DE202009016400U1 - Device for the production of moldings by layering of material powder - Google Patents

Abstract

Apparatus for the production of moldings by layer-wise building up from material powder by locally selective solidification of the powder to coherent areas in accordance with Geometriebeschreibungsdaten of the molding, comprising
A process space (9) having a process space bottom (11) which has a base plane (51) and a height-adjustable construction platform (13) for the molded body which is controlled relative thereto by means of a controllable drive unit along a vertical construction platform axis,
A powder layer preparation device for preparing a respective subsequently selectively selectively solidified powder layer (21) on the construction platform (13) and
A powder hardening device which can be activated for the purpose of selectively solidifying powder of the last powder layer (21) prepared on the construction platform (13),
wherein the powder layer preparation device (41) comprises a powder supply device for providing powder in the process space (9) and a smoothing slide (43) with a powder smoothing strip (47) for distributing and smoothing the powder provided on the construction platform (9) by the powder supply device in the process space (13) ), wherein the smoothing slide (43) with its powder smoothing strip (47) between two ...

Description

• – einen Prozessraum mit einem Prozessraumboden, der eine Basisebene und eine relativ dazu mittels einer steuerbaren Antriebseinheit längs einer vertikalen Bauplattformachse gesteuert höhenverstellbare Bauplattform für den Formkörper aufweist,
• – eine Pulverschichtenpräparierungseinrichtung zur Präparierung einer jeweiligen nachfolgend ortsselektiv zu verfestigenden Pulverschicht auf der Bauplattform und
• – eine Pulververfestigungseinrichtung die zum ortsselektiven Verfestigen von Pulver der jeweils zuletzt auf der Bauplattform präparierten Pulverschicht aktivierbar ist,

wobei die Pulverschichtenpräparierungseinrichtung eine Pulverversorgungseinrichtung zur Bereitstellung von Pulver in dem Prozessraum und einen Glättungsschieber mit einer Pulverglättungsleiste zur Verteilung und Glättung des von der Pulverversorgungseinrichtung im Prozessraum bereitgestellten Pulvers auf der Bauplattform aufweist, wobei der Glättungsschieber mit seiner Pulverglättungsleiste zwischen zwei Umkehrstellen mit in Draufsicht dazwischenliegender Bauplattform im Prozessraum hin- und herbewegbar ist, um die Pulverglättungsleiste in einem der gewünschten Pulverschichtdicke entsprechenden Abstand zu der im jeweils vorausgegangenen Schritt auf der Bauplattform ortsselektiv verfestigten Pulverschicht über die Bauplattform hinwegzubewegen.The invention relates to a device for the production of moldings by layer-wise building up of material powder by locally selective solidification of the powder to coherent areas in accordance with Geometriebeschreibungsdaten of the molding comprising

• A process space having a process space bottom, which has a base plane and a height-adjustable construction platform for the shaped body controlled in a controlled manner by means of a controllable drive unit along a vertical construction platform axis,
• A powder layer preparation device for preparing a respective subsequently location-selectively solidified powder layer on the building platform and
• A powder hardening device which can be activated for site-selective solidification of powder of the powder layer last prepared on the building platform,

wherein the powder layer preparation device has a powder supply device for providing powder in the process space and a smoothing slide with a powder smoothing strip for distributing and smoothing the powder provided on the construction platform by the powder supply device in the process space, the smoothing slide with its powder smoothing strip being located between two reversal points with a construction platform in between Process chamber is moved back and forth to the powder smoothing bar in a desired powder layer thickness corresponding distance to the spatially in the respective previous step on the build platform solidified powder layer over the build platform move away.

Such devices for the production of moldings are known in various embodiments. Fundamental differences between known devices of this type result from the mode of action of the powder hardening device. Thus, there are devices in which the powder consolidation by locally selective application of a binder or chemical reactants on the last prepared on the build platform powder layer in order to solidify them at the relevant sites to contiguous areas, with correspondingly solidified areas at the respectively below connect the lying layer.

