MANUFACTURING DEVICE AND METHOD FOR ADDITIVE MANUFACTURING WITH MOVABLE GAS OUTLET

Abstract

Disclosed is a manufacturing device for the additive manufacturing of a three-dimensional object, wherein the object is manufactured by applying a building material layer by layer and selective solidification of the building material, at points in each layer which are assigned in this layer to the cross-section of the object. The points are scanned with at least one exposure area. The movable gas outlet is assigned during operation to a reference process point and/or a target flow supply zone of the movable gas outlet assigned to the reference process point for the flow supply with the process gas and/or the target ventilation zone of the movable gas outlet.

Claims

1. A manufacturing device for the additive manufacturing of a three-dimensional object, wherein the object is manufactured by applying a building material layer by layer and selective solidification of the building material at points in each layer which are assigned in this layer to the cross-section of the object, whereby the points are scanned with at least one exposure area, with a building container for receiving the building material, with a process chamber above the building container, with a building field between the building container and the process chamber, with at least one gas inlet for introducing process gas into the process chamber, with at least one gas outlet for discharging the process gas from the process chamber, wherein the at least one gas outlet can be moved solely outside the building field.

2. The manufacturing device according to claim 1, wherein the outlet opening of the at least one gas outlet can be moved in at most one degree of freedom in translation and/or in at most one degree of freedom in rotation relative to the building field.

3. The manufacturing device according to claim 1, characterised in that the outlet opening is arranged in a wall of the process chamber and/or adjacent to or close to an edge of the building field.

4. The manufacturing device according to claim 1, characterised in that the outlet opening is arranged essentially horizontally displaceable.

5. The manufacturing device according to claim 1, characterised in that the outlet opening is constituted on a movable nozzle.

6. The manufacturing device according to claim 1, characterised in that the outlet opening is implemented by a slider in the wall.

7. The manufacturing device according to any one of the above claims 1, characterised in that the outlet opening has a variable opening cross-section.

8. The manufacturing device according to claim 1, characterised in that at least two outlet openings are arranged one above the other on the same side of the process chamber and/or that at least two outlet openings are arranged on the adjacent and/or opposite sides of the process chamber.

9. The manufacturing device according to claim 1, characterised in that the travel path or the opening of the gas outlet has at least the length of a building field side, along which it acts.

10. The manufacturing device according to claim 1, characterised by at least one outlet opening per activatable radiation beam bundle of the manufacturing device.

11. The manufacturing device according to claim 1, characterised in that the outlet opening is movable in a lower half of a clear height of the process chamber.

12. A method for producing a three-dimensional object by means of an additive manufacturing device with a gas inlet and a movable gas outlet for the process gas in accordance with claim 1, wherein the object is manufactured by the application of a building material layer upon layer and selective solidification of the building material at points in each layer which are assigned in this layer to the cross-section of the object, in that the points are scanned with at least one exposure area, wherein the movable gas outlet is assigned during operation to a reference process point and/or a target ventilation zone of the movable gas outlet assigned to the reference process point.

13. The method according to claim 12, characterised in that the control of the movement of an outlet opening of the gas outlet takes place dependent on a detected local impurity concentration in the process chamber above the building field.

14. The method according to claim 12, wherein the gas inlet is movable, characterised in that the orientation of an opening of the gas inlet is selected/adjusted dependent on a position or orientation of the outlet opening of the gas outlet.

15. The method according to claim 14, characterised in that an angle, which the opening planes of the gas inlet and of the gas outlet enclose with one another, does not exceed a predefined angle threshold value.

Description

[0046] The principle of the invention is explained in greater detail below by way of example with the aid of a drawing. In the figures:

[0047] FIG. 1: shows a diagrammatic view, represented partially in cross-section, of a device for the additive manufacturing of manufacturing products according to the prior art,

[0048] FIG. 2: shows a diagrammatic partial cross-sectional view of a device according to an embodiment of the invention with a swivellable gas outlet in the plane corresponding to intersecting line D-D according to FIG. 1,

[0049] FIG. 3: shows a diagrammatic cross-sectional view of the device according to an alternative embodiment of the invention with a swivellable gas outlet,

[0050] FIG. 4: shows a diagrammatic cross-sectional view with two swivellable gas outlets according to a further embodiment of the invention,

[0051] FIG. 5: shows a diagrammatic cross-sectional view with two embodiments of a movable gas outlet according to a further embodiment of the invention,

[0052] FIG. 6: shows a diagrammatic cross-sectional view with an alternative movable gas outlet according to a further embodiment of the invention,

[0053] FIG. 7: shows a diagrammatic cross-sectional view with an alternative movable gas outlet according to a further embodiment of the invention,

[0054] FIG. 8: shows a view of the process chamber wall according to intersecting line VIII-VIII in FIG. 7,

[0055] FIG. 9: shows a further such view with two gas outlets one above the other,

[0056] FIG. 10: shows an alternative view to FIG. 8, and

[0057] FIG. 11: shows an alternative view to FIG. 9 with two gas outlets one above the other.

