ADDITIVE MANUFACTURING APPARATUS AND METHOD FOR OPERATING THE APPARATUS

Abstract

A process chamber housing for an additive manufacturing apparatus comprising a process chamber with a bottom, a ceiling, and sidewalls jointly enclosing a volume of the process chamber, with a gas inlet in a front wall and a gas outlet in a rear wall of the sidewalls. The gas inlet and outlet are positioned at opposite sides of an opening in the bottom and face each other, which allows for an improved removal of smoke out of the process chamber if the gas inlet has a width w.sub.i, the opening has a width w.sub.s, and the gas outlet has a width w.sub.0, such that at least one of the relations (i) w.sub.i≥w.sub.s±4 cm and w.sub.0≥w.sub.s±4 cm; (ii) w.sub.i≥w.sub.s and/or w.sub.0≥w.sub.s; and (iii) w.sub.i≥w.sub.s+1 cm and/or w.sub.0≥w.sub.s+1 cm is satisfied.

Claims

1. A process chamber housing for an additive manufacturing apparatus, the process chamber housing comprising a process chamber, wherein the process chamber housing has at least: a bottom of the process chamber, a ceiling of the process chamber, and side walls of the process chamber, jointly enclosing a volume of the process chamber, a gas inlet in a front wall of the side walls, the gas inlet configured to provide a gas flow into the process chamber, a gas outlet in a rear wall of the side walls, the gas outlet configured to release the gas flow out of the process chamber, a first recoater garage, confining a first storage volume of the first recoater garage dimensioned to house a recoater at a first recoater position, wherein at least one of the side walls of the process chamber has at least one housing door enabling access to the process chamber or is the housing door enabling said access , the housing door has a housing door opening and a housing door panel, the first storage volume of the first recoater garage is enclosed by at least one first garage wall and/or a first garage ceiling and/or a first garage bottom, the bottom of the process chamber has a support opening configured to receive a movable support for supporting a three-dimensional object, the gas inlet and the gas outlet are positioned at opposite sides of the support opening and face towards each other, thereby being configured to provide the gas flow in a main flow direction from the gas inlet over the opening to the gas outlet, at least a portion of the first garage wall and/or a first garage ceiling and/or a first garage bottom is formed by the door panel of the housing door.

2. The process chamber housing of claim 1, characterized in that the process chamber has a width w.sub.c(l, h), wherein the width w.sub.c(l, h) is measured perpendicularly to the main flow direction and is a function of (i) a distance l from a vertical plane that is defined by the gas inlet and (ii) a height h over a horizontal plane that is defined by the bottom of the process chamber, wherein w.sub.c(l, h)=c±0.15.Math.w.sub.max∀l∈ [l.sub.1, l.sub.2], wherein l.sub.1 is the distance of the opening from the vertical plane defined by the gas inlet, l.sub.2=l.sub.1+l.sub.s, l.sub.s is the extension of the opening in the main flow direction, w.sub.max=max(w.sub.c(l, h)), and c is a constant.

3. The process chamber housing of claim 2, characterized in that h ∈ [h.sub.min, h.sub.int], wherein h.sub.min≤0.1.Math.h.sub.max, h.sub.min≤h.sub.int≤0.25 h.sub.max and h.sub.max is the height of the process chamber measured from the bottom of the process chamber to the ceiling of the process chamber.

4. The process chamber housing of claim 1, characterized in that the first recoater garage is separated from the process chamber at least by a first movable portion of a first side wall of the side walls of the process chamber, the first movable portion of said first side wall is movably supported to be moved between a first closed position and an first open position, when in the first closed position, the first movable portion of said first side wall closes a first garage opening in the first sidewall and thereby separates the first recoater garage from the process chamber, and when in the first open position, the first movable portion of said first wall releases the first garage opening.

5. The process chamber housing of claim 1, further comprising: at least one recoater that is movably supported and configured to move in a forward direction from a first recoater position over the support opening to a second recoater position and in a backward direction from the second recoater position to the first recoater position, wherein said recoater has a front side facing in the forward direction and a rear side facing in the backward direction.