However, in recent years, another working principle has been found to be of particular interest in the site-selective solidification of powder, namely solidification by remelting or, if appropriate, sintering of the powder by energy input by radiation, in particular laser radiation. The mode of remelting the powder is referred to herein as Selective Laser Melting (SLM). Selective laser melting is used to produce shaped bodies of metallic powders and / or ceramic powders. The devices used for this purpose are also referred to as SLM devices and are known in various variants, such. B. from the DE 10 2004 041 633 A1 , of the DE 102 36 907 A1 , of the DE 199 05 067 A1 , of the DE 10 112 591 A1 or the WO98 / 24574 A1 , These SLM devices are used to produce a shaped body according to geometric data, in particular CAD data, the shaped body by layering of powdered, metallic or ceramic material, wherein successively more powder layers are applied one above the other and each powder layer before applying the next powder layer with a focused laser beam in a predetermined area corresponding to a selected cross-sectional area of the molding is heated. The laser beam is guided in each case in accordance with the CAD cross-sectional data of the selected cross-sectional area of the molded body or data derived therefrom via the respective powder layer. As a result of the energy input of the laser radiation, the material powder is locally remelted in the region of the point of impact of the laser beam so that contiguous regions arise as homogeneously as possible of remelted material in the respective layer. Superimposed remelted areas of two successive layers combine, so that the shaped body arises coherently layer by layer.

The quality of the preparation of the successive powder layers on the construction platform in terms of maintaining a respective predetermined layer thickness and the creation of a respective planar powder layer surface plays an essential role in selective laser melting, since it determines the homogeneity of the melted and re-solidified material of the molded article. This applies both to the production of a shaped body according to the principle of selective laser melting and in the production of a shaped body according to the principle of selective laser sintering, in which the powder material is not completely melted through, but is sintered at the irradiated points. Usually, multicomponent powder materials are used which have different melting points.

The preparation of a respective new powder layer on the construction platform should take as little time as possible, irrespective of the powder consolidation principle used, so that the construction process of the molding as a whole can take place as quickly as possible.

Furthermore, little excess powder should be produced during each building process. Within the process space, the powder should preferably remain concentrated on a relatively small area enclosing the build platform to avoid unnecessary contamination of the process space.

Object of the present invention is to provide a device of the type mentioned, which allows improved handling of the material powder in the process space during the construction process.

This object is achieved in that in a device of the type mentioned, the Pulverglättungsleiste is controlled in height adjustable in their movement between the reversal points relative to the process space floor.

Due to the possibility of raising and lowering the powder smoothing bar, the process space floor area on which powder is applied can be kept very small and well demarcated. Care must be taken to ensure that the powder smoothing strip is brought so close to the base plane of the processing chamber floor when the construction platform is swept over that the powder layer with the desired powder layer thickness is produced on the construction platform. In practice, the underside of the Pulverglättungsleiste will lie when sweeping the build platform in the base level of the process room floor, the construction platform is lowered accordingly. However, the Pulverglättungsleiste will push a respective remaining amount of powder before passing through the build platform. In order to avoid that this residual amount of powder is transported out of the vicinity of the construction platform, the Pulverglättungsleiste can now be raised relative to the base level of the process space floor and moved in the raised state further towards the next reversing point. In the process, the residual amount of powder initially displaced beyond the build platform is, as it were, skipped by the powder smoothing bar. Before the next return movement of the powder smoothing bar in the direction of the construction platform, the powder smoothing bar can be lowered in time so that it can take the said amount of residual powder back towards the construction platform.

In each case a new amount of powder for the layer preparation is always supplied by the powder supply device in an area of the process space floor between the two reversal points of the powder smoothing bar.

In this case, the respectively delivered quantity can be dimensioned for the preparation of a single powder layer or optionally also be metered for the preparation of several powder layers.

The respective subsequent delivery of powder in the process room can, for. B. during the phases in which the Pulververfestigungseinrichtung is activated for the site-selective solidification of powder of the last prepared on the building platform powder layer.

Such a procedure is preferably selected in an embodiment of the invention in which the powder supply device has a powder feed channel connected to a powder reservoir located outside the process space and a conveyor for conveying powder in the powder feed channel, the powder feed channel being connected to at least one between the powder feed channel Building platform and one of the reversal points of Pulverglättungsleiste lying powder inlet point opens into the process chamber to direct powder directly to the process room floor. In alternative variants of the invention, a supply of the material powder can be provided from above.

The powder smoothing bar is adjustable in height such that it is alternately lifted off the base plane of the process chamber floor during movement over the powder inlet point or close to the base plane of the process chamber floor. In practice, the powder smoothing bar in the close approximated state will contact the base plane of the process room floor. The powder smoothing bar should then be lowered if it is to take powder from the powder intake point when moving towards the build platform. During the return motion, the powder smoothing bar should then be raised when sweeping the powder intake point so that it can not move powder in the direction away from the build platform.

Preferably, the smoothing slider has a movably guided between the reversal points arm on which the powder smoothing bar is arranged vertically adjustable. The powder smoothing bar preferably comprises an elastically compliant powder wiping element of a rubbery or silicone-like material.

