Machine tool and flow-guiding device

Abstract

The invention relates to a machine tool (100) for the layer-by-layer additive construction of workpieces, which comprises a process chamber (10) in which the additive construction of workpieces takes place, a process gas device (40) which is designed to introduce a process gas stream (41) into the process chamber (10) during the additive construction, and a flow-guiding element (51) for the process gas stream (41), which is fastened within the process chamber (10) and is able to be deformed in a resilient manner between a first position, in which the flow-guiding element (51) has a first external contour geometry, and a second position, in which the flow-guiding element (51) has a second outer contour geometry differing from the first.

Description

Machine tool and flow guide device DESCRIPTION Technical field

[0001] The present invention relates to a machine tool for the layer-by-layer additive manufacturing of workpieces and a flow guide device for use in a machine tool. Background of the invention

[0002] Prior art has revealed primary forming processes for the additive manufacturing of three-dimensional workpieces, in the course of which a workpiece is built up layer by layer from a provided material.

[0003] For this purpose, a powdered material is usually applied as a material layer to a carrier located in a process chamber of a machine tool and then solidified into a workpiece layer by site-specific irradiation, for example by melting or sintering the individual material particles of the material layer.

[0004] Once a workpiece layer has solidified, a new layer of unprocessed material is applied to the substrate or to the already produced workpiece layer, and the workpiece is irradiated again at the specific location.

[0005] In this way, the workpiece is successively built up layer by layer from material of a large number of material layers applied to the substrate.

[0006] During this manufacturing process, undesirable effects typically occur, which negatively impact the process conditions within the process chamber and ultimately also negatively affect the manufacturing quality.

[0007] The process chamber, defined by its boundaries, is thus subjected to contamination, for example, from exhaust gases generated during solidification or from the stirring up of unsolidified material. Furthermore, the process chamber is gradually heated by the waste heat generated during irradiation, which can lead, for example, to thermally induced deformations of individual components within the process chamber.

[0008] To counteract these negative effects and to provide largely unchanged and optimal process conditions during the manufacturing process, a process gas stream is usually passed through the process chamber, via which, for example, the aforementioned impurities or the waste heat generated are removed from the process chamber.

[0009] However, the process gas flow itself can be a source of undesirable effects, such as stirring up the unsolidified material on the carrier, which not only contaminates the process space itself but also leads to inhomogeneity in the applied material.

[0010] To counteract this, the process gas flow and process chamber are coordinated to ensure, for example, a laminar process gas flow without turbulence. This coordination is made more difficult by other machine tool components located in the process chamber, such as a movable coater for applying the material to the substrate, which can cause undesirable turbulence.

[0011] From EP 3 928 900 A1, a machine tool with a movable coater is known in which a process chamber is essentially cuboid in shape, with flat side walls running parallel to the direction in which a process gas stream is introduced into the process chamber, so that the process gas stream can flow essentially along the flat elements without turbulence. In order to eliminate the coater, which is movable within the process chamber, as a source of undesirable turbulence, it is moved out of the process chamber through an opening in a side wall, which can be closed by a flap, after material has been applied to the bottom support.

[0012] Such a solution requires a design for the entire process chamber specifically tailored to the process gas flow, with essentially planar boundary surfaces to guide the gas flow. This significantly restricts the designers' scope for customization and makes it virtually impossible to retrofit additional components within the process chamber, as these would disrupt the gas flow. Examples of such components include an optical system for monitoring the manufacturing process, lighting elements, or other sensors / actuators for monitoring and controlling the manufacturing process. Summary of the invention

[0013] One object of the present invention is therefore to provide an efficient means of selectively guiding a process gas flow through a process chamber of a machine tool set up for additive manufacturing, which is easily adaptable to changing configurations of the machine tool.

[0014] To solve this problem, a machine tool according to claim 1 and a flow guide device according to claim 20 are provided.

[0015] The respective dependent claims relate to preferred embodiments, which can each be provided individually or in combination.

[0016] According to a first aspect of the invention, a machine tool for the layer-by-layer additive manufacturing of workpieces is provided, comprising a process chamber in which the additive manufacturing of workpieces takes place, a process gas device which is configured to introduce a process gas flow into the process chamber during the additive manufacturing process, and a flow guide element for the process gas flow fixed within the process chamber, which is elastically deformable between a first position in which the flow guide element has a first outer contour geometry, and a second position in which the flow guide element has a second outer contour geometry that differs from the first.

[0017] The flow guide element serves to direct the process gas flow introduced at an inlet through the process chamber to an outlet, ideally in the form of a laminar flow without turbulence of the process gas flow or the like.

[0018] One or more sections of an outer contour of the flow guide element form, at least in the first position of the flow guide element, one or more flow interfaces for the process gas stream flowing through the process chamber, which is guided from an inlet into the process chamber along the flow interface to the outlet. The outer contour geometry refers to the geometry of said outer contour.

