DE102018215301A1 - Device and method for additively producing a three-dimensional object - Google Patents

Abstract

A manufacturing device (1) for the additive manufacturing of a three-dimensional object (2) by selectively solidifying a building material (13) in layers comprises a flow device for generating a gas stream (30) in the manufacturing device (1). The flow device comprises a flow modification element (32, 40) for introducing the gas stream (30) into the process chamber (3). The flow modification element (32, 40) comprises a body with a gas inlet side (41) and a gas outlet side (42) and a plurality of channels (43) which penetrate the body from the gas inlet side (41) to the gas outlet side (42), and the have an inlet opening (48) on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42) and are separated from one another by a wall, a channel cross-sectional area (44) of at least one channel (43) being perpendicular to an extension direction of the Channel, preferably the channel cross-sectional areas (44) of a majority of the channels, particularly preferably the channel cross-sectional areas (44) of all channels, in a first longitudinal section (152) of the channel or channels starting from the outlet opening (49) along the extension direction, wherein the first length section (152) is shorter than a total length (L) of the channel or channels between the Entry opening (48) and the outlet opening (49).

Description

The present invention relates to a device and a method for additively producing a three-dimensional object by applying layers and selectively solidifying a building material, in particular to a flow modification element for use in such a device and such a method.

Devices and methods of this type are used for example in rapid prototyping, rapid tooling or additive manufacturing. An example of such a process is known under the name “selective laser sintering or laser melting”. A thin layer of a powdery building material is repeatedly applied and the building material in each layer is selectively solidified by selective irradiation with a laser beam from points corresponding to a cross section of the object to be produced.

The energy input during selective solidification can result in impurities such as sprays, fumes, fumes, vapors and / or gases that spread in the process chamber. In addition, when using a powdery building material, contamination can result from the fact that powder or powder dust is whirled up in the process chamber. Contamination can have a negative impact on the manufacturing process, for example by absorbing, scattering or deflecting the scanning laser beam, settling on a coupling window for the laser beam or being deposited on a layer of building material. In order to meet high quality and efficiency requirements for the manufacturing process, such contaminants must be removed from the process chamber as quickly as possible.

To remove contaminants from the process chamber is from the WO 2015/144884 A1 a nozzle element is known through which a gas flow is introduced into the process chamber. The gas flow is discharged through a gas outlet on the side of the process chamber opposite the nozzle element, so that the gas flow is conducted over the construction field in which the building material is applied and selectively solidified. This gas flow, which is close to the construction site, removes the contaminants as close as possible to their point of origin, ie to the construction site, thus reducing the spreading of the contaminants into the process chamber.

The object of the present invention is to provide an alternative or improved device or an alternative or improved method for additively producing a three-dimensional object by applying layers and selectively solidifying a building material, with which in particular the removal of contaminants close to the building field can be improved.

This object is achieved by a manufacturing device according to claim 1, a method for additively manufacturing a three-dimensional object according to claim 11, a flow modification element according to claim 12, a flow device according to claim 13, the use of a flow modification element according to claim 14 and by a flow application method according to claim 15. Further developments of the invention are specified in the subclaims. The methods can also be further developed by the features of the devices below or specified in the subclaims, or vice versa, or the features of the devices and the methods can also be used among each other for further training.

• - einen Baubehälter zur Aufnahme des Aufbaumaterials,
• - eine oberhalb des Baubehälters vorgesehene Prozesskammer,
• - ein zwischen dem Baubehälter und der Prozesskammer vorgesehenes Baufeld,
• - eine Verfestigungsvorrichtung zum selektiven Verfestigen des Aufbaumaterials,
• - eine Beströmungsvorrichtung zum Erzeugen eines Gasstroms in der Herstellvorrichtung, wobei die Beströmungsvorrichtung ein Strömungsmodifikationselement zum Einleiten des Gasstroms in die Prozesskammer umfasst,

Das Strömungsmodifikationselement umfasst:

• - einen Körper mit einer Gaseintrittsseite und einer Gasaustrittsseite und
• - eine Mehrzahl von Kanälen, die den Körper von der Gaseintrittsseite zu der Gasaustrittsseite durchdringen, und die eine Eintrittsöffnung auf der Gaseintrittsseite und eine Austrittsöffnung auf der Gasaustrittsseite aufweisen und durch eine Wandung voneinander getrennt sind, wobei sich eine Kanalquerschnittsfläche zumindest eines Kanals senkrecht zu einer Erstreckungsrichtung des Kanals, vorzugsweise die Kanalquerschnittsflächen einer Mehrheit der Kanäle, besonders bevorzugt die Kanalquerschnittsflächen aller Kanäle, in einem ersten Längenabschnitt des Kanals bzw. der Kanäle ausgehend von der Austrittsöffnung entlang der Erstreckungsrichtung verringert/verringern, wobei der erste Längenabschnitt kürzer als eine Gesamtlänge des Kanals bzw. der Kanäle zwischen der Eintrittsöffnung und der Austrittsöffnung ist.