6. The process chamber housing of claim 5, characterized in that the front side of the recoater is the first movable portion of the first side wall, wherein the front side closes the garage opening, if the recoater is in the first recoater position and releases the first garage opening if the recoater is moved from the first recoater position towards the second recoater position.

7. The process chamber housing of claim 5, wherein the first recoater garage is separated from the process chamber at least by a first movable portion of a first side wall of the side walls of the process chamber, wherein the first movable portion of said first side wall is movably supported to be moved between a first closed position and an first open position, and characterized in that the first side wall, has a second movable portion that is movably supported to be moved between a second closed position and a second open position, wherein the second movable portion is in the second closed position if the recoater is in the second recoater position.

8. The process chamber housing of claim 7, characterized in that the second movable portion of the first side wall is biased towards the second closed position, and in that the recoater has an abutment configured to entrain the second movable portion of the first sidewall into the second open position if the recoater moves in the backward direction through the first garage opening to the first recoater position.

9. The process chamber housing of claim 5, characterized in that the process chamber housing further comprises a second recoater garage, the second recoater position is in the second recoater garage, the second recoater garage is separated from the process chamber at least by a first movable portion of a second side wall of the side walls, the first movable portion of said second side wall is movably supported to be moved between a third closed position and a third open position, when in the third closed position, the first movable portion of the second side wall closes a second garage opening in the second sidewall, and when in the third open position, the first movable portion of the second side wall releases the second garage opening.

10. The process chamber housing of claim 9, characterized in that the rear side of the recoater forms at least a first part of the first movable portion of the second side wall and closes the second garage opening when the recoater is in the second recoater position.

11. The process chamber housing of claim 9, characterized in that the second side wall has a second movable portion that is movably supported to be moved between a fourth closed position and a fourth open position, wherein the second movable portion of the second side wall is the fourth closed position if the recoater is in the first recoater position and when the second movable portion of the second side wall is in the fourth closed position, the second movable portion of the second side wall closes the second garage opening.

12. The process chamber housing of claim 4, characterized in that a normal drawn to the first side wall is within ±15° from a line that is perpendicular to the main flow direction.

13. The process chamber housing of claim 9, characterized in that a normal drawn to the second side wall is within ±15° from a line that is perpendicular to the main flow direction.

14. The process chamber housing of claims 1, characterized in that the gas inlet has a width w.sub.i, the support opening has a width w.sub.s, and the gas outlet has a width w.sub.o, the widths w.sub.i, w.sub.o and w.sub.s being measured perpendicularly to the main flow direction, and in that w.sub.i, w.sub.o and w.sub.s obey at least one of the following relations: w.sub.i≥w.sub.s±4 cm and w.sub.o≥w.sub.s±4 cm. w.sub.i≥w.sub.s and/or w.sub.o≥w.sub.s. w.sub.i≥w.sub.s+1 cm and/or w.sub.o≥w.sub.s+1 cm

15. The process chamber housing of claim 14, characterized in that w.sub.s≤w.sub.c−d.sub.m, wherein 1 cm≤d.sub.m≤30 cm.

16. The process chamber housing of claims 14, characterized in that w.sub.c≥w.sub.i≥w.sub.c−5 cm.

17. The process chamber housing of claim 1, characterized in that at least a portion of the rear wall above the gas outlet is inclined toward the gas inlet.

18. The process chamber housing of claim 1, characterized in that, the door panel has a fifth closed position and/or orientation and a fifth open position and/or orientation, wherein the door panel closes the door opening when in the fifth closed position and/or orientation and releases the door opening when in the fifth open position and/or orientation.

19. The process chamber housing of claim 9, wherein the door panel has a fifth close position and a fifth open position, and characterized in that the first movable portion of at least one of the first side wall and r the second side wall, separating a corresponding one from the first recoater garage and the second recoater garage from the process chamber, is movably attached to the door panel and is configured to move with the door panel when the door panel is moved from the fifth open position to the fifth closed position or from the fifth closed position to the fifth open position.

20. The process chamber housing of claim 1, wherein the process chamber housing further comprises a second recoater garage, and characterized in that the second recoater garage confines a second storage volume.