[0019] Other flow interfaces can be formed by side / ceiling or bottom elements of the process chamber.

[0020] The flow guide element attached inside the process chamber thus introduces a flow boundary surface for the process gas flow that differs from the inner contour of the process chamber, as a result of which said process gas flow can be directed through a specific area of ​​the process space (interior of the process chamber) defined by the process chamber.

[0021] This allows geometries, elements or components of the machine tool in the process area that would otherwise lead to disturbances in the process gas flow to be shielded from the process gas flow via the flow guide element.

[0022] The elastic deformability of the flow guide element according to the invention, whose outer contour can thereby be transformed between the first outer contour geometry and the second outer contour geometry, allows the flow guide element to be adapted to changing boundary conditions in the process area, so that the process gas flow can always be optimally guided through the process chamber. As an example of said changing Boundary conditions are components of the machine tool that move (i.e., are moving) during the manufacturing process.

[0023] The magnitude of the deformation between the first and second positions is noticeably perceptible, such that it can be greater than 2%, preferably greater than 5% and even more preferably greater than 20%, for example, with respect to the length or width of the section of the flow guide element acting as a flow interface.

[0024] In a preferred embodiment, the flow-guiding element is designed such that the first outer contour geometry essentially corresponds to a flat surface.

[0025] In this way, a particularly simple geometry is provided for guiding the process gas flow, which, compared to an arbitrarily curved surface, does not lead to any turbulence.

[0026] In a preferred embodiment, the flow guide element is arranged in the first position such that the flat surface runs parallel to an inlet direction of the introduced process gas flow.

[0027] Parallel here is to be understood as meaning that a direction vector of the introductory direction runs orthogonally to a normal vector of the plane surface.

[0028] In this way, the flow guide element is subjected to shear only by the parallel inflowing process gas stream (caused by shear stresses in the fluid, i.e., in the process gas stream), which, in contrast to an otherwise angularly impacting process gas stream coming from the inlet, means a lower load for the flow guide element.

[0029] Alternatively, the flow guide element can also be designed in such a way that the flat surface is perpendicular to the direction of introduction. In this case, the flow guide element can even be used as a diverting element to correct the direction of the introduced process gas flow, for example to compensate for assembly-related inaccuracies, especially of the inlet.

[0030] The first position should not be limited to a parallel arrangement, but can also be arranged at an angle to the direction of introduction such that the normal vector and the direction vector of the direction of introduction are at an angle of 30 degrees to less than 90 degrees, preferably of 45 degrees to less than 90 degrees and particularly preferably of 70 degrees to less than 90 degrees to each other.

[0031] Preferably, said angle is adjustable via an adjustable bearing device by which the flow guide element is attached in the process chamber.

[0032] In particular, the storage device is attached to a ceiling element of the process chamber and comprises a mounting element for mounting on the ceiling element and a [missing word] with this connected and angularly adjustable retaining element relative to the mounting element, to which the flow guide element is attached

[0033] Preferably, guide devices can be provided on side elements of the process chamber in which one or more end sections of the flow guide element are guided, in particular in such a way that these are guided to be displaceable translationally in a displacement direction.

[0034] This provides additional support for the flow guide element, resulting in a more stable attachment within the process chamber, which also does not hinder or block any optionally foreseen movement of the flow guide element.

[0035] In a preferred embodiment, the flow-guiding element is a flexible surface element.

[0036] A surface element is an element whose geometric dimensions are defined in a The thickness direction (thickness) is preferably smaller than the dimensions in a width and a length direction (width and length).

[0037] Preferably, it is a thin surface element in which the ratio of thickness to width or thickness to length is less than or equal to 10%, preferably less than 5%, more preferably less than 1% and particularly preferably less than 0.1%.

[0038] Flexibility in this context means that the bending stiffness for bending deformations of the surface element in the thickness direction is smaller than the tensile stiffness in the longitudinal or width direction.

[0039] For the purpose of comparing bending and tensile stiffnesses with regard to the different SI units, the bending stiffness can be understood as the stiffness of the surface element, which describes the restoring force that counteracts a single force acting in the thickness direction at a reference point of the surface element. The reference point is preferably placed in a central area and not in an edge area of ​​the surface element in order to obtain a suitable reference value for the bending stiffness.

[0040] Preferably, the ratio of the bending stiffness to the tensile stiffness in the longitudinal or in the width direction of the surface element is less than 25%, preferably less than 10%, more preferably less than 5% and particularly preferably less than 1%.

[0041] Due to its design as a flexible surface element, the flow guide element can be deformed particularly easily and without much effort, which is especially beneficial for deformation from the first to the second position (or vice versa). On the other hand, the stiffnesses parallel to the surface acting as the flow interface are very high, so that shear distortions due to the process gas flow are very low.

[0042] Accordingly, the flow guide element is preferably deformable by bending deformation between the first and second positions.

