Recoater system for laying out a powder bed in a process chamber of an additive manufacturing apparatus

Abstract

The present invention relates to a recoater system (11) for laying out a powder bed in a process chamber (1) of an additive manufacturing ap- paratus, wherein the recoater system (11) comprises: - a first track (13) and a second track (15) extending parallel to each other in a first direction (x), wherein the first track (13) and the sec- ond track (15) have a track distance (D) to each other in a second direction (y) that extends transverse to the first direction (x), and - a recoater unit (21) bridging the track distance (D), wherein the re- coater unit (21) comprises a first mounting element (23a) for mount- ing the recoater unit (21) to the first track (13) and a second mount- ing element (23b) for mounting the recoater unit (21) to the second track (15), so that the recoater unit (21) is guided by the first track (13) and the second track (15) to be movable in the first direction (x), wherein at least one of the first mounting element (23a) and the second mounting element (23b) comprises a first flexure hinge (35) defining a first flexure hinge axis (37) and a second flexure hinge (39) defining a second flexure hinge axis (41), wherein the first flexure hinge axis (37) and the second flexure hinge axis (41) extend transverse to the second direction (y) in parallel to each other, allowing a thermal expansion of the re- coater unit (21) in the second direction (y).

Description

[0001] Applicant: Nikon SLM Solutions AG

[0002] Title: Recoater system for laying out a powder bed in a process chamber of an additive manufacturing apparatus

[0003] Our Ref.: SLMP 3845 WO

[0004] Description

[0005] TECHNICAL FIELD

[0006]

[0001] The present disclosure is directed to a recoater system for laying out a powder bed in a process chamber of an additive manufacturing 5 apparatus. In particular, the present disclosure relates to a recoater system in additive manufacturing facilities for serial production at an industrial scale. More particularly, the additive manufacturing apparatus is preferably configured to apply laser powder bed fusion (LPBF) as the additive manufacturing technique for producing metallic objects.

[0007] 10 BACKGROUND

[0008]

[0002] Additive manufacturing of three-dimensional objects is often referred to as 3D-printing. A specific form of additive manufacturing is laser powder bed fusion (LPBF), in which a layer of raw material powder is exposed to a high-energy beam of electromagnetic radiation, such as, for 15 example, a laser beam or a particle beam, for selectively sintering and / or melting particles of the raw material powder. The three-dimensional objects are manufactured by sequentially sintering and / or melting layer-by-layer of raw material powder.

[0009] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

[0003] Compared to conventional manufacturing techniques like moulding, additive manufacturing of a three-dimensional objects consumes considerably more time. Therefore, in the early days of 3D-printing, additive manufacturing was only applied for prototyping or for a small 5 number of individual objects. However, as additive manufacturing offers the possibility to design and produce components than cannot be produced by other conventional manufacturing techniques, there is a high demand for using additive manufacturing for serial production at an industrial scale.

[0010] 10

[0004] One solution to speed up additive manufacturing is using several lasers in parallel. The largest additive manufacturing machines currently on the market use up to 12 lasers in parallel in a single process chamber. Using several lasers in parallel, however, implies a significant heat development within the process chamber during additive manufacturing. In particular, the recoater may become very hot and may thus thermally expand. This is particularly problematic for a large powder bed having a width of 50 cm or more to be bridged by the recoater.

[0011]

[0005] WO 2022 / 090086 Al describes two different types of recoaters and how they are operated in combination with a dosing feeder. The 20 problem of thermal expansion of a long recoater is not addressed in WO 2022 / 090086 Al . WO 2020 / 074127 Al describes a powder distributor device that tries to tackle the problem of thermal expansion by a spring suspension arrangement. A spring suspension arrangement, however, has the disadvantage that, on the one hand, high pretension forces are 25 needed for laying out the powder bed with precise planarity. On the other hand, high pretension forces lead to structural stress in the recoater, in particular upon thermal expansion, which may deteriorate the powder bed quality.

[0012] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

[0006] It is therefore an object of the present invention to provide a recoater for laying out a powder bed in a process chamber of an additive manufacturing apparatus, wherein the recoater system allows for laying out the powder bed with high precision planarity, i.e. with a tolerance of 5 less than 100 or 50 microns for the planarity of the powder bed, even upon thermal expansion of the recoater.

