MANUFACTURING DEVICE AND METHOD FOR ADDITIVE MANUFACTURING WITH MOVABLE GAS FLOW SUPPLY

Abstract

The invention relates to a manufacturing device for the additive manufacturing of a three-dimensional object and a corresponding method. The object is manufactured by applying a building material in layer-wise form and selectively solidifying the building material at points corresponding to the cross-section of the object. The points are scanned with at least one exposure area, and, during operation, a movable gas inlet approaches a reference process point and/or a target flow supply zone assigned to the reference process point for the flow supply with the process gas, and the process gas is discharged via a stationary 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 movable inside the process chamber for introducing process gas into the process chamber and with at least one stationary gas outlet for discharging the process gas from the process chamber.

2. The manufacturing device according to claim 1, wherein the gas inlet is movable in a lower half relative to a clear height of the process chamber.

3. The manufacturing device according to claim 1, wherein the gas inlet is movable in more than one degree of freedom in translation and/or one degree of freedom in rotation.

4. The manufacturing device according to claim 1, wherein the gas inlet is movable above the building field.

5. The manufacturing device according to claim 1, wherein the number of the gas inlets diverges from the number of the activatable energy beam bundles.

6. The manufacturing device according to claim 1, wherein more than two gas inlets are able to be moved independently of one another.

7. The manufacturing device according to claim 1, further comprising an additional stationary gas inlet.

8. A method for producing a three-dimensional object by means of an additive manufacturing device with at least one movable gas inlet for introducing process gas into a process chamber and at least one stationary gas outlet for discharging the process gas from the process chamber, according to 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 a movable gas inlet approaches during operation a reference process point and/or a target flow supply zone assigned to the reference process point for the flow supply with process gas, and the process gas is discharged via a stationary gas outlet.

9. The process according to claim 8, wherein during operation more than one gas inlet is assigned to a reference process point and/or a target flow supply zone.

10. The method according to claim 8 with a coordination of a gas inlet supplying a flow to a reference process point and/or a target flow supply zone depending on a current position and/or orientation of the reference process point and/or of the target flow supply zone, wherein the travel path of the gas inlet is dependent on the movement of the reference process point and/or of the target flow supply zone, wherein the control of the gas inlet in such a way that the reference process point and/or the target flow supply zone always lies, in a plan view onto the building field, in a predefined flow course zone between the opening of the gas inlet and the opening of the gas outlet.

11. The method according to claim 8, wherein an angle, which the opening planes of the gas inlet and gas outlet and/or which a mean flow direction when the process gas exits from the gas inlet and a normal erected on an opening plane of the gas outlet enclose with one another in plan view, does not exceed a predefined angle threshold value with one another.

12. The method according to claim 8 with a movable gas inlet, which is assigned to a reference process point and/or a target flow supply zone, wherein a maximum distance and/or a minimum distance and/or target flow supply zone is/are defined.

13. The method according to claim 8 with a segmentation of the building field into a plurality of building field segments, wherein at least one movable gas inlet is assigned at least temporarily to a predefined building field segment, in which a current reference process point and/or, above the latter, a current target flow supply zone lies.

14. The method according to claim 8, further comprising an interconnection of at least two movable gas inlets.

15. The method according to claim 8, further comprising a coordination of a least two movable gas inlets in such a way that, viewed in a vertical plan view onto the building field, the gas inlets with an identical orientation and/or with an identical mean flow supply direction are not positioned behind one another in the same mean flow supply direction and/or the flow course zones assigned in each case to the gas inlets and/or the target flow supply zones remain free from overlapping relative to one another and/or the gas inlets are arranged rotated and/or displaced with respect to one another in such a way that their respective mean flow supply directions do not intersect one another.

Description

[0049] The principle of the invention is explained in greater detail below by way of example with the aid of a drawing. In the figures:

[0050] 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,

[0051] FIG. 2: shows a diagrammatic partial cross-sectional view of a device according to an embodiment of the invention with a gas inlet in a plane corresponding to intersecting line D-D according to FIG. 1,

[0052] FIG. 3: shows a diagrammatic cross-sectional view of the device according to an alternative embodiment of the invention with a rotating gas inlet,

[0053] FIG. 4: shows a diagrammatic cross-sectional view of the device according to a further embodiment of the invention with three gas inlets,

[0054] FIG. 5: shows a diagrammatic cross-sectional view of the device according to a further embodiment of the invention with two gas inlets,

[0055] FIG. 6: shows a perspective view of a gas inlet moved by means of a robot arm, and

[0056] FIG. 7: shows a plan view of an alternative robot arm.