According to one embodiment of the invention, a pneumatic and / or electromagnetic and / or hydraulic actuator for the controlled height adjustment of the Pulverglättungsleiste is provided. In the case of a pneumatic actuator, this z. B. be operated with inert gas as working gas, which may be the protective gas to be used anyway for the production of a working atmosphere in the process space. The actuator should be controllable, although not necessarily a particularly sophisticated control provided must be because the smoothing slider with two discrete height settings, namely a lowered and a raised basically can get along.

In any case, the smoothing slider should be controllable by means of a control device such that the powder smoothing bar has a predetermined movement profile of the height adjustment movement during the movements between the reversal points. The height adjustment can be accompanied by the translational movement of the powder smoothing strip simultaneously. Alternatively, the translational movement may also be interrupted to raise or lower the powder smoothing bar.

According to one embodiment of the invention, a mechanical actuator is provided, which derives the height adjustment of the powder smoothing strip from the movement drive for the translational movement between the reversal points. Such a mechanical actuator may include cams.

According to a preferred development of the invention, the smoothing slide has a further powder smoothing bar, which delimits an open space to the process space bottom with the one powder smoothing bar, whereby the further powder smoothing bar can also be adjusted in height in its movement between the reversal points relative to the process space bottom.

The two Pulverglättungsleisten can be independently adjustable in height.

Preferably, the smoothing slider is controllable by means of a control device such that the Pulverglättungsleisten are alternately raised or lowered in the movements between the reversal points, the respective advancing in the direction of movement Pulverglättungsleiste is raised while the trailing Pulverglättungsleiste is lowered. The raising or lowering preferably takes place at the reversal points.

In a particularly preferred embodiment of the invention, the powder feed channel opens from below into the process chamber bottom at a powder inlet point located between the build platform and one of the reversal points of the powder smoothing strip. In this preferred case, the conveyor thus presses the respectively desired amount of powder from below into the process space. The smoothing slider, which is then set in motion, then takes the powder by means of the powder smoothing strip to the building platform in order to deposit it there in a uniform layer of the desired thickness.

For powder conveying in the powder guide channel in the direction of the process space, a screw conveyor has proven to be particularly suitable, which has a provided in the powder feed channel screw conveyor. The powder feed channel may, for. B. include a tube or possibly a powder feed hose made of flexible material.

The device according to the invention is preferably an SLM device, in which the powder compaction device has an irradiation device with a radiation source, in particular a laser radiation source whose radiation is to be directed to the construction platform in a location-selective manner, to powder of a powder layer which has been lastly prepared thereon Remelt areas. According to a further embodiment of the invention, the device is designed such that it can be used for carrying out the method of selective laser sintering.

The construction platform can preferably be lowered relative to the base plane of the process chamber floor by the amount of a desired powder layer thickness into a new lowered position in order to receive a respective new powder layer. The construction platform can still be moved vertically controlled after a respective preparation of a powder layer in order to adjust the size of the beam impact point in the case of irradiation with a focused laser beam on the powder layer and / or possibly even to vary during the irradiation process.

An alternative embodiment of the smoothing pusher has a further powder flattening bar extending horizontally from the first powder flattening bar so that the powder flattening bars define a space open to the process room floor, the smoothing pusher with its powder flattening bars being positionable next to the building platform in a powder replenishing wait position such that the Powder inlet point opens into the intermediate space. In this case as well, a preferred embodiment of the invention has a powder inlet point which is provided in the process space bottom in order to introduce the powder from below into the process space and in particular into the space between the powder smoothing strips. During the reciprocating movement of the smoothing slide, excess powder not deposited on the building platform remains, at least for the most part, in the space between the powder smoothing strips and is thus prevented from contaminating the process space in an uncontrolled manner.

The powder inlet can be a z. B. round mouth hole of the powder supply channel with a relatively small diameter. In particular, in this case, it is suggested that the Powder smoothing bars in plan view have the shape of sheets that are convex in the powder replenishment waiting position of the smoothing slider toward the building platform axis. Such a particularly preferred solution has the advantage that during the movement of the smoothing slide out of the powder replenishment waiting position towards the building platform, the subsequently supplied powder quantity initially concentrated essentially in the area of the relatively small powder inlet point is rapidly distributed over a wider area of the trailing smoothing bar, so that the smoothing bar can spread powder material over the build platform at a sufficient width.