[0013] SUMMARY

[0014]

[0007] This problem is solved by a recoater system according to the accompanying independent claim. Preferred embodiments can be de10 duced from the dependent subclaims, the description and the figures.

[0015]

[0008] According to the present disclosure, a recoater system is provided for laying out a powder bed in a process chamber of an additive manufacturing apparatus, wherein the recoater system comprises:

[0016] a first track and a second track extending parallel to each other in a first direction, wherein the first track and the second track have a track distance to each other in a second direction that extends transverse to the first direction, and

[0017] a recoater unit bridging the track distance, wherein the recoater unit comprises a first mounting element for mounting the recoater 20 unit to the first track and a second mounting element for mounting the recoater unit to the second track, so that the recoater unit is guided by the first track and the second track to be movable in the first direction,

[0018] wherein at least one of the first mounting element and the second 25 mounting element comprises a first flexure hinge defining a first flexure hinge axis and a second flexure hinge defining a second flexure hinge axis, wherein the first flexure hinge axis and the second flexure hinge axis extend transverse to the second direction in parallel to each other,

[0019] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025allowing a thermal expansion of the recoater unit in the second direction.

[0020]

[0009] The flexure hinges of the first mounting element and / or the second mounting element provide a flexibility of the recoater to thermally ex5 pand in the second direction, but a rigidity in other directions to allow for laying out the powder bed with high precision planarity even upon thermal expansion of the recoater. The first mounting element and / or the second mounting element may be an integral part of the recoater unit or an exchangeable part of the recoater unit. Preferably, the first mount10 ing element and / or the second mounting element is an exchangeable mounting bracket of the recoater unit. An exchangeable mounting bracket is advantageous to replace the flexure hinges before too many stress cycles may cause structural fatigue. The first mounting element and / or the second mounting element in form of a mounting bracket is preferably Z-shaped. Preferably, the first mounting element and the second mounting element are mirror-identically shaped.

[0021]

[0010] Optionally, said at least one of the first mounting element and the second mounting element may further comprise a third flexure hinge defining a third flexure hinge axis and a fourth flexure hinge defining a fourth 20 flexure hinge axis, wherein the first flexure hinge, the second flexure hinge, the third flexure hinge and the fourth flexure hinge define a straight-line mechanism, in particular a Sarrus linkage or a Roberts linkage. This is particularly beneficial to keep the vertical position of the recoater unit stable during thermal expansion.

[0022] 25

[0011] Optionally, the first flexure hinge axis and the second flexure hinge axis may have a hinge axis distance to each other, wherein the hinge axis distance is at least 5% of the track distance. The longer the hinge axis distance is, the higher the leverage is for providing flexibility to expand in the second direction. However, a too high leverage transverse to the Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025second direction may impair precise positioning of the recoater unit. So, the hinge axis distance is preferably less than or equal to 20% of the track distance.

[0023]

[0012] Optionally, the first flexure hinge and the second flexure hinge 5 may be part of a plurality of flexure hinges having parallel flexure hinge axes, wherein the plurality of flexure hinges is arranged in a series configuration, wherein a flexure hinge pivoting direction alternates among the flexure hinges along the series configuration. Such a plurality of parallel flexure hinge axes may provide more rigidity in other directions while allowing thermal expansion in the second direction.

[0024]

[0013] Optionally, the series configuration may follow a meandering path of structural integrity. The path of structural integrity is preferably meandering in a plane transverse to the second direction.

[0025]

[0014] Optionally, the first flexure hinge and the second flexure hinge 15 may comprise a tapering of titanium-containing material. The base material of the recoater unit may be aluminium for being lightweight and the general rigidity it provides. However, the coefficient of linear thermal expansion (CLTE) of aluminium is 23.1 ■ 10“6K'“1, which is higher than for many other metallic materials. As an aluminium-based recoater unit may have a length in the second direction of 800 mm or more and may heat up during the additive manufacturing process by 50°C or more, the thermal expansion of the recoater unit may be about one or more millimetres in the second direction. The titanium-containing material of the first flexure hinge and / or the second flexure hinge may be advantageous to 25 achieve a longer lifetime, or more working cycles compared to an aluminium-based or steel-based alloy.