[0043] In a preferred embodiment, the flexible surface element is a foil element or a fabric element.

[0044] In this way, the flow guide element can be manufactured particularly cost-effectively.

[0045] The foil element can be a metallic foil or a plastic foil. The fabric element can consist of a woven or knitted fabric, for example, made of textile, plastic, carbon, or metal fibers.

[0046] The sheet metal element can be a thin sheet, for example made of an aluminum or steel alloy, especially a spring steel strip. This allows for the provision of a particularly resistant flow guide element.

[0047] In a preferred embodiment, the flow guide element in the first position divides an interior of the process chamber into a first area and a second area, wherein the first area is a process area in which the additive assembly takes place, and wherein the process gas device is configured to introduce the process gas flow into the first area.

[0048] This method allows for a particularly simple subdivision of the process chamber, enabling the process area to be geometrically optimized for the process gas flow, regardless of the chamber's size. Furthermore, this provides a separate area within the process chamber where machine tool components can be located that would otherwise negatively impact the process gas flow (i.e., without subdivision). These components could include, for example, additional sensor devices or a filling device for the layered application of material.

[0049] If the flow guide element is designed as a foil element, it is preferably transparent (or semi-transparent) so that an optical beam can pass through it (mostly) unimpeded. This allows, for example, a machine operator to see through the flow guide element into the first area (process area) in order to monitor the manufacturing process there.

[0050] In a preferred embodiment, a construction area of ​​the machine tool, on which the layer-by-layer construction takes place, is arranged entirely in the first area.

[0051] This means that almost all sources of contaminants (suspended material, exhaust gases, combustion products) are located in the area through which the process gas flows, allowing them to be reliably carried away by the process gas flow. Furthermore Components of the machine tool located in the other area are shielded from said contaminants.

[0052] In a preferred embodiment, the process chamber comprises lateral housing elements, a top-side housing element and a bottom-side housing element, wherein the housing elements and the flow guide element are arranged relative to each other such that in the first position of the flow guide element, the introduced process gas flow flows as a parallel flow along the flow guide element through the first region of the interior of the process chamber.

[0053] This minimizes potential sources of turbulence in the first area of ​​the interior, resulting in a particularly stable flow condition. In this way, any turbulence or eddies that do occur dissipate relatively quickly.

[0054] In a preferred embodiment, the machine tool comprises a recoater movable relative to the process chamber between a first and a second end position, which is configured to apply material layers for additive manufacturing to a build area of ​​the machine tool in the process chamber, and is further configured to elastically deform the flow guide element by means of a movement between the first position and the second position.

[0055] The coater, typically used for applying material layers, can thus be employed as a component of the machine tool that can move relative to the build area within the process chamber, without obstructing the process gas flow in its end positions. The flow guide element functions as a variable or passively adjustable partition within the process chamber, with the adjustment movement being initiated by the coater. This allows the coater to move through the first section of the process chamber without the need for complex, independently driven partitions to grant it access to and from this first section.

[0056] In this way, the coater can reversibly displace the flow guide element during its traversing movement in order to reach, for example, an end position outside the first area, without the flow guide element itself having to be moved by a drive or the like.

[0057] In a preferred embodiment, the flow guide element is moved into the second position when the coater is in its first end position, wherein the flow guide element at least partially rests against the coater, and in particular partially conforms to its outer contour.

[0058] In this way, the coater and flow guide element close flush with each other in the second position, so that the first and second areas within the process chamber are relatively tightly separated from each other even in the second position.

[0059] In a preferred embodiment, a side surface of the coater forms a guide surface for the introduced process gas flow in the first end position.

[0060] This means that the coater itself acts as a kind of flow guide element for the process gas flow, which, among other things, saves on additional materials for guide elements that would otherwise have to be provided separately.

[0061] In a preferred embodiment, the side surface of the coater in the first end position and an outer contour of the flow guide element in the first position lie in the same plane relative to the process chamber.

[0062] In this way, the coater partially assumes the position of the flow guide element in the first end position, so that the flow boundary surface for the process gas flow in the first position of the flow guide element geometrically corresponds to the flow boundary surface for the process gas flow when the coater is in the first end position. The geometric boundary conditions for the process gas flow therefore remain largely unchanged for the two configurations mentioned, so that no different influences on the process gas flow are to be expected in the two cases.

[0063] In a preferred embodiment, a restoring weight is attached to the flow guide element such that its weight force acts as a restoring force to return the flow guide element to the first position.

[0064] In this way, a reset mechanism can be provided particularly easily and cost-effectively, which quickly returns the flow guide element to its first position, for example, if the coater moves out of the first end position and thereby loses contact with the flow guide element.

[0065] In addition, the restoring weight stabilizes the flow guide element when it is subjected to the process gas flow, thereby reducing and, in particular, completely suppressing vibrations of the same.

[0066] In a preferred embodiment, the flow guide element is designed as part of a flow guide device of the machine tool, which, in addition to the flow guide element, includes at least one further flow guide element for the process gas flow.