[0057] The device represented diagrammatically in FIG. 1 is a laser sintering or laser fusion device a1 known per se. For the building of an object a2, it contains a process chamber a3 with a 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.

[0058] Arranged in container a5 is a carrier a10 movable in a vertical direction V, to which a base plate a11 is fitted, which terminates building container a5 downwards and thus forms the bottom thereof. Base plate a11 can be a plate formed separately 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 a11, on which platform object a2 is built up. Object a2 can however also be built up on base plate a11 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.

[0059] 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.

[0060] Laser sintering device a1 also contains an illumination device a20 with a laser a21, which generates a laser beam a22 as an energy beam bundle, which is deflected by a 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 onto which working plane a7 is focused.

[0061] 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 a 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 the control unit.

[0062] 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. To be on the safe side, coater a16 pushes a somewhat larger quantity of building material a15 in front of it than is required for the building 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.

[0063] The cross-section of object a2 to be manufactured is then scanned by laser beam a22 with a radiation exposure area (not shown), which represents diagrammatically an overlap of the energy beam bundle with working plane a7. Powder-like building material a15 is thus solidified at 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.

[0064] To generate a preferably laminar process 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 outlet opening a31 and a gas discharge channel a33. Process gas flow a34 moves away over building field a8. The gas supply and discharge can also be controlled by control unit a29 (not represented). The gas extracted from process chamber a3 can be fed 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 result of which an air circulation system with a closed gas circuit is formed. Instead of just one gas inlet nozzle a30 and one gas outlet opening a31, a plurality of nozzles or openings can also be provided in each case.

[0065] FIG. 2 shows a cross-sectional view onto a building field 8 according to intersecting line D-D in FIG. 1. Powder-like building material, in this case metallic or metal-containing powder, completely covers the area of square building field 8, which an ascending chamber wall 4 of a cuboid process chamber 3 surrounds. In the viewing direction of FIG. 2, a laser beam a22 as an energy beam bundle with a radiation exposure area strikes a point-like process point 9 as a reference process point on building field 8. There, it melts the building material, as a result of which impurities of the process atmosphere such as for example splashes, smoke or condensate can arise.

[0066] A movable gas inlet 30 is positioned on the right-hand side beside process point 9. Gas inlet 30 can be displaced in both spatial directions parallel to building field 8 and in addition can be rotated in its displacement plane about a rotary axis running perpendicular thereto. It supplies a flow to process point 9 and/or the area of the process chamber lying above the latter with a process gas in order to remove impurities from the area and optionally to largely prevent oxidation of building material at process point 9. The process gas and any smoke gas and/or condensate and/or further particles pass in a flow cone 12 proceeding from gas inlet 30 into a stationary gas outlet 31. Gas outlet 31 is housed in chamber wall 4 and extends there parallel to building field 8. Its length L in or parallel to the extension plane of building field 8 exceeds the side length l of a side of building field 8.

[0067] A control unit (not represented) provides for the control of the movements of gas inlet 30. It takes account of a maximum distance d, which gas inlet 30 can at maximum occupy with respect to process point 9. It thus provides for an adequate proximity of gas inlet 30 with respect to process point 9 and ensures its reliable flow supply with process gas.

[0068] Flow cone 12 arises from jet widening of the process gas flowing out jet-like from gas inlet 30. The outflowing process gas and the process gas for the most part at rest in process chamber 3 have different speeds. Between them, a shearing layer arises, from which a widening free jet develops, in that the process gas surrounding it is sucked in and drawn along with it. Flow cone 12 can be described in plan view approximately as an equilateral trapezium 13, the longer base side or base 14 whereof runs parallel to an outlet opening of gas outlet 31 and shorter base side 15 whereof runs parallel to an inlet opening of gas inlet 30. The control unit (not represented) controls movable gas inlet 30 in such a way that process point 9 always lies inside trapezium 13.