21. The process chamber housing of claim 20, characterized in that at least a portion of the first storage volume and/or the second storage volume is confined by at least a portion of at least one of the side walls of the process chamber.

22. The process chamber housing of claim 20, characterized in that at least a portion of the first storage volume and/or the second storage volume is confined by a part of the housing door panel.

23. An additive manufacturing apparatus for manufacturing three-dimensional objects from a raw material, said apparatus comprising the process chamber housing of claim 1 and a radiation source configured to selectively adhere moieties of raw material (i) to a support unit that is repositionably located in and/or below the support opening and/or (ii) to previously adhered moieties of raw material.

24. A process chamber housing for an additive manufacturing apparatus, the process chamber housing comprising a process chamber, wherein the process chamber housing has at least: a bottom, a ceiling, and side walls, jointly enclosing a volume of the process chamber, a gas inlet in a front wall of the side walls, said gas inlet configured to provide a gas flow into the process chamber, a gas outlet in a rear wall of the side walls, said gas outlet configured to release the gas flow out of the process chamber, a first recoater garage confining a first storage volume, the first storage volume dimensioned to house a recoater at a first recoater position, a second recoater garage confining a second storage volume, the second storage volume configured to house the recoater at a second recoater position, wherein the bottom has an opening configured to receive a movable support unit that is configured to support a three-dimensional object, the gas inlet and the gas outlet are positioned at opposite sides of the opening such as to face each other, thereby being configured to provide the gas flow in a main flow direction from the gas inlet over the opening to the gas outlet, the first recoater garage and the second recoater garage are at opposite sides of the opening.

25. A process chamber housing for an additive manufacturing apparatus, the process chamber housing comprising a process chamber, wherein the process chamber housing has at least: a bottom, a ceiling, and side walls, jointly enclosing a volume of the process chamber, a gas inlet in a front wall of the side walls, said gas inlet configured to provide a gas flow into the process chamber, a gas outlet in a rear wall of the side walls, said gas outlet configured to release the gas flow out of the process chamber, a first recoater garage confining a first storage volume, the first storage volume configured to house a recoater at a first recoater position, a second recoater garage confining a second storage volume, the second storage volume configured to house the recoater at a second recoater position, wherein the bottom has an opening configured to receive a movable support for supporting a three dimensional object, the gas inlet and the gas outlet are positioned at opposite sides of the opening and both face towards each other, thereby being configured to provide the gas flow in a main flow direction from the gas inlet over the opening to the gas outlet, the first recoater garage is separated from the process chamber at least by a first movable portion of a first side wall of the side walls, the first movable portion of said first side wall is movably supported to be moved between a first closed position and a first open position, when in the first closed position, the first movable portion of the first side wall closes a first garage opening in the first sidewall and thereby separates the first recoater garage from the process chamber, and when in the first open position, the first movable portion of the first side wall releases the first garage opening, the second recoater garage is separated from the process chamber at least by a first movable portion of a second side wall of the side walls, the first movable portion of the second side wall is movably supported to be moved between a second closed position and a second open position, when in the second closed position, the first movable portion of the second side wall closes a second garage opening in the second sidewall, and when in the second open position, the first movable portion of the second side wall releases the second garage opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0070] In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings.

[0071] FIG. 1 is a simplified sketch of a sectional view of an embodiment of a process chamber housing.

[0072] FIG. 2 is another simplified sketch of an embodiment of a process chamber housing.

[0073] FIG. 3 presents schematically a sectional view of an embodiment of a process chamber housing,

[0074] FIG. 4 shows a simplified sketch of a sectional view of the embodiment of the process chamber housing of FIG. 3,

[0075] FIG. 5 shows a simplified sketch of a related implementation of the process chamber housing.

[0076] FIG. 6 shows a sectional view of a detail of a first garage without a recoater.

[0077] FIG. 7 shows a sectional view of a detail of the embodiment of the garage of

[0078] FIG. 6 with a recoater.

[0079] FIG. 8 is a sectional view of a detail of an embodiment of the first garage without a recoater.

[0080] FIG. 9 shows a sectional view of a detail of the garage of FIG. 8 with a recoater.