A manufacturing device according to the invention is used for the additive manufacturing of a three-dimensional object, the object being produced by applying a building material layer by layer and selectively solidifying the building material, in particular by supplying radiation energy, at locations in each layer which are assigned to the cross section of the object in this layer are scanned by scanning the points with at least one exposure area, in particular a radiation exposure area of an energy beam. The manufacturing device includes:

• - a building container for holding the building material,
• a process chamber provided above the construction container,
• a construction field provided between the construction container and the process chamber,
• a consolidation device for the selective consolidation of the building material,
• a flow device for generating a gas flow in the manufacturing device, the flow device comprising a flow modification element for introducing the gas flow into the process chamber,

The flow modification element includes:

• - a body with a gas inlet side and a gas outlet side and
• a plurality of channels which penetrate the body from the gas inlet side to the gas outlet side and which have an inlet opening on the gas inlet side and an outlet opening have on the gas outlet side and are separated from one another by a wall, a channel cross-sectional area of at least one channel perpendicular to an extension direction of the channel, preferably the channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, in a first length section of the channel or Channels starting from the outlet opening along the direction of extension reduced / reduced, the first length section being shorter than a total length of the channel or channels between the inlet opening and the outlet opening.

In the context of the application, the process chamber is understood to mean a cavity which is partially delimited by the construction field and preferably comprises the construction field for building the object. The construction field preferably forms part of a floor area on a lower side of the process chamber. The process chamber can be a substantially closed cavity with the exception of a gas inlet, which is formed by the flow modification element, and a gas outlet and optionally further gas inlets and / or gas outlets.

The flow modification element can be provided in a wall of the process chamber, which delimits the interior of the process chamber and thus surrounds the cavity. The flow modification element can have an extension perpendicular to the process chamber wall, for example be offset from the process chamber or protrude into the process chamber or be set back. The body of the flow modification element is preferably formed from a solid material.

A channel of the flow modification element forms a gas passage through which the gas can flow into the process chamber. During operation of the flow device, the gas enters the process chamber in the form of partial gas inlet flows, a partial gas inlet flow being introduced through one channel in each case. A channel is bounded on all sides by walls between openings on the gas inlet side and the gas outlet side, i. H. the gas runs inside the channels. The flow modification element is otherwise closed, i. H. the channels form the only gas-permeable openings through which gas can flow into the process chamber. The walls between adjacent channels prevent the gas from escaping from one channel into an adjacent channel. The flow modification element thus represents a three-dimensional region through which gas can be introduced into the process chamber, that is to say a gas inlet. The channels are also called main channels.

The direction of extension of a channel runs through the centers of gravity or center points of the channel cross-sectional areas of the channel, the channel cross-sectional areas being determined perpendicular to the direction of extension. The focus can e.g. B. in the case of a circle at the same time the center of the channel cross-sectional area. The direction of extension can be a straight line, a curve or a polyline, i. H. it includes the case of one or more curved or angled channels (ie can also be a curved line), that is to say denotes a “local direction” of a channel or channels. In other words, the direction of extension can include several spatial directions.

The term “channel cross-sectional area” is not limited to the cross-sectional area of the channel at the opening on the inlet or outlet side. Rather, the term “channel cross-sectional area” in the context of the present application can refer to a cross-sectional area of the channel at any point on the channel. For example, the channel or channels in the first length section can be designed as a diffuser. Because of the reduction in the cross-sectional area starting from the outlet opening in the direction of the inlet opening of the channel or channels, such a diffuser can also be referred to as an outlet or end diffuser.

The channel cross-sectional area is determined by a section plane through the respective channel, which is perpendicular to the respective direction of extension of the channel.

The reduction or reduction of the cross-sectional area of the channel means that the area of the cross-sectional area decreases along the direction of extension or expansion of the channel or channels. In operation of the flow modification element, ie with reference to the direction of gas flow through the channel or channels, the channel cross section is divergent over the first length section. The reduction or reduction of the channel cross-sectional area can, for. B. be continuous or discontinuous. A discontinuous reduction or reduction includes, for example, a section-wise or local expansion or enlargement of the channel cross-sectional area, while this is excluded in the case of a continuous reduction or reduction. The reduction or reduction can, for example, be stepped, ie the channel wall comprises one or more steps, ie at least two, preferably at least five, more preferably at least ten, even more preferably at least 20 steps. Alternatively, the reduction or reduction in the cross-sectional area of the duct can also be designed without steps.

A measure for a reduction or expansion of a channel cross-sectional area can be, for example, an angle and / or a slope and / or a curvature of a wall or a wall section of the respective channel with respect to the direction of extension of the channel. As an alternative or in addition, such a measure for the reduction or expansion can be a percentage or absolute value of the reduction or enlargement of the area.