[0026]

[0015] Optionally, said at least one of the first mounting element and the second mounting element may comprise an inner mounting section, an Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025outer mounting section and at least one intermediary mounting section, wherein the at least one intermediary mounting section has a first intermediary mounting section end being connected to the inner mounting section, and wherein the at least one intermediary mounting section has 5 a second intermediary mounting section end being connected to the outer mounting section, wherein the at least one intermediary mounting section extends essentially transverse to the second direction, wherein the first flexure hinge is displaceable by a displacement distance in the second direction relative to the second flexure hinge.

[0027] 10

[0016] Optionally, said at least one of the first mounting element and the second mounting element further comprises a third flexure hinge defining a third flexure hinge axis and a fourth flexure hinge defining a fourth flexure hinge axis, wherein the at least one intermediary mounting section is one of a first intermediary mounting section and a second intermediary mounting section, wherein the second flexure hinge and the third flexure hinge connect the first intermediary mounting section and the second intermediary mounting section with each other, wherein the third flexure hinge is displaceable in the second direction relative to the fourth flexure hinge by said displacement distance.

[0028] 20

[0017] Optionally, the first intermediary mounting section and / or the second intermediary mounting section may extend in a third direction transverse to both the first direction and the second direction.

[0029]

[0018] According to another aspect of the present invention, an additive manufacturing apparatus is provided comprising a process chamber 25 and a previously described recoater system for laying out a powder bed in the process chamber.

[0030] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

[0019] Optionally, the first track and the second track of the recoater system may have a vertical distance to the powder bed, wherein the vertical distance is at least 5% of the track distance of the recoater system.

[0031]

[0020] Optionally, the powder bed may have a powder bed width of at 5 least 50 cm, wherein the track distance of the recoater system is larger than the powder bed width.

[0032]

[0021] Optionally, the powder bed may have a powder bed length of at least 50 cm, wherein the first rack and the second track of the recoater system have a track length in the first direction that is larger than the powder bed length.

[0033] SUMMARY OF THE DRAWINGS

[0034]

[0022] Embodiments of the present disclosure will now be described by way of example with reference to the following figures of which:

[0035] 15 Fig. 1 shows a view from the front into a process chamber of an additive manufacturing machine with an embodiment of an inventive recoater system;

[0036] Figs. 2a,b,c show different schematic views of an example of an inventive recoater system;

[0037] Fig. 3 shows a perspective view of a preferred embodiment of the first mounting element or the second mounting element in form of an exchangeable mounting bracket of 25 an example of an inventive recoater system;

[0038] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025Figs. 4a,b,c show different views of the mounting bracket shown in Fig. 3;

[0039] Figs. 5a,b,c show schematically a first general principle of an in- 5 ventive flexure hinge arrangement;

[0040] Figs. 6a,b,c show schematically a second general principle of an inventive flexure hinge arrangement; and

[0041] 10 Figs. 7a,b,c show schematically a third general principle of an inventive flexure hinge arrangement.

[0042] DETAILED DESCRIPTION

[0043]

[0023] Fig. 1 shows schematically a process chamber 1 of an additive manufacturing apparatus for additively manufacturing a three-dimensional object 3. To facilitate the orientation in the figures, a right-handed Cartesian coordinate system is shown in each figure, wherein the z-axis extends essentially vertically upward, the x-axis extends essentially horizontally backward, and the y-axis extends essentially horizontally side20 ways to the left when seen backwardly from a position in front of the process chamber 1. It should be noted that these axes can be arbitrarily defined and constitute no limitation regarding the spatial orientation of the process chamber 1. The spatial terms “forward”, “backward”, “front”, “rear”, “up”, “bottom”, etc. thus follow an arbitrarily defined convention in this disclosure. The view into the process chamber 1 in Fig. 1 is from an open process chamber door that can be opened to allow manual access to the process chamber 1.

[0044]

[0024] The additive manufacturing is performed by a laser system (not shown) arranged at a process chamber ceiling 5 for directing one or 30 preferably more laser beams downward onto a raw material powder

[0045] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025bed for selectively sintering / melting the raw material powder to add layer-by-layer to the three-dimensional object 3. Once a layer is finished, a vertically movable building platform 7 is lowered by one layer-thickness into a build cylinder arranged underneath a bottom opening 9 of the 5 process chamber 1. Then, a new layer of raw material powder is deposited on the previously manufactured layer.