[0081] FIG. 10 is a sectional view of a detail of an embodiment of the garage similar to the one of FIGS. 8 and 9 with a recoater.

[0082] Generally, the drawings are not to scale. Like elements and components are referred to by like labels and numerals. For the simplicity of illustrations, not all elements and components depicted and labeled in one drawing are necessarily labels in another drawing even if these elements and components appear in such other drawing.

[0083] While various modifications and alternative forms, of implementation of the idea of the invention are within the scope of the invention, specific embodiments thereof are shown by way of example in the drawings and are described below in detail. It should be understood, however, that the drawings and related detailed description are not intended to limit the implementation of the idea of the invention to the particular form disclosed in this application, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION

[0084] FIG. 1 shows a simplified sketch of a process chamber housing 1 as viewed at a position approximately corresponding to the height h.sub.1as shown in FIG. 2. FIG. 2 is a perspective side view of a process chamber housing 1 of FIG. 1, but in which perspective side view a second side wall 12 (expressly shown in FIG. 1) has been removed. Together, FIGS. 1 and 2 illustrate an embodiment of the process chamber housing. The process chamber housing 1 has a first sidewall 11 and a second side wall 12 being opposed to each other and having a length l.sub.max. Further, the process chamber 5 (FIGS. 1 and 2) is delimited by a front wall 21 and by a rear wall 22. In this example, the contour of each of the four walls 11, 12, 21 and 22 are in a plane, at least with respect to the side walls 11, 12 this is a preferred example, other shapes are not excluded. A bottom 9 with a support opening 91 for an optional support 8 delimits the process chamber 5 downwards and a ceiling 10 (see FIG. 2) upwards. The first sidewall 11 is movably attached, for example hinged, to a support structure, e.g. to one of its neighbouring walls 21 or 22. Hence, the first sidewall is a door panel of the process chamber housing 1, enabling access to the process chamber 5. In an alternative example, the door panel may be formed by a portion of a side wall 11. The latter may be easier to manufacture, but provides a smaller door opening, i.e. accessibility of the process chamber 5 is reduced compared to the depicted option.

[0085] As can be seen in FIG. 1 and FIG. 2, the front wall 21 has a gas inlet 6 configured to provide a main gas flow in a main-flow direction 2 (indicated by arrow 2) towards a gas outlet 7 in the rear wall 12. In the structure illustrated in FIGS. 1 and 2, the gas inlet 6 is a porous material extending over the entire surface of the front wall, however it should be noted that this is only a preferred example of a gas inlet 6. Other gas inlets configurations can be used as well. In particular, the gas inlet may cover or form only at least one sub portion of the front wall. For example, a particular gas inlet can be formed by a one or more slots the front wall. In addition, some examples may also include gas inlet openings in the ceiling 10 of the process chamber 5 for providing a support gas flow. The distance between the front wall and the rear wall defines the length l.sub.max of the process chamber (see FIG. 1). The distance from the front wall 21 is thus measured parallel to the main-flow direction 2 as indicated by the axis I, having l.sub.o=0 at the vertical plane through the bottom of the front wall 21. The gas inlet 6 and the gas outlet 7 each have a width w.sub.i and w.sub.o, respectively, being measured at least essentially perpendicular to the main-flow direction 2 (see FIG. 1).

[0086] In these examples, the distance between the first and second side walls 11, 12 is the free width w.sub.c(l, h) enabling an inert gas flow being indicated in FIG. 1 by small parallel arrows leaving the gas inlet 6 and entering the gas outlet 7. Thus, the gas flow transports smoke, that is generated during fusing of powder on top of the support 8, towards the gas outlet 7 in the rear wall 22. In general, w.sub.c is a function of the distance l from the front wall 21 and the height h over the bottom (see FIG. 2), i.e. w.sub.c=w.sub.c(l, h). Notably, in the example shown in FIGS. 1, 2, 3, and 4, the free width is substantially constant (neglecting minor gaps in the side walls 11, 12), i.e. w.sub.c(l, h)=c=w.sub.max, ∀l∈]l.sub.0, l.sub.max[, at a given height h. As explained above, this is a preferred example, in practice small variations Δ.sub.w can be accepted, i.e. w.sub.c(l, h)=c±Δ.sub.w.Math.w.sub.max∀l ∈[l.sub.1, l.sub.2].