During the return movement of the smoothing slide, due to the curved shape of the smoothing slide bars, excess powder tends to collect again on a narrower peak area of the then trailing smoothing slide. Again, this is a measure to avoid uncontrolled contamination of the process space by excess powder.

The abovementioned advantages can also be used in the context of the invention in an embodiment with only one powder smoothing bar which, with its convex side, can distribute powder over a wider area and, with its concave side in front, can have a powder collecting effect on a narrower area. As mentioned above, the powder feed is preferably performed when the smoothing slide is in its powder replenishing waiting position, in a respective phase of powder compaction by means of the powder compacting means; in the case of selective laser melting during the irradiation phases of the powder layer.

With regard to the problem of as clean as possible a powder handling in the process space, it is also proposed that a powder extraction device be provided for the extraction of excess powder from the process space after completion of a relevant molding. This can be done, if necessary, in a protective gas atmosphere.

Embodiments of the device according to the invention will be explained in more detail below with reference to the figures.

1 shows in a perspective view of an SLM device according to the invention in an external view.

2a and 2 B show in a crude schematic way a snapshot during the process of irradiation of the last prepared powder layer on the build platform.

3 shows in a perspective view of the process space compartment of the device 1 in a largely disassembled state to reveal the view of a sheeting device.

4 shows in schematic representations a) -h) a sequence of snapshots in the layer preparation.

5 shows in a perspective view accordingly 3 a layer preparation device and the process space of a further SLM device according to the invention.

6 shows in a rough schematic way three snapshots of the operation of another embodiment of the invention.

1 shows as an example of a SLM device a SLM table device, which z. B. for the production of dental prostheses, jewelry, small machine parts, etc. may be used and in particular for the field of research on processes in selective laser melting (SLM) or possibly in selective laser sintering (SLS) is suitable.

The SLM device 1 has a housing 3 with a process room compartment 5 and a supply compartment 7 on. In the process room compartment 5 is the process room 9 with his process room floor 11 and the built-in platform 13 like this through the viewing window 15 in the front housing wall of the process room compartment 5 can be seen. A stereo microscope 17 can be used to observe the SLM building process and / or setting certain parameters, such as B. to check the focal adjustment of the laser beam used. In the opposite side walls of the process room compartment 5 are passage openings 19 provided, which are sealed by a designated Durchgriffs glove (not visible) to the outside. The process room compartment 5 is thus designed as a glove box and allows manual access to components in the process room 9 from the outside. During the building process of a molded article prevails in the process room 9 preferably inert gas atmosphere.

In the supply compartment 7 Among other things, components for the protective gas supply, components of the electronic control of the device and electrical components are provided.

In 2a is in a crude schematic way, a snapshot during the irradiation of a last on the build platform 13 prepared powder layer 21 shown. Starting from a first powder layer resting on a substrate plate 25 has been prepared, has the building process of the molding 23 started and then layer by layer up to the in 2a indicated snapshot has been continued. The powder used is z. As metal powder or possibly ceramic powder. After the preparation of a respective powder layer on the build platform 13 this is done by means of a laser beam 27 Site-selective irradiated at the points where the powder is to be remelted to contiguous solidified areas. The laser beam 27 scans the current layer to be irradiated 21 in a controlled manner from, for this purpose z. B. an XY Galvanoscanner 29 is used. Furthermore, the control device controls the switch-on / switch-off phases of the laser beam 27 ,

According to 2a is the laser beam 27 so focused that its focal point 31 at the surface of the powder layer 21 lies. The beam impact point 37 is thus extremely small at this point and the energy density of the laser beam in Strahlauftreffpunkt is very high.

The size of the beam impact point 37 and thus its energy density can be varied in the example shown by the fact that in a cylinder guide 33 along the vertical axis 35 controlled movable construction platform 13 is varied in their height adjustment. 2 B shows the example case that the build platform 13 after preparation of the current layer to be irradiated 21 by a Absenkmaß Y from the focal point 31 of the laser beam 27 has been lowered so that the laser beam 27 at the beam impact point 37 on top of the powder layer to be irradiated 21 again something is widened compared to the situation according to 2a , The beam impact point 37 on the powder layer to be irradiated 21 in 2 B has thus become larger and has per unit area a lower energy than the focal point corresponding Strahlauftreffpunkt 37 in 2a , By appropriate height adjustment of the construction platform 13 Thus, the size of the Strahlauftreffpunktes on the powder layer to be irradiated 21 be varied during the irradiation process, if desired. On the other hand, it is also possible that in each case at the beginning of a layer irradiation process, this focal adjustment or defocus by appropriate height adjustment of the construction platform 13 he follows.