[0058] The device represented diagrammatically in FIG. 1 is a laser sintering or laser fusion device a1 known per se. For the build-up of an object a2, it contains a cuboid process chamber a3 with a plane-surfaced chamber wall a4. An upwardly open building container a5 with a wall a6 is arranged in process chamber a3. A working plane a7 is defined by the upper opening of building container a5, wherein the area of working plane a7 lying inside the opening, which can be used for building up object a2, is referred to as building field a8.

[0059] Arranged in container a5 is a carrier a10 movable in a vertical direction V, to which a base plate all is fitted, which terminates building container a5 downwards and thus forms the bottom thereof. Base plate all can be a plate formed separated from carrier a10, which plate is attached to carrier a10, or it can be formed integrally with carrier a10. Depending on the powder used and the process, a building platform a12 can also be fitted on base plate all, on which platform object a2 is built up. Object a2 can however also be built up on base all itself, which then serves as a building platform. In FIG. 1, object a2 to be formed in building container a5 on building platform a12 is represented below working plane a7 in an intermediate state with a plurality of solidified layers, surrounded by building material a13 which has remained unsolidified.

[0060] Laser sintering device a1 also contains a storage container a14 for a powder-like building material a15 which can be solidified by electromagnetic radiation and a coater a16 movable in a horizontal direction H for applying building material a15 onto building field a8.

[0061] Laser sintering device a1 also contains an illumination device a20 with a laser a21, which generates a laser beam a22, which is deflected by deflection device a23 and focused onto working plane a7 by a focusing device a24 via a coupling window a25, which is fitted at the upper side of process chamber a3 in its wall a4.

[0062] Laser sintering device a1 also contains a control unit a29, via which the individual components of device a1 are controlled in a coordinated manner to perform the building process. Control unit a29 can contain CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separated from the device on a storage medium, from which it can be loaded into the device, in particular into control unit a29.

[0063] During operation, carrier a10 is first lowered, for the application of a powder layer, by a height which corresponds to the desired layer thickness. A layer of powder-like building material a15 is then applied by moving coater a16 over working plane a7. For safety, coater a16 pushes a somewhat larger quantity of building material a15 in front of it than is required for the build-up of the layer. The intentional excess of building material a15 is pushed by coater a16 into an overflow container a18. An overflow container a18 is arranged in each case on both sides of building container a5. The application of powder-like building material a15 takes place at least over the entire cross-section of object a2 to be manufactured, preferably over entire building field a8, i.e. the area of working plane a7, which can be lowered by a vertical movement of carrier a10.

[0064] The cross-section of object a2 to be manufactured is then scanned by laser beam a22 with a radiation exposure area, so that powder-like building material a15 is solidified at process points which correspond to the cross-section of object a2 to be manufactured. These steps are repeated until such time as object a2 is completed and can be removed from building container a5.

[0065] To generate a preferably laminar gas flow a34 in process chamber a3, laser sintering device a1 also contains a gas supply channel a32, a gas inlet nozzle a30, a gas extraction nozzle a31 and a gas discharge channel a33. Gas flow a34 moves away over building field a8. The gas supply and discharge can also be controlled by control unit a29. The gas extracted from process chamber a3 can be led to a filtering device (not shown), and the filtered gas can be fed via gas supply channel a32 back to process chamber a3, as a resuit of which an air circulation system with a closed gas circuit is formed. Instead of just one gas inlet nozzle a30 and one gas extraction nozzle a31, a plurality of nozzles can also be provided in each case. FIG. 2 shows a diagrammatic partial cross-sectional view onto a device according to the invention with a swivellable gas outlet 32 in a plane corresponding to intersecting line D-D according to FIG. 1. FIG. 2 shows a plan view of cuboid process chamber 3, which is surrounded by plane-surfaced, vertically projecting chamber wall 4. Rectangular building field 8 lies inside process chamber 3.