[0087] Due to the at least essentially constant free width w.sub.c(l, h) of the process chamber, the distances d.sub.m/2 between the support opening 91 and first and second side walls 11, 12 can be rather small. It should be noted that in these preferred examples, the distances d.sub.m/2 are not drawn to scale but have been enlarged.

[0088] Each side wall 11, 12 has first and second movable portions 111, 112, 121 and 122, respectively, wherein in the sketch of FIG. 1 only the first side wall's first movable portion 111 and the second side wall's first and second movable portions 122 are shown, indicated as surfaces. The remaining movable portions 112 and 121 are shown in FIGS. 3 and 4.

[0089] FIG. 3 and FIG. 4 show simplified cross sectional views, of the a process chamber housing 1 very similar to the process chamber housing of FIG. 1 and FIG. 2, wherein the section plane is at least essentially perpendicular to the flow direction 2 as depicted in FIG. 1 and somewhere in between of l.sub.1 and l.sub.2, e.g. approximately at the planes III and IV being indicated in FIG. 1. Thus, the description of FIG. 1 and FIG. 2 can be read on FIG. 3 and FIG. 4 as well.

[0090] As shown in FIG. 1, FIG. 3 and FIG. 4, the process chamber housing includes a recoater 50 having a raw material reservoir 51. In FIG. 1 and FIG. 3, the recoater 50 is shown in an initial position, as well referred to herein as the recoater's first position. In this first recoater position, the recoater 50 is positioned in an optional first recoater garage 30. The first recoater garage 50 is separated from the process chamber 5 by a first movable portion 111 of the first sidewall 11. Thus, the first movable portion 111 of the first sidewall 11 is shown in the first sidewall's first movable portion's closed position, essentially closing the first garage opening in a static portion of the first sidewall 11 (see FIGS. 1 and 3). A second movable portion 112 of the first sidewall 11 may be stowed in the first garage 30 at the rear side 121 of the recoater 50 and thus in the first sidewall's second movable portion's open position. Preferably, the second movable portion 112 of the first sidewall 11 is biased toward its closed position, being shown in FIG. 4.

[0091] Still in reference to FIG. 3, the process chamber housing 1 further includes a second recoater garage 40, being empty in FIG. 3. The second recoater garage 40 may as well be separated from the process chamber 5 by a movable portion 122 of the second side wall 12. We will refer to this movable portion 122 as the second sidewall's second movable portion. The second side wall 12 has as well a first movable portion 121, which is integrally formed by the rear side of the recoater 50 and is shown in FIG. 3 in its open position, as it is stowed in the first garage 30. As indicated by sketched hinges 128, the entire side wall 12 is optionally movably attached to a support structure of the process chamber housing 1. The side wall 12, or at least a portion thereof thus forms a door panel 129. Further, portions of the confinement of the second recoater garage 40 are formed by the door panel 129 as well, and hence pivot with the door panel 129, if it is opened to enable access to the process chamber 5. When all garage doors are closed, the confinement is complete to avoid inert gas to leak through the garage.

[0092] After the upper layer of the raw material 99 has been partially fused to a part of a workpiece 4, the support 8 is lowered by the thickness of a layer of raw material 99. Next, the recoater 50 is moved from its first position to its second position, i.e. into the second garage 40, thereby applying a new layer of raw material into the support opening 91. Whereas FIG. 3 shows the recoater 50 in its first position, FIG. 4 shows the recoater 50 after having moved over the support opening 91 into its second position.

[0093] As can be seen in FIG. 4, the first sidewall's second movable portion 112 is shifted horizontally into the first garage opening into the first sidewall's second movable portion's 112 closed position. The first sidewall's second movable portion 112 is horizontally movable, e.g. supported by a linear bearing enabling an at least essentially horizontal movement of the first sidewall's second movable portion 112 from its open position (FIG. 3) into its closed position (FIG. 4) and back into its open position (cf. FIGS. 6 and 7). The first sidewall's second movable portion 112 is biased into its closed position. Thus, as soon as the recoater 50 is moved forward towards the recoater's second position, the first sidewall's second movable portion 112 follows the recoater 50 until the first sidewall's second movable portion 112 reaches it closed position.