[0046]

[0025] The deposition of new layers of raw material powder is performed by a recoater system 11. The recoater system 11 of a first type as shown in the figures may comprise a refillable reservoir of raw material powder 10 for dropping a dosed amount of raw material powder during a linear motion in x-direction to lay out the raw material powder bed. Alternatively, or in addition, the recoater system 11 of a second type may comprise a rake to distribute and flatten a hill of raw material powder during a linear motion in x-direction to lay out the raw material powder bed.

[0047]

[0026] Irrespective of the type of recoater system 11 , the recoater system 11 comprises a first track 13 and a second track 15 that both extend parallel to each other in the x-direction. The first track 13 and the second track 15 are arranged at lateral side walls 17, 19 of the process chamber 1. Therefore, the first track 13 and the second track 15 have a track dis20 tance D to each other in the y-direction that is approximately equal to a process chamber width in the y-direction. In the shown example, the track distance D is about 80 cm. In the x-direction, the first track 13 and the second track 15 have a track length L that may extend essentially over the full length of the process chamber 1 in the x-direction. In the shown example, the vertically movable building platform 7 has a quadratic shape in the xy-plane with rounded corners to accommodate a powder bed of the size 50x50 cm in the xy-plane. The track length L in x- direction is therefore significantly longer than the powder bed length in x-direction. Likewise, the track distance D is significantly larger than the 30 powder bed width in the y-direction. In the vertical z-direction, the first

[0048] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025track 13 and the second track 15 of the recoater system 11 have a vertical distance H to the powder bed. The vertical distance H is at least 5% of the track distance D of the recoater system 11. In the example shown in Fig. 1 , the vertical distance H is about 8 cm, which is about 10% of the 5 80 cm track distance D of the recoater system 11.

[0049]

[0027] The recoater system 11 further comprises a recoater unit 21 that bridges the track distance D, wherein the recoater unit 21 comprises a first mounting element 23a for mounting the recoater unit 21 to the first track 13 and a second mounting element 23b for mounting the recoater 10 unit 21 to the second track 15, so that the recoater unit 21 is guided by the first track 13 and the second track 15 to be movable in the x-direc- tion. It should be noted that the three-dimensional object 3 is shown in Fig. 1 within the process chamber 1 only for illustrative purposes and is usually not in the way of the motion path of the recoater unit 21. During additive manufacturing, the three-dimensional object 3 is lowered down into a build cylinder located below the bottom opening 9 of the process chamber 1 , into which the vertically movable building platform 7 is lowered. The movable range of the recoater unit 21 in the x-direction is essentially along the full track length L in x-direction for laying out a powder 20 bed in the process chamber 1.

[0050]

[0028] Figs. 2a-c show the recoater system 11 more schematically in a side view (Fig. 2a), in a top view (Fig. 2b), and in a front view (Fig. 2c). It should be noted that the process chamber 1 may heat up significantly during additive manufacturing, especially when a plurality of lasers is used in parallel to speed up the additive manufacturing process. Therefore, the recoater unit 21 may thermally expand when the process chamber 1 heats up during the additive manufacturing process. It is thus a challenge to mount the recoater unit 21 to the first track 13 and to the second track 15 in such a way that the powder bed can still be laid out 30 which high precision planarity, e.g. with a tolerance of less than 100 or 50

[0051] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025microns for the planarity of the powder bed, even upon a thermal expansion of the recoater unit 21.

[0052]

[0029] In the example shown in Figs.2a-c, the first mounting element 23a and the second mounting element 23b of the recoater unit 21 are imple5 mented in form of exchangeable mounting brackets having a Z-shape, wherein the first mounting element 23a and the second mounting element 23b are essentially mirror-identical to each other.

[0053]

[0030] Fig. 3 shows an embodiment of the first mounting element 23a. The second mounting element 23b may or may not be mirror-identical 10 to the first mounting element 23a. It is sufficient that the invention is implemented in only one of the first mounting element 23a and the second mounting element 23b. However, it is preferred that the invention is implemented in both the first mounting element 23a and the second mounting element 23b.