[0067] In this way, a flow guidance device comprising multiple flow guidance elements is provided in the machine tool, via which the interior of the The process chamber can be optimally adapted to the process gas flow in several areas and / or sections.

[0068] The additional flow-guiding element(s) are preferably designed in the same manner as the "first" flow-guiding element, in particular as flexible surface elements, preferably designed as foil elements, fabric elements, or sheet metal elements. The use of restoring weights is also suitable here.

[0069] In a preferred embodiment, the further flow guide element is arranged parallel to the flow guide element in the first position, whereby this should not be understood as a restriction of the orientation.

[0070] Other orientations would also be possible, however the parallel arrangement is particularly space-saving.

[0071] In a preferred embodiment, the further flow-guiding element runs parallel to the side surface of the coater in the first end position and is flush with it, such that the side surface and an outer contour of the further flow-guiding element form a common guiding surface for the introduced process gas flow.

[0072] In this way, a continuously flush guide surface is provided for the process gas flow, in order to promote a turbulence-free process gas flow.

[0073] In a preferred embodiment, the flow guiding device comprises a bearing assembly attached to the process chamber with a drive unit by which the two flow guiding elements are mounted and which is configured to move the flow guiding elements relative to the process chamber in such a way that access from the first area to the second area of ​​the interior of the process chamber is opened or closed.

[0074] In this way, the flow guide elements themselves can be moved to provide access to the process area, for example to remove manufactured workpieces or to clean the process area.

[0075] Preferably, the flow-guiding elements are raised or lowered relative to the process chamber. This is particularly suitable when designed as flexible surface elements, preferably with a restoring weight, as this ensures that they do not become tangled or crumpled during the movement.

[0076] The lifting and lowering direction preferably runs vertically, i.e., parallel to the Earth's gravitational field.

[0077] In a preferred embodiment, the bearing arrangement of the flow guide device comprises a driveable shaft to which the flow guide elements are attached, wherein the flow guide elements can be rolled onto or off the shaft by rotation of the shaft. are such that access from the first area to the second area of ​​the interior of the process chamber is open in a rolled-up state and closed in a rolled-up state.

[0078] In this way, a particularly simple handling device for the flow guide elements is provided, which allows for particularly space-saving storage of the flow guide elements, since they are "rolled up".

[0079] Preferably, the machine tool comprises one or more further flow guide devices according to one of the described embodiments, wherein these are preferably positioned opposite each other across the construction area of ​​the machine tool in order to at least partially define the process area within the process chamber.

[0080] According to a second aspect of the invention, a flow guide device is used for Provided for use in a machine tool set up for additive manufacturing, in particular according to the first aspect of the invention.

[0081] The flow guide device comprises at least one (first) flow guide element and another flow guide element, which can be attached within a process chamber of a machine tool for the layer-by-layer additive manufacturing of workpieces and can be used as guide elements for a process gas flow through the process chamber, wherein at least the (first) flow guide element is elastically deformable between a first position in which the flow guide element has a first outer contour geometry and a second position in which the flow guide element has a second outer contour geometry that differs from the first.

[0082] In this way, an existing additive manufacturing machine can be quickly and easily extended or retrofitted with a device that guides the process gas flow, namely the flow guide, in order to optimally adapt the interior to the process gas flow without major structural modifications. The advantages of using the flow guide element or flow guide described above apply analogously here.

[0083] The designs of the flow-guiding elements, for example as flexible surface elements, have already been described above, which is why a repetition is omitted here.

[0084] Preferably, the flow guidance device comprises a restoring weight attached to one of the two flow guidance elements; more preferably, the flow guidance device comprises a restoring weight attached to each flow guidance element.

[0085] Preferably, the two flow-guiding elements run largely parallel to each other, in particular as parallel surfaces, with a distance between the two surfaces in The normal direction dimension is smaller than the longitudinal or lateral dimensions of the flow-guiding elements. In particular, the distance is a maximum of 5%, preferably a maximum of 1%, and most preferably a maximum of 0.1% of the length or width of one of the two flow-guiding elements.

[0086] Preferably, the flow guide device comprises a bearing device with a Drive unit by which the two flow guide elements are mounted and which is designed to move the flow guide elements relative to the process chamber, in particular to raise and / or lower them.

[0087] Preferably, the bearing arrangement of the flow guide device comprises a driveable shaft to which the flow guide elements are attached, wherein the flow guide elements can be rolled onto or off the shaft by rotation of the shaft.

[0088] Further aspects and their advantages, as well as more specific examples of the aforementioned aspects and features, are described below with the aid of the drawings shown in the attached figures.

[0089] Figs. 1A to 3 show a first embodiment of the machine tool according to the invention in different views and different positions of a coater of the machine tool.

[0090] Fig. 4 shows a second embodiment of the machine tool according to the invention in a side view.