[0094] Once the recoater 50 approaches the second garage opening, it abuts the second side wall's second movable portion 122, thereby moving second movable portion 122 into its closed position (by moving on into the recoater's second position) as shown in FIG. 4. As shown in this example, it is advantageous if the second side wall's second movable portion is hinged relative to static portion of the second side wall 12, wherein the pivot axis is at least essentially parallel to the main flow direction 2 and above the recoater's top. Thereby, the raw material reservoir 51 of the recoater 50 is closed by the second side wall's second movable part. Superfluous raw material 99 may fall into a tray 45 (cf. FIGS. 8 and 9) in the second garage's bottom.

[0095] As shown in FIG. 4, the second garage opening may be closed by the first movable portion 121 of the second side wall 12. The first movable portion 121 of the second side wall 12 may be integrally formed or be attached to the rear side of the recoater 50. Another portion of the second garage opening may be closed by a third movable portion 123 of the second side wall 12, being moved into the garage opening and thus into its respective closed position, when the second movable portion 122 is moved into its open position. In this optional example, the third movable portion 123 is provided by a free leg being attached to an end of the second movable portion 122 of the second side wall. Thereby gaps are minimized. Alternatively, the second movable portion 122 could be movably supported differently, e.g. by at least one linear bearing as shown for the second movable portion 112 of the first side wall 11. This has the advantage of less different parts but increases the footprint of the process chamber housing 1.

[0096] Once the newly added layer of raw material has been at least partially fused to the workpiece 4 and the support has been lowered, the recoater 50 maybe moved backwards into its first position, thereby applying a next layer of raw material 99 onto the support. While the recoater 50 passes the second garage opening, the second movable portion 122 of the first second wall 12 enters its closed position. For example, second movable portion 122 of the second side wall 12 may simply pivot, e.g. by gravity into its closed position. As soon as the recoater 50 reaches the first garage opening, it retracts the second movable portion 112 of the first side wall into its open position, while the first movable portion 111 of the first sidewall 11 closes the first garage opening (as shown in FIG. 3). The optional raw material dispenser 3 being positioned above the recoater 50 may replenish the recoater's raw material reservoir 51 and the cycle may be repeated until the workpiece 4 is finished.

[0097] The process chamber housing 1 in FIG. 5 is very similar to the process chamber housing 1 in FIG. 2. (That is, the description of FIG. 2 can be applied to FIG. 5 as well and FIG. 2 could be replaced by FIG. 5, i.e. FIG. 5 has to be read in the context of FIGS. 1, 3 and 4, as well.) Different from the example of FIG. 2, the rear wall 22 of the process chamber housing 1 has an optional inclined portion 225. The optional inclined portion 225 is a guide plate 225 being positioned above the outlet opening 7. The guide plate delimits the process chamber in the flow direction 2 and is thus a part of the rear wall 22. The guide plate 225 connects a non-inclined portion of the rear wall 22 with the ceiling 10. As apparent from FIG. 5, the inclined portion 225 (i.e. the guide plate) is inclined towards the front wall 21. In other words, with increasing height, the distance between the rear wall 22 and the front wall decreases. In operation the inclined portion 225 thus provides for an (inclined) downdraft a without dead volume. Further, the downdraft (see dashed lines) removes up drafting smoke, which cannot be entirely avoided due to the heat being released by the fusion process.

[0098] FIG. 6 shows a sectional view of a detail of an empty garage 30, i.e. of a first garage without recoater 50, which could be parked and refilled in the garage 30. The first garage 30 has a space being delimited towards the process chamber by a first sidewall 11 of the process chamber 5 (cf. FIGS. 1 to 5). The bottom plate, forming the bottom 9 of the process chamber 5 as shown in FIGS. 1 to 5 extends into the first garage 30, providing a garage bottom. In the depicted preferred example, the garage bottom has raw material fall through removal tray 35, removal tray 35 for short, preventing the accumulation of raw material in the first garage 30. Above the removal tray 35 is an outlet 98 of a dispenser 3 (see FIGS. 2 and 5), as well referred to as raw material dispenser outlet 98. In the depicted preferred example, the first position of the recoater 50 is in between of the removal tray 35 and the raw material dispenser outlet 98, as shown in FIG. 7.