[0054]

[0031] The first mounting element 23a as shown in Fig. 3 comprises an inner mounting section 25 that extends here essentially in the horizontal xy- plane. The rest of the recoater unit 21 bridging the track distance D (not shown in Fig. 3) is to be fixed to the inner mounting section 25 of the first mounting element 23a. The first mounting element 23a further comprises 20 an outer mounting section 27 that also extends here essentially horizontal in the xy-plane, but with a vertical distance relative to the inner mounting section 25. The vertical distance bridges most part of the vertical distance H between the tracks 13, 15 and the powder bed. The outer mounting section 27 is slidably arranged on the first track 13 to allow a 25 linear motion of the recoater unit 21 in the x-direction. The first mounting element 23 further comprises at least one intermediary mounting section 29a, b,c that extend essentially vertical in the xz-plane to connect the inner mounting section 25 and the outer mounting section 27. The Z- shape of the first mounting element 23b, when seen in the x-direction, Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025results from the horizontal inner mounting section 25, the at least one vertical intermediary mounting section 29a, b,c and the horizontal outer mounting section 27.

[0055]

[0032] In the embodiment shown in Fig. 3, there are three intermediary 5 mounting sections 29a, b,c. In fact, there are five intermediary mounting sections 29a, b,c, but parallel sections that move identically to each other are denoted herein as the same section. It should be understood that any section may be implemented in form a plurality of parallel moving sections. In the example shown in Fig. 3, there are in total four first intermediary mounting sections 29a, four second intermediary mounting sections 29b and one third intermediary mounting section 29c. The first intermediary mounting sections 29a have each a first intermediary mounting section (bottom) end 31 being connected to the inner mounting section 25. The third intermediary mounting section 29c has a second 15 intermediary mounting section (top) end 33 being connected to the outer mounting section 27. The first intermediary mounting sections 29a, the second intermediary mounting sections 29b and the third intermediary mounting section 29c are connected to each other in such a way that they define a meandering path of structural integrity, wherein the meandering path of structural integrity extends in the vertical xz-plane. A bottom end of the first intermediary mounting sections 29a forms the first intermediary mounting section end 31. A top end of the first intermediary mounting sections 29a is connected to a top end of the second intermediary mounting sections 29b. A bottom end of the second inter25 mediary mounting sections 29b is connected to a bottom end of the third intermediary mounting section 29c. A top end of the third intermediary mounting section 29c forms the second intermediary mounting section end 33.

[0056] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

[0033] The first intermediary mounting sections 29a each comprise a first (bottom) flexure hinge 35 defining a first flexure hinge axis 37 and a second (top) flexure hinge 39 defining a second flexure hinge axis 41. Both the first flexure hinge axis 37 and the second flexure hinge axis 41 extend 5 transverse to the y-direction in the x-direction in parallel to each other.

[0057] The first flexure hinge 35 and the second flexure hinge 39 introduce a flexibility of the structure of the first mounting element 23a to allow a displacement of the inner mounting section 25 due to thermal expansion of the recoater unit 21 in the y-direction without moving the outer mounting 10 section 27 laterally in y-direction.

[0058]

[0034] The top end of the first intermediary mounting sections 29a could in principle be the second intermediary mounting section end 31 that is connected to the outer mounting sections 27. However, that would lead to a rotational movement of the first intermediary mounting section end 31 about the second (top) flexure hinge axis 41, which would result in a slight vertical motion of the inner mounting section 25. Such a vertical motion of the inner mounting section 25, however, is not desired and may impair the precision of the planarity of the powder bed. Therefore, it is advantageous that the second intermediary mounting sections 29b 20 comprise a third (top) flexure hinge 43 defining a third flexure hinge axis 45 and a fourth (bottom) flexure hinge defining a fourth flexure hinge axis 49. Thereby, a Roberts linkage is established as a straight-line mechanism that allows a lateral motion of the first intermediary mounting section end 31 in y-direction without any vertical motion in z-direction. The third intermediary mounting section 29c is simply a rigid structural member vertically connecting a bottom end of the second intermediary mounting sections 29b with the second intermediary mounting section (top) end 33.