[0066] Chamber wall 4 has a rectangular opening 41 extending essentially horizontally, which lies on a side of building field 8 facing a building field edge 81. It lies at a height just above building field 8 and has a width which corresponds approximately to the length of building field edge 81. A gas discharge channel 33 of gas outlet 32 projects through opening 41, said gas discharge channel being horizontally swivellable in sections. It is composed of a fixed section 35 and a swivellable tubular section 36, which are fluidically connected to each other at a hinge 37 and convey a gas flow 34. At an end of swivellable section 36 at the building field side lying opposite hinge 37 is an outlet opening 31. Its extension plane is orthogonal to building field 8 in every position of swivellable section 36.

[0067] The position of hinge 37 and the length of swivellable section 36 are matched to one another in such a way that outlet opening 31 at building field edge 81 can be swivelled over its entire length, without passing over building field 8 itself even only partially. Swivellable section 36 thus prevents any action of the laser beam (not represented) on building field 8. To cover opening 41, a blind (not represented) can be fitted to swivellable section 36, which moves with the latter and covers opening 41 optionally at both sides and slides in front of or behind chamber wall 4 on the other side of opening 41.

[0068] FIG. 3 shows a comparable diagrammatic cross-sectional view of the device with an alternative partially swivellable gas discharge channel 33; its horizontal swivellable tubular section 36 can be folded into a niche 42 in chamber wall 4. Niche 42 has a depth in the direction of the plane of building field 8 which corresponds at least to the diameter of tubular section 36. Its hinge 37 also lies in niche 42 and connects it to a fixed section (not represented) of gas discharge channel 33. The fixed section can be connected fluidically at the hinge vertically, horizontally or at another angle. At the end lying opposite hinge 37, swivellable section 36 comprises an outlet opening 31 of gas outlet 32.

[0069] The swivelling area of swivellable section 36 makes it possible outlet opening 31 to move away from building field edge 81, without projecting over building field 8 itself. Its horizontal swivelling movement does not therefore extend over building field edge 81 into building field 8 or into the volume above building field 8. The volume above building field 8 is thus demarcated from the remaining volume of process chamber 3 or a3, in that a perpendicular is dropped onto building field edge 81. During action of the coater (not represented), e.g. during a coating movement over building field 8, swivellable section 36 folds into niche 42, in order not to impair its working space between building field edge 81 and chamber wall 4 during its operation.

[0070] FIG. 4 shows in a further diagrammatic cross-sectional view two partially swivellable gas discharge channels 33a, 33b, which are designed in principle comparable to gas discharge channel 33 of FIG. 3. Their respective hinges 37a, 37b as pivoting points of their swivellable sections 36a, 36b also lie in a niche 42 in chamber wall 4, the dimensions of which correspond to those according to FIG. 3. Its outlet openings 31a, 31b can in each case be swivelled in quarter-circle arcs v between niche 42 and an edge 81 of building field 8 facing them. They reach their smallest distance from building field edge 81 in each case at the left-hand and right-hand ends of building field edge 81. With a deflection on the geometrical centre of quarter-circle arc v or at 45° with respect to the position folded completely into niche 42, both gas discharge channels 33a, 33b can simultaneously act on a central area of building field edge 81, so that they also ensure a suitable gas flow 34 there (see FIG. 1). The two swivellable sections 36a, 36b can also be folded completely into niche 42 and for the same purpose and using the same advantages as explained in FIG. 3.

[0071] FIG. 5 shows a further diagrammatic cross-sectional view, in this case with two different embodiments of a movable gas discharge channel on both sides of an axis of symmetry a: Left-hand gas discharge channel 33c is composed in the flow direction of a horizontally rail-guided outlet opening 31c, a connecting flexible section 38c and a swivellable section 36c, which is fluidically connected at a hinge 37c to a fixed section 35.

[0072] Right-hand gas supply channel 33d comprises an outlet opening 31d comparable to outlet opening 31c, to which a flexible section 38d for example comprising a corrugated tube is connected, which is coupled mechanically and fluidically directly, i.e. in particular without the interposition of a hinge, to fixed section 35.