In the 3 is the process space area of the 1 recognizable SLM device shown, wherein the housing 3 is shown in the largely disassembled state to the view of the Pulverschichtpräparierungseinrichtung 41 release. This includes a smoothing slider 43 , which is formed as a pivot arm, which is about a vertical pivot axis 45 between the in 3 shown first reversing position at a first reversal point and a second reversing position, not shown, at a respective second reversal point back and forth. In such a pivoting movement of the smoothing slider passes 43 the build platform 13 in the process room floor 11 to get a smooth layer of powder on the build platform 13 to create. The smoothing slider 43 has a powder smoothing bar for this purpose 47 made of silicone or the like., The underside of the building platform 13 at the base level 51 of the process room floor 11 lies. The powder is introduced into the process space by means of a powder supply device 9 promoted. The supplied powder is passed through a powder inlet or powder inlet 55 in the process room floor 11 from below into the process room 9 brought in. The powder inlet opening 55 is located at a location between the build platform 13 and the in 3 reversal point of the smoothing bar 47 Also includes a powder replenishment waiting position of the smoothing slider 43 is.

After feeding a dosed amount of powder into the process room 9 through the powder inlet opening 55 The control of the SLM device causes the smoothing slide 43 to, from the in 3 pivot position shown in the second reversing position to pivot, so that the case of the Pulverglättungsleiste 47 advanced powder to the build platform 13 arrives. The building platform 13 is previously the measure of the desired powder layer thickness in its cylinder guide 33 been lowered. Because the smoothing bar 47 when painting over the construction platform 13 with its underside at the base level 51 of the process room floor 11 Thus, a smoothed powder layer of the desired thickness is produced and then the irradiation process for the site-selective solidification of the previously prepared powder layer can begin.

The movement of the powder smoothing bar 47 at the float between the reversal points 58 . 60 is in schematic snapshots in 4a -H illustrated. The arrows in the 4a -H should indicate the direction of movement of the powder smoothing bar. 4a shows the powder smoothing bar 47 at the first reversal point 58 , in the lowered state with at the base level of the process space floor 11 lying bottom. The powder supply device has at the powder inlet point 55 conveyed a certain amount of powder into the process space, this amount of powder according to 4a first in an area between the first reversal point 58 and the build platform 13 is present. The powder smoothing bar 47 is then based on the situation according to 4a horizontally towards the second reversal point 60 moves, taking the build platform 13 passes over, as in 4b can be seen. The construction platform 13 has previously been lowered by the degree of the desired powder layer thickness, so that during the movement of the Pulverglättungsleiste 47 according to 4b Powder on the building platform 13 applied and to a homogeneous powder layer 21 is leveled.

4c shows the situation in which the powder smoothing bar 47 the build platform 13 completely overpainted and a residual amount 62 pushed on powder in front of him. Based on the situation according to 4c becomes the powder smoothing bar 47 from the process room floor 11 lifted off, allowing them on their further movement towards the second reversal point 60 over the mentioned powder residue 62 is guided away, as in 4d is indicated.

Upon reaching the second reversal point 60 becomes the powder smoothing bar 47 back to the process room floor 11 lowered (cf. 4e and f), finally towards the first reversal point 58 to be moved back. The powder smoothing bar passes over it 47 again the build platform 13 , wherein they are the powder residue in question 62 in the area of the powder mixing point 55 shifts (cf. 4g ). Before reaching the first reversal point 58 becomes the powder smoothing bar 47 but again from the process room floor 11 lifted off, leaving them over the powder intake point 55 and the powder lying on it can be led away (cf. 4g and h). Upon reaching the first reversal point 58 becomes the powder smoothing bar 47 then finally back to the process room floor 11 lowered, like this in 4h is indicated.

In the situation according to 4h is the powder layer 21 optimally prepared so that the powder attachment step can take place. After that, the build platform 13 lowered by the measure of the desired next powder layer thickness, whereupon the above with reference to 4a -H explained sequence of the layer preparation can be run through again.

The basis of the 4a -H described movement may well be modified within the scope of the invention. Thus, a powder hardening step and a lowering step of the building platform 13 be inbetween before proceeding from the situation according to 4f the powder smoothing bar 47 towards the first reversal point 58 is moved back. In such a case, the powder supply, so the above as a residual amount 62 designated amount of powder be large enough to another powder layer 21 when painting over the construction platform 13 to prepare towards the first reversal point.

