus (1) according to claim 10, characterized in that, At least one nozzle device of the apparatus (1) for directional application of gas to the forming space (2) is produced by an additive manufacturing process.

12. A method for directionally applying gas to a forming space (2) for additive manufacturing, the method comprising an apparatus (1) for directionally applying gas to a forming space (2) according to any one of claims 1 to 9, wherein: The molding space (2) has a molding platform (5) extending in the X / Y plane (4), wherein a first edge region (7) of the molding platform (5) extending in the Y direction (6) forms a gas supply side (8), and wherein a second edge region (10) of the molding platform (5) opposite to 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) is arranged on the gas supply side (8) and directly adjacent to the forming platform (5), and outputs a horizontal first airflow (15) in the X direction (9) that is substantially parallel to the surface flow of the forming platform (5); and The third nozzle device (21) is arranged above the forming platform (5) in the vertical Z direction (17) perpendicular to the X / Y plane (4), horizontally offset towards the first nozzle device (12) in the X direction (9) along the flow direction of the first airflow, and towards the forming platform (5), and outputs a third airflow (24) flowing towards the forming platform (5), wherein the first airflow and the third airflow (15, 24) output a total airflow (33), which generates a generally stratified airflow from the gas supply side (8) to the gas discharge side (11) in the region of the forming platform (5).

13. The method according to claim 12, characterized in that, The device (1) has a second nozzle device (16) which is arranged above the first nozzle device (12) and below the third nozzle device (21) in the vertical Z direction (17) and faces the forming platform (5), and outputs a second airflow (20) flowing toward the forming platform (5). The second airflow (20) is part of the overall airflow (33), wherein the first airflow, the second airflow, and the third airflow (15, 20, 24), i.e. the overall airflow (33), generate a generally stratified airflow in the region of the forming platform (5).

14. The method according to claim 12 or 13, characterized in that, The apparatus (1) has at least one gas supply device (25) for supplying gas flow to the nozzle device, the gas supply device (25) being connected to the nozzle device (12, 16, 21) via a branch line (27) and three pipelines (34, 35, 36) and a distribution channel (27), wherein the cross-section of the distribution channel (26) and / or the pipelines (34, 35, 36) is designed to and / or have flow control elements (37, 38, 39) such that the nozzle elements of the nozzle device output process gas at approximately the same volumetric flow rate.

15. The method according to any one of claims 12 to 14, characterized in that, The overall airflow (33) has a velocity of 1 m / s to 3 m / s.

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