[0073] Swivellable section 36c and flexible section 38d can be swivelled in an essentially V-shaped niche 43, which adjoins opening 41 on its side facing away from building field 8. Outlet openings 31c, 31d run on a rail 50, which runs transversely through entire opening 41 in chamber wall 4 and parallel to building field edge 81. Outlet openings 31c, 31d can thus be displaced horizontally along the entire length extent of building field edge 81, without thereby passing over it and thus passing into or over building field 8. Since they run rail-guided in the plane of chamber wall 4, they at no time impair the action of the coater (not represented). Together with outlet openings 31c, 31d, a partition wall, a linked curtain or a blind 55 can be moved on raid 50, which covers or closes opening 41 beside outlet openings 31c, 31d in alignment with chamber wall 4. It can keep a movement space of swivellable section 36c or of flexible section 38d inside V-shaped niche 43 free from impurities.

[0074] FIG. 6 shows a further diagrammatic cross-sectional view with a rail-guided movable outlet opening 31d and a flexible section 38d in V-shaped niche 43 according to FIG. 5. Diverging therefrom, however, rail 50 lies close to building field edge 81, in order to cooperate with a gas inlet 30 on a shorter path. An arrangement of outlet opening 31d close to the building field does not exclude the arrangement of a partition wall (not represented) for protecting opening 41 in chamber wall 4.

[0075] Outlet opening 31d acts on building field 8 in a main direction of action corresponding to axis b. A gas inlet 30 movable over building field 8 forms a flow cone 12 of the inflowing process gas and, for process-related reasons, is directed with its main direction of action corresponding to axis c at an angle to chamber wall 4. The two axes b, c thus enclose an angle α. Gas inlet 30 and gas outlet 32 are consequently not aligned coaxial with one another. As regards the control, an angle threshold value for angle α is stored, which must not be exceeded. Otherwise, the risk could arise that outlet opening 31d no longer completely covers flow cone 12, so that parts of its gas volume are not discharged directly out of process chamber 3, but beforehand can lead for example to undesired turbulence. Flow cone 12 is, in the plan view show here, a partial portion of trapezoidal target flow supply zone 21, which extends from the inlet opening of gas inlet 30 in the direction of outlet opening 31d of gas outlet 32. Target flow supply zone 21 represents a defined minimum area of action of gas inlet 32, from which impurities of the atmosphere of process chamber 3 are effectively removed. A target ventilation zone 22 semicircular in plan view extends around outlet opening 31d of gas outlet 32 and forms a defined minimum area of action of gas outlet 32. Location and optionally orientation and extension of target flow supply zone 21 and of target ventilation zone 22 are coordinated in the control with the position of process point 9 on building field 8, in such a way that the most effective possible removal of impurities from an area of process chamber 3 close to the building field takes place above building field 8. A particularly favourable alignment of gas inlet 30 and gas outlet 32 with one another is shown in the present representation, in that flow cone 12 and therefore a significant proportion of the impurity which has penetrated through inflowing gas from process point 9 is targeted essentially directly into the outlet opening of gas outlet 32. This reduces the probability of an undesired dwell of the impurity longer than necessary in process chamber 3, e.g. in the form of a vertical vortex or a roller.

[0076] FIG. 7 shows a further diagrammatic cross-sectional view of a gas outlet 32 with an alternative movable or displaceable outlet opening 31e. V-shaped niche 43, which tapers from opening 41 in chamber wall 4, emerges on its side facing away from the building field into a fixed section 35e of a gas discharge channel 33e. A plurality of also fixed vertical wall sections 39e arranged in a fan-shaped manner lie in front in the flow direction. They give niche 43 the shape of an outlet funnel segmented in the horizontal direction. Each section 39e emerges on the building field side with an outlet opening 31e in the extension plane of chamber wall 4. Each outlet opening 31e can be closed preferably fluid-tight with a slat 54 displaceable in the plane of chamber wall 4 independently of an adjacent or another outlet opening 31e.

[0077] FIG. 8 shows a view of chamber wall 4 according to intersecting line VIII-VIII in FIG. 7. The essentially horizontally extending rectangular opening 41, which extends transversely and over the length of building field edge 81, is divided geometrically viewed into six square areas 56. Two of the latter represent outlet openings 31e, the remaining ones are closed by slats 54. By actuating slats 54, square areas 56 can be switched in each case independently of one another from a closed position into outlet openings 31e. Outlet openings 31e at building field edge 81 can thus be changed very flexibly and quickly in their position. A positional change of outlet openings 31e lasts only as long as square area 56 is opened or closed. Opening 41 can also be controlled in patterns other than the manner represented in FIG. 8, for example with only one outlet opening 31e corresponding to a square area 56, with two or more areas 56 lying beside one another as outlet opening 31e up to all opened areas 56 as a single outlet opening 31e. Outlet opening(s) 31e can thus be varied not only with regard to their position, but also with regard to their size.