[0091] Figs. 5A and 5B show a section of a third embodiment of the machine tool according to the invention in a side view.

[0092] It is emphasized that the present invention is in no way limited to the embodiments and features described below. The invention further comprises modifications of the aforementioned embodiments, in particular those resulting from modifications and / or combinations of individual or multiple features of the described embodiments within the scope of protection of the independent claims. Detailed character description

[0093] Figs. 1A and 1B show a first embodiment of the machine tool 100 according to the invention in a side view for two different positions of a coater 60 of the machine tool 100 in an xy-plane of the right-handed x,y,z coordinate system introduced for direction indication.

[0094] The machine tool 100 is set up for the layer-by-layer additive manufacturing of workpieces, in the course of which material 22 located on a carrier 21 is added to a height a building area 20 of the machine tool 100 is successively solidified into layers of the workpiece to be manufactured by irradiation, for example by fusing or sintering individual material particles, usually using an optical, mostly laser-based irradiation device (not shown here).

[0095] The machine tool 100 comprises a process chamber 10, which surrounds an interior space 30 in which the manufacturing (additive construction) of the workpieces takes place, the said build area 20 with a carrier 21 movable in the y-direction for the material 22, a process gas device 40 (see Fig. 3) and a flow guide device 50.

[0096] The process chamber 10 comprises a floor element 11 that is almost flush with the build area 20, four side elements 12a-d (two shown in Fig. 1A and 1B) and a ceiling element 13 and, together with the build area 20, encloses the interior space 30 in which the manufacturing takes place. In this way, the interior space 30, separated from the environment of the machine tool 100, is provided in which the manufacturing can take place largely independently of the environmental conditions.

[0097] To reliably remove the impurities and pollutants (soot, exhaust gases, and other manufacturing byproducts) generated during production in the enclosed interior space 30, and thus ensure constant manufacturing conditions within the interior space 30, the process gas device 40 is designed to introduce a process gas stream 41 into the process chamber 10 during the additive manufacturing process. The process gas stream 41 carries away the aforementioned impurities and pollutants and, by way of example, flows as a parallel flow in the z-direction.

[0098] To guide the process gas flow 41 through the process chamber 10 in a targeted and stable manner, at least one (first) flow guide element 51 is used, which is fixed inside the process chamber 10 and is elastically deformable between a first position in which the flow guide element 51 has a first outer contour geometry (see Fig. 1A) and a second position in which the flow guide element 51 has a second outer contour geometry that differs from the first (see Fig. 1B). The outer contour of the flow guide element 51 forms a flow interface for the process gas flow 41, which is guided along this from an inlet 41 to an outlet 43 of the process gas device (see Fig. 3).

[0099] Stable, in this context, means largely free of turbulence that could disturb the material 22 and thus lead to a deterioration in manufacturing quality. Consequently, there is a strong interest in guiding the process gas flow 41 through the process chamber 10 as stably as possible, parallel to the build area 20.

[0100] The flow guide element 51 divides the interior 30 of the process chamber 10 into at least a first area 31 (process area), in which the actual manufacturing takes place, and a second area 32, which is largely separated from it. The process gas flow 41 flows only through the first area 31, whereby the flow guide element 51 reliably shields interference sources (e.g., additional sensors or actuators) located in the second area 32 from the process gas flow 41. This makes the design of the second area 32, in particular the arrangement and shape of the machine tool 100 components located there, essentially independent of the process gas flow 41.

[0101] The flow guide element 51 runs parallel to the side element 12a of the process chamber 10 (in the y-direction) and orthogonally to the construction area 20 or to the bottom element 11 and is designed as a flexible surface element, in particular as a foil element.

[0102] The flow guide element 51 is designed as part of the flow guide device 50, which in turn comprises a further (second) flow guide element 53, return weights 52, 54, a bearing device 55 for the flow guide elements 51, 53, and guide elements 56a, 56b for lateral support and for guiding a traversing movement of the flow guide elements 51, 53. The bearing device 55 and guide elements 56a, 56b will be explained in more detail later in connection with Fig. 2.

[0103] The restoring weights 52, 54 are attached to the underside of the flow guide elements 51, 53, their weight forces acting as restoring forces which always attempt to return the flow guide elements 51, 53, designed as flexible surface elements, to the vertical orientation shown in Fig. 1A.

[0104] The outer contours of the flow guide elements 51, 53 serve as flow interfaces for the process gas flow 41, with the two together defining a flow interface parallel to the yz-plane in the first position shown in Fig. 1A, which almost completely separates the first region 31 from the second region 32. Here, a lower edge of the first flow guide element 31 is almost flush with the bottom element 11 of the process chamber 10.

[0105] Due to the deformable design of the first flow guide element 51, it can be reversibly or elastically deformed in a simple and almost resistance-free manner between the first position shown in Fig. 1A and the second position shown in Fig. 1B.