[0059]

[0035] It should be noted that each of the first intermediary mounting 30 sections 29a has two flexure hinges 35 arranged in parallel to each other

[0060] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025and two second flexure hinges 39 arranged in parallel to each other.

[0061] Likewise, each of the second intermediary mounting sections 29b has two third flexure hinges 43 arranged in parallel to each other and two fourth flexure hinges 47 arranged in parallel to each other. It should be 5 noted that a single first flexure hinge 35, a single second flexure hinge 39, a single third flexure hinge 43, and / or a single fourth flexure hinge 47 could be sufficient to establish the straight-line mechanism in form of a Roberts linkage. However, a plurality of parallel first flexure hinges 35, second flexure hinges 39, third flexure hinges 43 and fourth flexure hinges 47 may be advantageous to provide the desired pivoting flexibility on the one hand and a structural rigidity in all other degrees of freedom. Preferably, the number of first flexure hinges 35, second flexure hinges 39, third flexure hinges 43 and fourth flexure hinges 47 is identical. Analogously, it is preferable that the number of first intermediary mounting sections 29a 15 is identical to the number of second intermediary mounting sections 29b.

[0062] It is also preferable that all first intermediary mounting sections 29a are shaped identically to each other and identical to all second intermediary mounting sections 29b.

[0063]

[0036] The first flexure hinge 35, the second flexure hinge 39, the third flex20 ure hinge 43 and the fourth flexure hinge 47 are arranged in a series configuration that follows the meandering path of a structural integrity, wherein a flexure hinge pivoting direction alternates between the flexure hinges 35, 39, 43, 47 along the series configuration. When thermal expansion of the recoater unit 21 pushes the inner mounting section 25 laterally outward in the negative y-direction, the first intermediary mounting section 29a performs simultaneously a counterclockwise rotation about the positive x-axis and a linear lateral outward displacement in the negative y-direction. This is facilitated by the first flexure hinge pivoting counterclockwise about the first flexure hinge axis 37 when seen in positive x- 30 direction while the second flexure hinge 39 pivots clockwise about the

[0064] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025second flexure hinge axis 41 when seen in positive x-direction. The second intermediary mounting section 29b performs simultaneously the corresponding counter movement, i.e. the third flexure hinge 43 pivots counterclockwise about the third flexure hinge axis 45 when seen in pos5 itive x-direction and the fourth flexure hinge 47 pivots clockwise about the fourth flexure hinge axis 49 when seen in positive x-direction, so that the second intermediary mounting section 29b performs a clockwise rotation about the fourth flexure hinge axis 49 when seen in positive x-di- rection. It will be understood that thermal shrinkage in y-direction leads 10 to the opposite motion of the Roberts linkage defined by the flexure hinges 35, 39, 43, 47. The vertical z-position of the inner mounting section 25 remains stable for all y-positions within an allowable range of thermal expansion. The allowable range of thermal expansion may be in the range of one or more millimetres.

[0065]

[0037] Figs. 4a-c show a side view (Fig. 4a) and first cross-sectional view through the cutting plane A-A (Fig. 4b) and second cross-sectional view through the cutting plane B-B (Fig. 4c). The structural gaps of the first mounting element 23a between the inner mounting section 25, the intermediary mounting sections 29a, b,c and the outer mounting section de20 fine the meandering path of structural integrity. The first mounting element 23a may be an additively manufactured part with a single integral one-piece structure. The allowable range of thermal expansion is limited by the smaller one of the y-width of the vertical gap 51 between the third intermediary mounting section 29c and the inner mounting section 25 25 and the y-width of the vertical gap 53 between the first / second intermediary mounting sections 29a, b and the outer mounting section 27.

[0066]

[0038] Figs. 5a-c show more schematically the principle straight-line mechanism of a Roberts linkage that is applied in the embodiment shown in Fig. 3 and Figs. 4a-c. The flexure hinges 35, 39, 43 and 47 allow

[0067] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025a lateral motion of the inner mounting section 25 relative to the outer mounting section 27 without any vertical movement in z-direction.

[0068]

[0039] Figs. 6a-c show another possible implementation of a straight-line mechanism, in which the intermediary mounting sections 29a, b,c are not 5 arranged in parallel, but nevertheless allow a lateral movement in y-di- rection without a vertical movement of the inner mounting section 25.