[0069] The control unit can thus assign an area inside building field 8 to gas inlet 30 with trapezium 13, in which process point 9 can lie. As long as process point 9 moves inside trapezium 13, gas inlet 30 does not need to change in its position. Consequently, movements of gas inlet 30 and the control required for this can be reduced, if the control unit for gas inlet 30 and optionally for each further gas inlet 30 can assume a trapezium area 13 as a working area on or above building field 8. In addition, it can take account of the fact that trapezium area 13 increases with increasing distance of gas inlet 30 from gas outlet 31, wherein in contrast the speed and effectiveness of the flow supply diminishes with increasing distance of the free jet.

[0070] For gas inlet 30 directed frontally onto gas outlet 31, trapezium 13 described above can at all events be assumed as flow cone 12. As soon as gas inlet 30 is set at an angle α with respect to gas outlet 31 as in FIG. 3, a trapezium 13 results, base 14 of which is inclined at the same angle α with respect to the outlet opening of gas outlet 31. However, because base 14 in any case usually lies outside building field 8, there is no relevant difference for the consideration of an area which can be supplied with a flow above building field 8 even with the set gas outlet 30.

[0071] FIG. 3 illustrates moreover that an area above building field 8 can be subjected to a flow much more quickly by a rotation of gas inlet 30 than by its displacement. Displaceable and also rotatable gas inlet 30 thus enables a rapid and targeted flow supply to process point 9.1, which moves following the curved course of arrow P to the location of process point 9.2. With the combination of a displaceability of gas inlet 30 with its rotatability, slower travel movements of gas inlet 30 can be reduced in favour of its more rapid rotation movements. Gas inlet 30 is thus able to track a change in location of process points 9.1, 9.2 more quickly.

[0072] In combination with a movable gas outlet, a rotation of gas inlet 30 would require a large and relatively time-consuming displacement movement of the gas outlet. According to the invention, movable gas inlet 30 is combined with a stationary gas outlet 31. Its large length extension L along or parallel to a side of building field 8 promotes a targeted removal of gas from process chamber 3. The considerable control requirement for a movable gas outlet and a considerable time consumption for its travel movements are thus dispensed with. The control advantages of movable gas inlet 30 can be fully utilised together with stationary gas outlet 31.

[0073] FIG. 4 shows three gas inlets 30a, 30b, 30c, which are assigned to two process points 9.1, 9.2. Gas inlets 30a, 30b, 30c in the represented process situation are arranged in parallel beside one another and directed frontally onto gas outlet 31. Building field 8, above which they are located, is formally divided in terms of process into four square segments I, II, III, IV. The segmentation of building field 8 should be considered as having taken place based on need, inasmuch as it is guided by probabilities of the presence of process points 9.1, 9.2 in segments I, II, III, IV. For this purpose, it is assumed here that process points 9.1, 9.2 are often located simultaneously in segments I and III.

[0074] The position of the three gas inlets 30a, 30b, 30c is assigned in FIG. 4 to segment II, from which they supply a flow in common to complete segment I, in which the two process points 9.1, 9.2 are located. As long as they move solely in segment I, a control of gas inlets 30a, 30b, 30c is not required. The segmentation of building field 8 on the one hand optionally together with a control-based coupling of gas inlets 30a, 30b, 30c on the other hand reduces their control outlay and their travel paths.

[0075] If process points 9.1, 9.2 are displaced into segment III, gas inlets 30a, 30b, 30c are jointly guided over segment IV. Instead of three individual control procedures, only a single control procedure of gas inlets 30a, 30b, 30c coupled by control technology is required. If need be, the control-based coupling of gas inlets 30a, 30b, 30c can be suspended completely or partially or temporarily or permanently if a process step requires this. Thus, for example, gas inlets 30a, 30b can be jointly assigned to process point 9.1, which is displaced into segment II, while gas inlet 30c supplies a flow to process point 9.1 in segment IV (not shown).