[0106] The elastic deformation is caused by a traversing movement of the coater 60, which can be moved translationally (T) parallel to the build area 20 between a first end position 61 and a second end position 62. The coater 60 applies layers of material to the build area 20, usually via a coater lip or brush, with which the material 22 is drawn out uniformly to a predetermined thickness. Such a The process of applying and removing a layer of material must take place prior to each manufacturing step of an individual layer of the workpiece to be manufactured.

[0107] The coater 60 is thus in continuous use and should therefore, with a view to short production times, have to cover the shortest possible travel distances. Consequently, it is advantageous not to remove the coater 60 from and reinsert it into the process chamber 10 each time, but to leave it there, which in turn makes it a potential source of interference for the process gas flow 41 flowing through the process chamber 10 during production.

[0108] To resolve this conflict, the use of the deformable first flow guide element 51 is particularly suitable, which, as shown in Figures 1A and 1B, can be pushed away from the coater 60 as soon as the latter moves into its first end position 61. Thus, there is no need to move the first flow guide element 51, which is directly adjacent to the build area 20, so that the coater 60 can leave the area above the build space 20, thereby implementing a passive adaptation of the first flow guide element 51 to the movable component coater 60.

[0109] If the first flow guide element 51 is designed as a flexible surface element, the deformation by the coater 60 requires only a minimum of force, so that its movement is not unnecessarily disturbed.

[0110] In the second position shown in Fig. 1B with a second outer contour geometry of the first flow guide element 51, this element conforms to an outer contour of the coater 60, whereby a section above it is pulled away from its vertical starting position.

[0111] Upon reaching the first end position 61, the right side surface of the coater 60 takes the place of the outer contour of the first flow guide element in the first position shown in Fig. 1A.

[0112] In order to provide a flush, vertically extending flow boundary surface for the process gas flow 41 in this case, the second flow guide element 53 is used, which in Fig. 1B is located above the coater 60 and is almost flush with it, and forms the aforementioned vertical flow boundary surface with its right side surface.

[0113] On the side of the second end position 62 of the coater, a flow boundary surface is implemented by a rigid partition 70, which in an alternative embodiment according to Fig. 4 can be replaced by a further flow guide device, and which creates a third area 33 in the interior 30 of the process chamber.

[0114] The machine tool according to the invention thus provides a possibility for guiding the flow of the process gas stream, which, among other things, allows for minimal travel distances. This allows it to be used without requiring additional actuators and makes parts of the interior particularly adaptable to the process gas flow.

[0115] This allows for a reduction in manufacturing times, maintenance effort, and the associated costs. Furthermore, a modular flow line can be provided that is largely independent of the overall shape of the process chamber 10 and can therefore be used for a wide variety of machine tools.

[0116] Fig. 2 shows the machine tool 100 according to the first embodiment from Fig. 1A in a side view rotated by 90 degrees in the yz plane.

[0117] As can be seen from Fig. 2, the lower ends of the flow guide elements 51, 53 are spaced apart in the vertical y-direction to allow entry of the coater 60, in which it only deforms the first flow guide element 51. This also closes flush with the bottom element 11 of the process chamber 10.

[0118] Lateral end sections of the flow guide elements 51, 53 are guided in the vertical y-direction by guide elements 56a, 56b (see also Figs. 1A and 1B) attached to the side elements 12c, 12d of the process chamber 10 and are fastened at the top via the bearing device 55 inside the process chamber 10. The first flow guide element 51 is free of the lateral guide elements 56a, 56b in the position shown in Fig. 2, so as not to obstruct deformation by the coater 60 (see Fig. 1B).

[0119] The bearing device 55 is designed as a shaft 55a, which is rotatably connected to the process chamber 10 parallel to the z-direction via a bearing 55b installed in the side elements 12c, 12d. The flow guide elements 51, 53 are attached to the shaft 55a in such a way that they can be wound onto and unwound from the shaft 55a, so that the lower ends of the flow guide elements 51, 53 can be raised and lowered in the vertical y-direction in order to open and close access from the first area 31 to the second area 32, for example for removing finished workpieces from the build area 20. Fig. 2 shows a quantity 51', 53' of the flow guide elements 51, 53 partially wound onto the shaft 55a.

[0120] The bearing device 55 comprised a drive unit 55c, preferably electric, by means of which the shaft 55a can be rotated about a rotation axis R parallel to the z-direction in order to roll the flow guide elements 51, 53 up and down. In this process, the lateral guide elements 56a, 56b serve to guide the flow guide elements 51, 53 in a controlled manner.

[0121] Fig. 3 shows the machine tool 100 according to the first embodiment from Fig. 1A in a top view in the xz plane, for better illustration of the process gas flow 41 flowing through the process chamber 10.

[0122] The process gas flow device 40 comprises an inlet 42 arranged on the side of the side element 12d, through which the process gas flow 41 enters the The process chamber 10 is introduced, more precisely into the first area 31 of the interior 30. One inlet direction runs parallel to the plane formed by the flow guide elements 51, 53 in the position shown in Fig. 1A, which runs parallel to the yz-plane.