[0069]

[0040] Figs. 7a-c show yet another possible straight-line mechanism in form of a Sarrus linkage that allows a linear motion of the inner mounting sections 25 relative to the outer mounting section 27 without a vertical 10 displacement in z-direction. In this example, the second flexure hinge 39 and the third flexure hinge 43 may be combined to a single flexure hinge.

[0070]

[0041] It should be noted that it is advantageous for all embodiments that the first flexure hinge axis 37 and the second flexure hinge axis 41 have a hinge axis distance A to each other that is large enough to allow for a sufficient thermal expansion. It has shown that a hinge axis distance A between the first flexure hinge axis 37 and the second flexure hinge axis 41 should be at least 5% of the track distance D. A hinge axis distance between the third flexure hinge axis 45 and the fourth flexure hinge axis 49 is preferably equal to the hinge axis distance A.

[0071] 20

[0042] Where, in the foregoing description, integers orelements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such 25 equivalents. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional, preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

[0072] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

[0043] The above embodiments are to be understood as illustrative examples of the disclosure. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in 5 combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art and may be changed without 10 departing from the scope of the subject matter described herein, and this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0073]

[0044] In addition, "comprising" does not exclude otherelements or steps, and "a" or "one" does not exclude a plural number. Furthermore, characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps of other exemplary embodiments described above. Method steps may be applied in any order or in parallel or may constitute a part or a more detailed version of another method 20 step. It should be understood that there should be embodied within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of the contribution to the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the disclosure, which should be determined from the appended claims and their legal equivalents.

[0074]

[0045] List of reference numerals:

[0075] 1 process chamber

[0076] 3 three-dimensional object

[0077] 5 process chamber sealing

[0078] 30 7 building platform

[0079] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 20259 bottom opening of the process chamber

[0080] 11 recoater system

[0081] 13 first track

[0082] 15 second track

[0083] 5 17 first lateral side wall of the process chamber

[0084] 1 second lateral side wall of the process chamber

[0085] 21 recoater unit

[0086] 23a first mounting element

[0087] 23b second mounting element

[0088] 10 25 inner mounting section

[0089] 27 outer mounting section

[0090] 29a first intermediary mounting sections

[0091] 29b second intermediary mounting sections

[0092] 29c third intermediary mounting section

[0093] 15 31 first intermediary mounting section end

[0094] 33 second intermediary mounting section end

[0095] 35 first flexure hinge

[0096] 37 first flexure hinge axis

[0097] 39 second flexure hinge

[0098] 20 41 second flexure hinge axis

[0099] 43 third flexure hinge

[0100] 45 third flexure hinge axis

[0101] 47 fourth flexure hinge

[0102] 49 fourth flexure hinge axis

[0103] 25 51 vertical gap

[0104] 53 vertical gap

[0105] A hinge axis distance

[0106] D track distance

[0107] H vertical distance

[0108] 30 L track length

[0109] Patentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

Claims

Claims1. A recoater system (11) for laying out a powder bed in a process chamber ( 1 ) of an additive manufacturing apparatus, wherein the recoater system (11) comprises:5 a first track (13) and a second track (15) extending parallel to each other in a first direction (x), wherein the first track (13) and the second track (15) have a track distance (D) to each other in a second direction (y) that extends transverse to the first direction (x), and10 a recoater unit (21) bridging the track distance (D), wherein the recoater unit (21 ) comprises a first mounting element (23a) for mounting the recoater unit (21 ) to the first track ( 13) and a second mounting element (23b) for mounting the recoater unit (21 ) to the second track ( 15), so that the recoater unit (21 ) is guided by the first track (13) and the second track (15) to be movable in the first direction (x),wherein at least one of the first mounting element (23a) and the second mounting element (23b) comprises a first flexure hinge (35) defining a first flexure hinge axis (37) and a second flexure hinge 20 (39) defining a second flexure hinge axis (41 ), wherein the first flexure hinge axis (37) and the second flexure hinge axis (41) extend transverse to the second direction (y) in parallel to each other, allowing a thermal expansion of the recoater unit (21 ) in the second direction (y).