In the case of the concept pursued here, in each case a quantity of powder which has been displaced beyond the construction platform is to be skipped and during the return movement of the powder smoothing strip 47 back to the construction platform 13 If necessary, take a larger amount of powder, which is suitable for a variety of powder layers 21 sufficient, by means of Pulverglättungsleiste 47 be pushed back and forth.

According to another embodiment of the invention may also be an additional powder inlet point on the powder inlet 55 opposite side of the build platform 13 between the build platform 13 and the second reversal point be provided.

The in 4a -H illustrated movement of the powder smoothing bar 47 can also be modified so that the lowering step according to 4e not with every return movement of the powder smoothing bar 47 to the first reversal point 58 takes place, but only occasionally, after preparation of several layers 21 on the build platform. In such a case, although in between a possibly larger residual amount could 62 on powder between the build platform 13 and the second reversal point. This residual quantity 62 however, powder can be taken up again if occasionally the intermediate step according to 4e is inserted again.

Another possible variant in the movement sequence of the powder smoothing bar 47 is that the powder smoothing bar 47 starting from the situation according to 4d or according to the situation 4e omitting the lowering step immediately in the situation according to 4h is transferred, so that the lowering step takes place again when the Pulverglättungsleiste 47 on the return movement the first reversal point 58 has reached.

Basically, therefore, with the in 3 The device according to the invention can be followed the concept that the powder in the area between the reversal points 58 . 60 the powder smoothing bar 47 remains concentrated by the powder smoothing bar 47 is moved so that it can "jump over" in this area accumulated powder quantities.

During the irradiation process, a next dose of powder may already pass through the powder inlet 55 in the process room 9 for the preparation of the next layer of powder on the build platform 13 be encouraged. The powder is this from a at 57 connected external storage tank of the Pulereinlasstelle 55 fed, one below the process space floor 11 extending powder feed channel the powder inlet point 55 connects to the reservoir. By doing Powder feed channel is a screw conveyor rotatably received by a controlled electric motor 59 is driven for rotation to the powder from the reservoir out to Pulearllasstelle 55 zwangszufördern.

The processes of the powder layer preparation on the building platform 13 and the site-selective solidification by irradiation of the powder repeat each other until the desired shaped body 23 ( 2a . 2 B ) is completed. The leadership of the laser beam 27 during its scanning movement over the build platform 13 takes place in a known manner in accordance with Geometriebeschreibungsdaten of the molding in each case concerning the currently irradiated layer.

In 3 is another hole 61 in the process room floor 11 recognizable. This serves z. For example, excess powder from the process room floor 11 dissipate after completion of the molding. This can be done manually using the sealing gloves (not shown) at the access openings 19 done with a sweeping tool or the like.

In 3 has the smoothing slider 43 a pivotable in a certain horizontal plane base arm 65 , on which a height-adjustable support frame 67 the powder smoothing bar 47 is arranged. The support frame 67 is by spring arrangements 69 biased to the lowered position. A pneumatic cylinder (not shown) on the base arm 65 can be pressurized with gas to the holding frame 67 against the spring bias of the springs 69 relative to the base arm 65 and the process room floor 11 to raise. Thus, in the example, it is a pneumatic actuator for the controlled height adjustment of Pulverglättungsleiste 47 in front.

Alternatively, the actuator could but z. B. also be an electromagnetic actuator or possibly a hydraulic actuator or possibly a purely mechanical actuator. In the example of the 3 is only a small stroke of the support frame 67 and the attached powder smoothing bar 47 provided by a few millimeters. Of course, in alternative embodiments of the invention, the stroke may be adapted to the requirements.