[0123] Starting from the inlet 42, the process gas flow 41, represented by the selected arrow, flows through the first area 31 to an outlet 43 of the process gas device 40.

[0124] The flow boundary surfaces of the parallel flow of the process gas stream 41 shown in Fig. 3 are the flow guide elements 51, 53 on the left, the side surfaces of the coater 60 and the partition wall 70, as well as the build area 20 and the bottom element 11 (see also Fig. 1A).

[0125] These elements are designed in such a way that they form continuous and flat flow interfaces along which the process gas flow flows without turbulence and preferably without flow separation, in order to ensure a stable and turbulence-free flow condition in the first area 31 (process area).

[0126] This prevents the material 22 located on the building area 20 from being stirred up, which in turn enables a consistent manufacturing quality of the individual workpiece layers, as this prevents local variations in the thickness of an applied material layer.

[0127] Fig. 4 shows a second embodiment of the machine tool 100 according to the invention in a side view in an xy-plane.

[0128] In comparison to the first embodiment, the present machine tool 100 differs in that the separating element 70 on the right side in the side view (see Fig. 1A) has been replaced by a further flow guide device 50, which is essentially identical in construction to the first, left-side flow guide device 50.

[0129] In this way, two flow paths of the process gas stream 41 are formed using the proposed deformable flow guide element, between which the coater 60 can be moved back and forth without having to move the flow guide elements themselves, thus eliminating the coater as a source of disturbance for the process gas stream. This allows for particularly short travel distances of the coater without risking destabilization of the process gas stream.

[0130] Figs. 5A and 5B show a section of a third embodiment of the machine tool 100 according to the invention in a side view in an xy-plane for two different positions of a coater 60.

[0131] In comparison to the first embodiment, the present machine tool 100 differs in that on the underside of the right-hand side in the side view A flap 72 is arranged in the separating element 70 (see Fig. 1A) and is rotatably mounted about a pivot joint 71.

[0132] The upper part of the machine tool 100, which is not shown in the views in Fig. 5A and 5B, is identical to that of the first embodiment from Fig. 1A, and the left-side flow guide device is also identical, so that no further explanations are necessary at this point.

[0133] Flap 72 is attached to the partition wall via the pivot joint 71 in such a way that it can be rotated by a movement of the coater 60 between a vertical starting position (see Fig. 5B), in which it separates the first area 31 from the third area 33 of the interior 30, and a horizontal position (see Fig. 5A).

[0134] The rotary bearing 71 preferably comprises a return element, for example a spring element, by which the flap 72 (in addition to the weight force acting on it) is reliably returned to its vertical starting position when it loses contact with the coater 60, in order to form a flat flow interface for the process gas flow 41 again.

[0135] In the aforementioned vertical starting position, the outer contours of the partition wall 70 and the flap 72 preferably form a flat, in particular vertically extending, flow boundary surface for the process gas flow 41.

[0136] In said horizontal position, the coater 60 has reached its second end position 62 and pushed the flap 72 out of the vertical starting position into the third area 33. The machine tool 100 is preferably designed such that the outer contours of the partition 70 and the coater 60 in its second end position 62 form a flat, in particular vertically extending, flow interface for the process gas flow 41, as is also the case for the configuration shown in Fig. 1A.

[0137] The rotatable flap 72 thus provides a closable access for the coater 60 to the third area 33 of the interior 30, whereby a flat and essentially continuous flow interface is always present. This allows the guidance of the process gas flow 41 to be improved compared to the first embodiment, at least in the case that the coater is located on the left side in its first end position 61.

[0138] Above, exemplary embodiments of the present invention and their advantages have been described in detail with reference to the accompanying figures.

[0139] Finally, it is emphasized again that the present invention is in no way limited to the embodiments and features described above. The invention further comprises modifications of the aforementioned embodiments, in particular those consisting of modifications and / or combinations of one or more Features of the described embodiments within the scope of protection of the independent claims will emerge. List of reference symbols 10th Trial Chamber 11 floor element 12a-d Page elements 13 Ceiling element 20 building plots 21 movable carriers 22 Material 30 Interior of the trial chamber 31 First area (process area) 32 second area 33 third area 40 Process gas device 41 Process gas flow 42 Admission 43 Outlet 50 Flow guide device 51, 51' first flow guide element 52 first reset weight 53, 53' second flow guide element 54 second return weight 55 Storage device 55a wave 55b Warehouse 55c drive 56a, b Guide elements 60 coaters 61 first final position 62 second end position 70 partition wall 71 Swivel joint 72 flap 100 machine tools

Claims

CLAIMS 1. Machine tool (100) for the layer-by-layer additive construction of workpieces, comprising: - a process chamber (10) in which the additive construction of workpieces takes place; - a process gas device (40) which is configured to introduce a process gas flow (41) into the process chamber (10) during the additive build-up; characterized by a flow guide element (51) for the process gas flow (41) which is fastened within the process chamber (10) and which is elastically deformable between a first position in which the flow guide element (51) has a first outer contour geometry and a second position in which the flow guide element (51) has a second outer contour geometry which differs from the first 2. Machine tool (100) according to claim 1, characterized in that the flow guiding element (51) is designed such that the first outer contour geometry corresponds to a flat surface.