[0076] FIG. 5 shows two gas inlets 30a, 30b, which are assigned to a single process point 9 and they supply a flow in common. Gas inlets 30a, 30b are not directed frontally onto gas outlet 31, but rather set at an angle β or γ to the latter. They each describe a trapezium 13, which mutually overlap in sections. Due to flow cones 112 directed at an angle to one another, it is to be assumed that their flows are mutually influenced. Due to the flow jet deflection, it can thus be assumed from this that an area 20 facing away from gas inlets 30a, 30b and facing towards gas outlet 31 and computationally not covered by trapezium 13 is nonetheless reliably subjected to a flow.

[0077] Apart from maximum distance d according to FIG. 2, the control unit also takes account of a maximum value for angle β or γ according to FIG. 5, by which gas inlets 30a, 30b may be rotated with respect to gas outlet 31. If the effective directions of gas inlets 30a, 30b and of gas outlet 31 are at an unfavourable, i.e. not sufficiently obtuse, angle to one another, it can lead to undesired turbulence and to an insufficient removal especially of smoke-laden gas. A maximum value for angle β, γ thus ensures a reliable purging of the surroundings of process points 9.1, 9.2.

[0078] FIG. 6 shows, in the partial cross-sectional perspective view of process chamber 3, a robot arm 22, which comprises two articulated joints 24 and can be rotated about a rotary axis D. At its free end, it carries a rotatable wide gas inlet 30d, which is supplied via a flexible gas supply channel 32. Robot arm 22 lies in process chamber 3 inside wall 4 and outside building field 8, so that gas inlet 30d can pass completely over building field 8 with a variable horizontal position and preferably in addition with a variable vertical distance therefrom, in order to approach a target flow supply zone 21 and supply a flow to it in a controlled manner. Gas inlet 30d comprises four nozzle-shaped inlet openings 33, from which a horizontally and vertically widening flow cone 12 emerges in common. Flow cone 12 lies in the area of gas inlet 30d at a height h just above target flow supply zone 21 of building field 8. Height h diminishes with the distance from gas inlet 30d and becomes h=0 when flow cone 12 contacts building field 8.

[0079] FIG. 7 offers a plan view onto a process chamber 3 with a robot arm 23, which is also arranged between wall 4 and building field 8. At its free end, it carries a narrow gas inlet 30e, which can travel horizontally or vertically above building field 8, in order to bring about a flow supply with a narrow flow cone 12. It comprises an articulated joint 24 and it or gas inlet 30e can be swivelled about vertical rotary axes D. For a flow supply to entire building field 8, a plurality of such robot arms 23 can be arranged in process chamber 3 and controlled separately or in common in the manner described above.

[0080] Since the preceding 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 gas inlets in a form other than in the one described here can take place. The gas outlet or also the process chamber can also be constituted in another 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

[0081] a1 laser sintering or laser fusion device [0082] a2 object [0083] a3 process chamber [0084] a4 chamber wall [0085] a5 building container [0086] a6 wall [0087] a7 working plane [0088] a8 building field [0089] a10 movable carrier [0090] a11 base plate [0091] a12 building platform [0092] a13 unsolidified building material [0093] a14 storage container [0094] a15 powder-like building material [0095] a16 coater [0096] a18 overflow container [0097] a20 illumination device [0098] a21 laser [0099] a22 laser beam [0100] a23 deflection device [0101] a24 focusing device [0102] a25 coupling window [0103] a29 control unit [0104] a30 gas inlet nozzle [0105] a31 gas outlet opening [0106] a32 gas supply channel [0107] a33 gas discharge channel [0108] a34 gas flow [0109] 3 process chamber [0110] 4 chamber wall [0111] 8 building field [0112] 9, 9.1, 9.2 process point [0113] 12 flow cone [0114] 13 trapezium (area) [0115] 14 longer base line, base [0116] 15 shorter base line [0117] 20 area [0118] 21 target flow supply zone [0119] 22, 23 robot arm [0120] 24 articulated joint [0121] 30, 30a . . . 30e gas inlet [0122] 31 gas outlet [0123] 32 gas supply channel [0124] 33 inlet openings [0125] α, β, γ setting angle [0126] d distance [0127] h height above building field 8 [0128] D rotary axis [0129] I side length of building field 8 [0130] L extension length of gas outlet 31 [0131] P arrow [0132] I . . . IV segments of building field 8