5 shows a variant of the embodiment of 3 , Elements in 5 that their structure or / and effect elements in 3 correspond are marked with correspondingly the same reference numerals. In the embodiment according to 5 includes the powder layer preparation device 41 two powder smoothing strips 47 . 49 , The powder smoothing strips 47 . 49 limit between them a downwardly open space 53 in which the smoothing slider 43 Powder to building platform 13 can transport. The powder is introduced into the process space by means of the powder supply device 9 promoted, as already with reference to 3 was explained. The powder inlet opening 55 is located at a location between the build platform 13 and the in 5 shown reversal point of the smoothing slider bar 47 , More specifically, the powder inlet port is located 55 exactly under the gap 53 between the powder smoothing strips 47 . 49 when the smoothing slider 43 in the in 5 The first reversing position shown also includes a powder replenishing wait position of the smoothing slider 43 is. After feeding a metered amount of powder into the space 53 Control of the SLM device causes the smoothing slider 43 to, from the in 5 to pivot shown in the first reversal position in the second reversing position, so that in doing so from the trailing Pulverglättungsleiste 47 advanced powder to the build platform 13 arrives. The construction platform 13 is previously the measure of the desired powder layer thickness in its cylinder guide 33 been lowered. Because the smoothing bar 47 when painting over the construction platform 13 with its underside at the base level 51 of the process room floor 11 a smoothed powder layer of the desired thickness is produced. In the movement of the smoothing slider from the first reversal point to the second reversal point is the leading smoothing slider bar 49 in her raised state. It is on reaching the second reversal point on the process room floor 11 lowered, whereas the other Pulverglättungsleiste 47 from the process room floor 11 is lifted. Then the return movement of the smoothing slide is performed, in which now the leading Pulverglättungsleiste 47 remains in its raised state and the trailing Glättungsschieberleiste 49 Powder on the process room floor 11 can push around. Upon reaching the first reversal point then the Pulverglättungsleiste 47 lowered again and the powder smoothing bar 49 lifted again from the process room floor. In the case of such a two-armed smoothing slide, it is likewise achieved that a respective powder smoothing strip can provide residual powder on the process chamber bottom. In each case, this is the powder smoothing strip trailing during the current pivoting movement. The stroke control of the powder smoothing strips in 5 is done by the same means as the stroke control of the smoothing bar in 3 , namely preferably by means of a spring-biased pneumatic actuator.

Also for the embodiment according to 5 It goes without saying that alternative actuators for the stroke of Pulverglättungsleisten 47 . 49 can be provided.

It should also be pointed out that the smoothing slider of a device according to the invention may have, in alternative embodiments, instead of a pivoting arm, a linearly reciprocable holder for the powder smoothing strip or powder smoothing strips.

In 6 is a schematic plan views a-c another aspect of the invention illustrated in an additional embodiment, namely the aspect that the Pulverglättungsleiste 47 has a deviating from the rectilinear shape in plan view. In the example of the 6 is the powder smoothing bar 47 arched, so that they are with their convex side 70 can achieve a powder spreading effect, whereas with its concave side 72 can achieve a powder-collecting effect, depending on the direction of movement of the Pulverglättungsleiste 47 , In the snapshot according to 6a is the powder smoothing bar 47 at the first reversal point. It is located between the Pulverglättungsleiste 47 and building platform 13 the powder intake point 55 , Now powder at the powder inlet 55 introduced into the process space, then this powder can during the movement of the Pulverglättungsleiste 47 towards the second reversal point on the build platform 13 be distributed. The powder smoothing bar 47 is in its lowered state on the process room floor 11 , Shortly before reaching the second reversal point is the Pulverglättungsleiste 47 raised and above the previously with the convex side 70 advanced amount of residual powder 62 carried away. In the snapshot according to 6c This has already happened, leaving the powder smoothing bar 47 where it has been lowered back to the process room floor at the second reversal point. Starting from this situation then the Pulverglättungsleiste 47 moved back towards the first reversal point, with the concave side 72 the powder smoothing bar 47 now in the return movement, the amount of powder 62 merges into a narrower area. Such a curved powder smoothing bar 47 thus brings in the context of the invention very special advantages. The above-explained powder distribution and collection effect by a non-linear Pulverglättungsleiste 47 can z. B. also be achieved if this instead of the continuous arc shape shown a V-shape or the like. Has. In the context of the present application, the term arc should also such unsteady curved geometries, such. B. include the V-shape.

It should be noted that the relative height adjustment between the powder smoothing bar and the process room floor can also be made in other embodiments of the invention so that the process space bottom is moved vertically relative to the powder smoothing bar.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102004041633 A1 [0003]
• DE 10236907 A1 [0003]
• DE 19905067 A1 [0003]
• DE 10112591 A1 [0003]
• WO 98/24574 A1 [0003]

Claims (14)