[0099] A static portion 114 of the first sidewall 11 defines the first garage opening. The first garage opening may be closed by a first movable portion 111 and/or by a second movable portion 112 of the first sidewall. In FIG. 6, the first garage opening is shown closed by the optional second movable portion 112 of the first sidewall 11. The second movable portion 112 of the first side wall 12 may be movably supported enabling the second movable portion 112 to be moved from its closed position being shown in FIG. 6 into an open position as shown in FIG. 7. In a preferred example, the second movable portion 112 of the first side wall 11 is supported by a linear bearing, enabling a horizontal movement of the second movable portion 112 towards a rear end 32 of the first garage 30 as shown in FIG. 7. As usual, the rear end 32 is the end opposite of the garage opening.

[0100] FIG. 7 shows a sectional view of a detail of the first garage of FIG. 6 after a recoater 50 has been parked in the first garage, i.e. in the recoater's first position. As can be seen, the front surface of the recoater 50 may close the first garage opening and may thus provide the first movable portion 111 of the first side wall 11. The rear surface of the recoater 50 provides an abutment configured to entrain the second movable portion 112 of the first sidewall, if the recoater 50 is moved into the first garage 30. In a preferred example, the second movable portion of the first sidewall 11 is biased, e.g. spring loaded, towards its closed position. Alternatively or additionally, the second movable portion includes a first first coupling portion configured to releasably couple mechanically with a first second coupling, wherein the two coupling portions are configured to transmit a pulling force from the recoater 50 to the second movable portion 112. In this example, the movement of the recoater out of the first garage entrains the second movable portion into its closed position. In the closed position the coupling opens and the recoater may continue its moment towards the second side wall 12. The coupling may be a positive locking and and/or magnetic coupling. Thus, in the depicted preferred example, the first garage opening is only open, while the recoater 50 passes first garage opening. Perturbations of the inert gas flow (cf. FIGS. 1 to 5) by the first garage opening are thus limited to a minimum.

[0101] While the recoater 50 is parked in the first garage 30 in the first recoater position it may be refilled with raw material 99. A second garage 40 is at the opposite side of the process chamber 5, as shown in FIGS. 8 and 9. Similarly to the first garage 30, the second garage 40 has a space being delimited towards the process chamber 5 by a second sidewall 12 of the process chamber 5 (cf. FIGS. 1, 3 to 5). The bottom plate, forming the bottom 9 of the process chamber 5 as shown in FIGS. 1 to 5 may extend as well into the second garage 40, providing a garage bottom. The second garage bottom has second raw material fall through removal tray 45, removal tray 45 for short, preventing the accumulation of raw material in the second garage 30. A raw material dispenser 3 with a raw material dispenser outlet 98 could be realized above the second garage 40, as well, but is preferably omitted as shown.

[0102] A static portion 124 of the first sidewall 12 defines a second garage opening. The second garage opening may be closed by a first movable portion 121 and/or by a second movable portion 122 of the second sidewall 12. In FIG. 8, the second garage opening is shown closed by the optional second movable portion 122 of the second side wall 12. The second movable portion 122 of the second side wall 22 is movably supported enabling the second movable portion 122 to be moved from its closed position being shown in FIG. 8 into an open position as shown in FIG. 9. Thus, in this example, the second movable portion 122 is pivotably supported relative to the garage opening defining portion 124 of the second side wall 12. Moving the recoater 50 further towards the rear end 43 of the second garage 40 may position the recoater right above the second garage's removal tray 45, which is in this example the recoater's second position. In this second recoater position, the second movable portion 122 of the second side wall 12 pivots back into its closed position (FIG. 9). This closed position is at least essentially flush with the second garage opening defining portion 124 of the second side wall 12 and thus turbulences or other perturbations of the inert gas flow are minimized. Alternatively, the second recoater position of the recoater 50 could be shifted slightly to the process chamber 5, wherein the backward facing surface 122 (indicated by a dashed ‘tick line’) of the recoater 50 provides a first movable portion 121 of the second side wall 12, being at least essentially flush with the second side wall's second garage opening defining portion 124 (see FIG. 10). In this case, the second removal tray 45 is preferably shifted as well, so that it is under the recoater 50 in its second end position.