[0078] In a simpler embodiment, opening 41 can comprise precisely four horizontally displaceable slats 54, so that two square areas 56 remain unclosed as outlet openings 31e. Unclosed areas 56 or outlet openings 31e can be arranged at each of the six positions inside opening 41 and also beside one another.

[0079] FIG. 9 shows a view of chamber wall 4 with an opening 41. It is composed of two rows 57 lying vertically above one another in chamber wall 4 comprising in each case six square areas 56. Each row 57 is constituted and controlled in principle like opening 41 according to FIG. 8. Displaceable slats 54 form as it were a linked curtain, which has a high temperature resistance on account of the temperatures prevailing in process chamber 3.

[0080] In the represented pattern, i.e. with an identical control of upper and lower row 57, the suction intensity at building field edge 81 can be locally intensified. With a respectively individual control of upper and lower row 57, on the other hand, one or more outlet openings 31e can be moved above one another and independently of one another and their position can be adapted to the present requirements for example of the position of a plurality of movable gas inlets or a current concentration or quantity of impurities of the gas atmosphere over the building field 8.

[0081] FIG. 10 shows a view of chamber wall 4 according to intersecting line X-X in FIG. 5. In rectangular opening 41, which extends transversely and over the length of building field edge 81, two outlet openings 31c and 31d can be displaced horizontally. They thus cover entire building field edge 81 in terms of flow.

[0082] FIG. 11 shows a comparable view to FIG. 10, but with two openings 41 lying vertically one above the other. Outlet openings 31c or 31d can be moved horizontally in each of openings 41. The latter can thus be moved completely independently of one another and achieve a high concentration of their effectiveness in particular in a vertical direction.

[0083] Since the preceding manufacturing devices described in detail are examples of embodiment, they can be modified in the usual manner by the person skilled in the art over a wide range, without departing from the scope of the invention. In particular, the specific embodiments of the outlet openings can follow in a shape other than in the one described here. The process chamber and the building field can also be constituted in a different form, if this is necessary for space reasons or on design grounds. Furthermore, the use of the indefinite article “a” does not exclude the fact that the features concerned may also be present several times or repeatedly.

LIST OF REFERENCE NUMBERS

[0084] a1 laser sintering or laser fusion device

[0085] a2 object

[0086] a3 process chamber

[0087] a4 chamber wall

[0088] a5 building container

[0089] a6 wall

[0090] a7 working plane

[0091] a8 building field

[0092] a10 movable carrier

[0093] a11 base plate

[0094] a12 building platform

[0095] a13 unsolidified building material

[0096] a14 storage container

[0097] a15 powder-like building material

[0098] a16 coater

[0099] a18 overflow container

[0100] a20 illumination device

[0101] a21 laser

[0102] a22 laser beam

[0103] a23 deflection device

[0104] a24 focusing device

[0105] a25 coupling window

[0106] a29 control unit

[0107] a30 gas inlet nozzle

[0108] a31 gas outlet nozzle

[0109] a32 gas supply channel

[0110] a33 gas discharge channel

[0111] a34 gas flow

[0112] 3 process chamber

[0113] 4 chamber wall

[0114] 8 building field

[0115] 9 process point

[0116] 12 flow cone

[0117] 21 target flow supply zone

[0118] 22 target ventilation zone

[0119] 30 gas inlet

[0120] 31, 31a . . . 31e outlet opening

[0121] 32 gas outlet

[0122] 33, 33a . . . 33e gas discharge channel

[0123] 35, 35a . . . 35e fixed section

[0124] 36, 36a . . . 36c swivellable section

[0125] 37, 37a . . . 37c hinge

[0126] 38c . . . 38d flexible section

[0127] 39e fixed section

[0128] 41 opening

[0129] 42, 43 niche

[0130] 50 rail

[0131] 54 slat

[0132] 55 blind

[0133] 56 square area

[0134] 57 row

[0135] 81 building field edge

[0136] a axis of symmetry

[0137] b effective axis of gas outlet 32

[0138] c effective axis of gas inlet 30

[0139] v quarter-circle arc αangle between axes b, c