2. The recoater system ( 11 ) of claim 1 , wherein said at least one of the first mounting element (23a) and the second mounting element (23b) further comprises a third flexure hinge (43) defining a third flexure hinge axis (45) and a fourth flexure hinge (47) defining a fourth flexure hinge axis (49), wherein the first flexure hinge (35), the sec30 ond flexure hinge (39), the third flexure hinge (43) and the fourthatentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025flexure hinge (47) define a straight-line mechanism, in particular a Sarrus linkage or a Roberts linkage.

3. The recoater system (11) of claim 1 or 2, wherein the first flexure hinge axis (37) and the second flexure hinge axis (41 ) have a hinge 5 axis distance (A) to each other, wherein the hinge axis distance (A) is at least 5% of the track distance (D).

4. The recoater system (11) of any of the preceding claims, wherein the first flexure hinge (35) and the second flexure hinge (39) are part of a plurality of flexure hinges (35, 39, 43, 47) having parallel flexure 10 hinge axes (37, 41 , 45, 49), wherein the plurality of flexure hinges (35,39, 43, 47) is arranged in a series configuration, wherein a flexure hinge pivoting direction alternates between the flexure hinges (35, 39, 43, 47) along the series configuration.

5. The recoater system ( 11 ) of claim 4, wherein the series configuration follows a meandering path of structural integrity.

6. The recoater system (11) of any of the preceding claims, wherein the first flexure hinge (35) and the second flexure hinge (39) comprise a tapering of titanium-containing material.

7. The recoater system (11) of any of the preceding claims, wherein 20 said at least one of the first mounting element (23a) and the second mounting element (23b) comprises an inner mounting section (25), an outer mounting section (27) and at least one intermediary mounting section (29a, b,c), wherein the at least one intermediary mounting section (29a, b,c) has a first intermediary mounting section 25 end (31 ) being connected to the inner mounting section (25), and wherein the at least one intermediary mounting section (29a, b,c) has a second intermediary mounting section end (33) being connected to the outer mounting section (27), wherein the at least one atentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025intermediary mounting section (29a, b,c) extends essentially transverse to the second direction (y), wherein the first flexure hinge (35) is displaceable by a displacement distance in the second direction (y) relative to the second flexure hinge (39).5 8. The recoater system ( 11 ) of claim 7, wherein said at least one of the first mounting element (23a) and the second mounting element (23b) further comprises a third flexure hinge (43) defining a third flexure hinge axis (45) and a fourth flexure hinge (47) defining a fourth flexure hinge axis (49), wherein the at least one intermediary mount10 ing section (29a, b,c) is one of a first intermediary mounting section (29a) and a second intermediary mounting section (29b), wherein the second flexure hinge (39) and the third flexure hinge (43) connect the first intermediary mounting section (29a) and the second intermediary mounting section (29b) with each other, wherein the third flexure hinge (43) is displaceable in the second direction (y) relative to the fourth flexure hinge (35) by said displacement distance.

9. The recoater system (11) of claim 7 or 8, wherein the first intermediary mounting section (29a) and / or the second intermediary mount20 ing section (29b) extends in a third direction (z) transverse to both the first direction (x) and the second direction (y).

10. An additive manufacturing apparatus comprising a process chamber (1) and a recoater system (21) of any of the preceding claims for laying out a powder bed in the process chamber (1).25 11. The additive manufacturing apparatus of claim 10, wherein the first track (13) and the second track (15) of the recoater system (11) have a vertical distance (H) to the powder bed, wherein the vertical distance (H) is at least 5% of the track distance (D) of the recoatersystem (11).atentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 202512. The additive manufacturing apparatus of claim 10 or 11, wherein the powder bed has a powder bed width of at least 50 cm, wherein the track distance (D) of the recoater system (11) is larger than the powder bed width.5 13. The additive manufacturing apparatus of any of the claims 10 to 12, wherein the powder bed has a powder bed length of at least 50 cm, wherein the first track (13) and the second track (15) of the recoater system (11) have a track length (L) in the first direction (x) that is larger than the powder bed length.10atentanwdlte Hemmer Lindfeld Frese SLMP 3845 WO, 10 / 12 / 2025

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