[0103] As can be seen in FIGS. 8 to 10, above the second garage opening defining portion 124 of the second wall is a movable door 129, i.e. a door panel 129, forming a part of the second wall 12 and enabling to access to process chamber 5. In FIGS. 1, 2, 3, 4, and 5 this door has been omitted (not indicated) for simplificy of illustration and is at least essentially flush with neighbouring portions of the second side wall 12.

[0104] In the Figures, portions of walls are indicated by ‘ticks’ referring to the process chamber facing surface of the respective portion.

[0105] It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide a process chamber housing for an additive manufacturing apparatus, an additive manufacturing apparatus and a method for operating these. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

[0106] For the purposes of this disclosure and the appended claims, the use of the terms “substantially”, “approximately”, “about”, “essentially” and similar terms in reference to a descriptor of a value, element, property, or characteristic at hand is intended to emphasize that the value, element, property, or characteristic referred to, while not necessarily being exactly as stated, would nevertheless be considered, for practical purposes, as stated by a person of skill in the art. These terms, as applied to a specified characteristic or quality descriptor means “mostly”, “mainly”, “considerably”, “by and large”, “to great or significant extent”, “largely but not necessarily wholly the same” such as to reasonably denote language of approximation and describe the specified characteristic or descriptor so that its scope would be understood by a person of ordinary skill in the art. In one specific case, the terms “approximately”, “substantially”, “essentially” and “about”, when used in reference to a numerical value, may represent a range of plus or minus 20% with respect to the specified value, more preferably plus or minus 10%, even more preferably plus or minus 5%, most preferably plus or minus 2% with respect to the specified value. As a non-limiting example, two values being “substantially equal” to one another may imply that the difference between the two values may be within the range of +/−20% of the value itself, preferably within the +/−10% range of the value itself, more preferably within the range of +/−5% of the value itself, and even more preferably within the range of +/−2% or less of the value itself.

LIST OF REFERENCE NUMERALS

[0107] 1 process chamber housing

[0108] 2 gas flow direction, longitudinal axis

[0109] 3 raw material dispenser

[0110] 4 workpiece/adhered moieties of raw material

[0111] 5 process chamber

[0112] 6 gas inlet

[0113] 7 gas outlet

[0114] 8 support

[0115] 9 bottom

[0116] 91 support opening in bottom 9, configured to receive support 8

[0117] 10 ceiling

[0118] 11 first sidewall

[0119] 111 first movable portion of first sidewall

[0120] 112 second movable portion of first sidewall

[0121] 114 first garage opening defining portion of first sidewall

[0122] 119 housing door (part of first wall 11 or entire first wall 11)/door panel

[0123] 12 second sidewall

[0124] 121 first movable portion of second sidewall

[0125] 122 second movable portion of second sidewall

[0126] 123 second movable portion of second sidewall

[0127] 124 second garage opening defining portion of second sidewall

[0128] 128 hinge

[0129] 129 housing door (part of second wall 12 or entire second wall 12)/door panel

[0130] 21 front wall

[0131] 22 rear wall

[0132] 225 guide plate

[0133] 30 first garage (optional)

[0134] 32 rear end of first garage

[0135] 35 raw material removal duct

[0136] 40 second garage (optional)

[0137] 42 rear end of second garage

[0138] 45 raw material removal duct

[0139] 50 recoater

[0140] 51 recoater's reservoir

[0141] 80 beam generating unit/laser unit

[0142] 98 raw material dispenser outlet

[0143] 99 raw material/powder

[0144] l distance from vertical plane through the bottom of the front wall

[0145] w.sub.s width of the opening and/or of the support

[0146] w.sub.c(l,h) width of the chamber

[0147] w.sub.i width of the gas inlet

[0148] w.sub.o width of the gas outlet