Apparatus for the production of shaped bodies by layer-wise building up from material powder by location-selective solidification of the powder to coherent areas in accordance with geometry description data of the shaped body, comprising - a process space ( 9 ) with a process room floor ( 11 ), which is a base level ( 51 ) and a relatively height controlled by means of a controllable drive unit along a vertical platform platform construction platform ( 13 ) for the shaped body, - a powder layer preparation device for preparing a respective subsequently selectively to be solidified powder layer ( 21 ) on the build platform ( 13 ) and - a powder hardening device, which is used for site-selective solidification of powder last on the building platform ( 13 ) prepared powder layer ( 21 ) is activatable, wherein the powder layer preparation device ( 41 ) a powder supply device for providing powder in the process space ( 9 ) and a smoothing slider ( 43 ) with a powder smoothing strip ( 47 ) for distributing and smoothing the powder supply device in the process space ( 9 ) provided powder on the build platform ( 13 ), wherein the smoothing slider ( 43 ) with its powder smoothing strip ( 47 ) between two reversal points ( 58 . 60 ) with in plan view intermediate building platform ( 13 ) in the process room ( 9 ) is reciprocable to the Pulverglättungsleiste ( 47 ) in a desired powder layer thickness corresponding distance to that in the previous step on the build platform ( 13 ) site-selectively solidified powder layer ( 21 ) over the build platform ( 13 ), characterized in that the powder smoothing strip ( 47 ) in their movement between the reversal points ( 58 . 60 ) relative to the process room floor ( 11 ) controlled height adjustable. Apparatus according to claim 1, characterized in that the powder supply device one in particular at an outside of the process space ( 9 ) and a conveyor for conveying powder in the powder feed channel, in particular during the phases in which the powder solidification device for the site-selective solidification of powder last on the building platform ( 13 ) prepared powder layer ( 21 ) is activated, wherein the powder feed channel at least one between the building platform ( 13 ) and one of the reversals ( 58 . 60 ) of the powder smoothing strip ( 47 ) powder inlet point ( 55 ) opens into the process space to powder directly to the process room floor ( 11 ). Device for the production of moldings according to claim 2, characterized in that the powder smoothing strip ( 47 ) is height-adjustable so that it can be moved over the powder intake point ( 55 ) alternately from the base level ( 51 ) of the process room floor ( 11 ) or the base level ( 51 ) of the process room floor ( 11 ) is closely approximated. Device for the production of moldings according to one of the preceding claims, characterized in that the smoothing slide ( 43 ) one between the reversal points ( 58 . 60 ) movably guided arm on which the Pulverglättungsleiste ( 47 ) is arranged adjustable in height. Device for the production of moldings according to claim 4, characterized in that a pneumatic and / or electromagnetic and / or hydraulic actuator for the controlled height adjustment of the Pulverglättungsleiste ( 47 ) is provided. Device for the production of moldings according to one of the preceding claims, characterized in that a mechanical actuator is provided, which the height adjustment of the Pulverglättungsleiste ( 47 ) of the movement drive for the translational movement between the reversal points ( 58 . 60 ). Device for the production of moldings according to one of the preceding claims, characterized in that the smoothing slide ( 43 ) is controllable by means of a control device such that the powder smoothing strip ( 47 ) in the movements between the reversals ( 58 . 60 ) has a predetermined movement profile of the height adjustment movement. Device for the production of moldings according to one of the preceding claims, characterized in that the smoothing slide ( 43 ) another powder smoothing bar ( 49 ), which with the one powder smoothing strip ( 47 ) a space open to the process room floor ( 53 ) and that also the further powder smoothing strip ( 49 ) in their movement between the reversal points ( 58 . 60 ) relative to the process room floor ( 11 ) controlled height adjustable. Device for the production of moldings according to claim 8, characterized in that the powder smoothing strips ( 47 . 49 ) are independently adjustable in height. Apparatus according to claim 8 or 9, characterized in that the powder supply device is adapted to powder in the intermediate space ( 53 ) between the powder smoothing strips ( 47 . 49 ). Apparatus according to claim 8, 9 or 10, characterized in that the smoothing slide ( 43 ) is controllable by means of a control device such that the powder smoothing strips ( 47 . 49 ) in the movements between the reversals ( 58 . 60 ) are alternately raised or lowered, wherein the respective forward in the direction of movement Pulverglättungsleiste ( 47 . 49 ) while the trailing powder leveling bar ( 47 . 49 ) is lowered. Device according to one of the preceding claims, characterized in that the powder hardening device has an irradiation device with a radiation source, in particular a laser radiation source whose radiation is spatially selective to the construction platform ( 13 ) is to powder of each last prepared thereon powder layer ( 21 ) to remix or sinter into coherent areas. Apparatus according to claim 2 or any one of claims 3 to 12, within the scope of its recitation to claim 2, characterized in that the conveyor is controllable to produce a respective predetermined amount of powder for the preparation of a given number of powder layers ( 21 ) in the process room ( 9 ). Device according to one of the preceding claims, characterized in that each powder smoothing strip ( 47 . 49 ) in plan view has the shape of an arc.

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