3. Machine tool (100) according to claim 2, characterized in that the flow guide element (51) is arranged in the first position such that the flat surface runs parallel to an introduction direction of the introduced process gas flow (41).

4. Machine tool (100) according to at least one of claims 1 to 3, characterized in that the flow guiding element (51) is designed as a flexible surface element.

5. Machine tool (100) according to claim 4, characterized in that the flexible surface element is a film element or a fabric element.

6. Machine tool (100) according to claim 4, characterized in that the flexible surface element is a metallic sheet metal element, in particular a spring steel strip.

7. Machine tool (100) according to at least one of claims 1 to 6, characterized in that the flow guide element (51) in the first position divides an interior space (30) of the process chamber (10) at least into a first region (31) and a second region (32), wherein the first region (31) is a process region in which the additive build-up takes place, wherein the process gas device (40) is configured to introduce the process gas flow (41) into the first region (31).

8. Machine tool (100) according to claim 7, characterized in that a construction field (20) of the machine tool (100), on which the layered construction takes place, is arranged entirely in the first region (31) 9. Machine tool (100) according to one of claims 7 or 8, characterized in that the process chamber (10) comprises lateral housing elements (12a-d), a top-side housing element (13) and a bottom-side housing element (11), wherein the housing elements and the flow guide element (51) are arranged relative to one another in such a way that in the first position of the flow guide element (51), the introduced process gas flow (41) flows as a parallel flow along the flow guide element (51) through the first region (31) of the interior (30) of the process chamber (10) 10. Machine tool (100) according to at least one of claims 1 to 9, characterized in that the machine tool (100) comprises a coater (60) which is movable relative to the process chamber (10) between a first and a second end position (61, 62), which is designed to apply material layers for the additive construction to a construction field (20) of the machine tool (100) in the process chamber (10), and is further designed to elastically deform the flow guide element (51) between the first position and the second position by a displacement movement.

11. Machine tool (100) according to claim 10, characterized in that the flow guide element (51) is moved into the second position when the coater (60) is in its first end position (61), wherein the flow guide element (51) rests at least partially against the coater (60) 12. Machine tool (100) according to claim 11, characterized in that a side surface of the coater (60) in the first end position (61) forms a guide surface for the introduced process gas flow (41) 13. Machine tool (100) according to claims 1 and 12, characterized in that the side surface of the coater (60) in the first end position (61) and an outer contour of the flow guide element (51) in the first position lie in a same plane relative to the process chamber (10).

14. Machine tool (100) according to at least one of claims 1 to 13, characterized in that a restoring weight (52) is attached to the flow guide element (51) in such a way that its weight acts as a restoring force for returning the flow guide element (51) to the first position 15. Machine tool (100) according to at least one of the preceding claims, characterized in that the flow guiding element (51) is designed as part of a flow guiding device (50) of the machine tool (100), which, in addition to the flow guiding element (51), comprises at least one further flow guiding element (53) for the process gas flow (41).

16. Machine tool (100) according to claim 15, characterized in that the further flow guide element (53) is arranged parallel to the flow guide element (51) in the first position 17. Machine tool (100) according to claim 12 and one of claims 15 or 16, characterized in that the further flow guide element (53) runs parallel to the side surface of the coater (60) in the first end position (61) and is flush with it, such that the side surface and an outer contour of the further flow guide element (53) form a common guide surface for the introduced process gas flow (41).

18. Machine tool (100) according to claim 7 and one of claims 15 to 17, characterized in that the flow guiding device (50) comprises a bearing device (55) fastened to the process chamber (10) with a drive unit (55c), by means of which the two flow guiding elements (51, 53) are mounted and which is designed to move the flow guiding elements (51, 53) relative to the process chamber (10) in such a way that an access from the first region (31) into the second region (32) of the interior (30) of the process chamber (10) is opened or closed.

19. Machine tool (100) according to claim 18, characterized in that the bearing device (55) of the flow guiding device comprises a drivable shaft (55a) to which the flow guiding elements (51, 53) are fastened, wherein the flow guiding elements (51, 53) can be rolled onto or off the shaft (55a) by rotation of the shaft (55a) in such a way that the access from the first region (31) to the second region (32) of the interior (30) of the process chamber (10) is opened in a rolled-up state (51', 53') and closed in an unrolled state 20. Flow guiding device (55) for use in a machine tool (100) according to at least one of claims 15 to 19.

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