The first length section is shorter than a total length of the channel or channels between the inlet opening and the outlet opening. The widening of the channel or channels in the gas flow direction thus begins at a point within the channel that is spaced from the inlet opening of the channel. In other words, a further length section of the channel (with a length greater than zero) is arranged upstream of the first length section of the channel or channels. It can be designed in any way to improve properties of the partial gas stream such. B. to influence speed, direction or turbulence before it experiences an expansion in the first length section.

The flow modification element can e.g. B. movable within the process chamber or stationary within the process chamber or stationary at the interface between the process chamber and a gas supply. For example, it can be arranged at the end of a gas line, which opens into the cavity of the process chamber through a recess in the wall of the process chamber.
The flow modification element can be designed to generate a global flow, ie at least one main flow, over the construction site and adjacent to the construction site, which completely covers the construction site. Alternatively, it can be designed to generate a local flow within the process chamber, which likewise runs adjacent to the construction field, but only partially or partially covers it.

The reduction in cross section from the gas outlet side, i.e. H. against the direction of flow means an expansion of the channel or channels in the direction of flow. In other words, the respective partial gas flow is also expanded before it flows through the outlet opening as a free jet into the process chamber. As a result, the speed of the respective partial gas flow in the first length section drops at least locally averaged. At the same time, a larger volume is flowed through in a directional manner and the tendency to turbulence in these “undefined” areas is reduced by the reduction in areas with no directional flow. The widening of the majority of the partial gas streams in the first length section therefore results in a more homogeneous total gas flow in the process chamber.

The narrowing of the cross-section is preferably not abrupt or abrupt, but is carried out over a certain distance, ie the length of the first length section, as a result of which friction losses which are generated by a collision of the gas molecules with the walls can be reduced or avoided. This can lead to a further improvement, in particular homogenization of the flow, ie a reduction in eddies in the flow within the process chamber. The locally and temporally fluctuating speed in a turbulent flow, on the other hand, can effectively remove contaminants, e.g. B. above the construction site, prevent. A homogeneous and as little turbulent flow as possible is therefore desirable in order to be able to achieve a good removal of impurities from the process chamber.
At least one channel, preferably a majority of the channels, more preferably all channels of the flow modification element preferably comprise or comprise a second length section, the channel cross-sectional area (s) of the channel or the channels in the second length section being / are essentially constant, and further preferred the second length section adjoins the first length section along the direction of extension.

The second length section, like the first length section, is shorter than an overall length or total length of the channel between the inlet opening and the outlet opening. The first and the second length section preferably do not overlap one another, that is to say are separated from one another. The first length section adjoins an end of the channel on the gas outlet side and the second length section preferably adjoins an end of the first length section which faces away from the gas outlet opening. The channel can be formed entirely from the first and the second length section or can comprise a further third length section, for example specified further below.

The at least one channel or channels thus preferably comprise at least a first divergent section, i. H. a section which has a cross-sectional constriction against the flow direction of the partial gas flow or a cross-sectional widening in the flow direction of the partial gas flow, and a second section with an essentially constant cross-section.

The term “essentially” implies that slight, for example production-related, slight deviations in the cross-sectional area of the duct are also included over the second length section.

The second length section is thus in the gas flow direction, i. H. upstream, before the first length section. It is therefore closer to the gas inlet side or gas inlet opening of the channel than the first length section and does not adjoin the gas outlet opening. It can, but does not necessarily have to adjoin the gas inlet opening. The channel cross-sectional area of the second longitudinal section is preferably identical to the minimum channel cross-sectional area of the first longitudinal section. A transition between the two longitudinal sections is thus as smooth as possible, i. H. smooth, or without steps and cracks. The second length section offers the advantage of reducing turbulence, in particular reducing the expansion of interfering flows within the partial gas flow, which are transverse or oblique to the gas flow direction through the channel, ie. H. are also directed transversely to the direction of extension of the channel or channels. Your maximum extent perpendicular to the direction of extension is based on the corresponding extent of the cross section, for. B. limited to a diameter of the channel or channels in the second length section.

As described above, the cross-sectional change in the first length section serves to widen the flow. In the event that the channel cross-sectional area of the second longitudinal section is identical to the minimum channel cross-sectional area of the first longitudinal section, the exit velocity of the gas from the channel on the gas outlet side of the flow modification element is largely determined by the size of the channel cross-sectional area of the channel in the second longitudinal section, i.e. . H. the area of the channel before the cross-sectional expansion (in the gas flow direction during operation of the flow modification element).

At least one channel, preferably a majority of the channels, more preferably all channels of the flow modification element preferably comprise or comprise a third length section which adjoins the inlet opening of the flow modification element, the channel cross-sectional area (s) of the channel or channels starting in the third length section decreased / decreased from the inlet opening along the direction of extension.

The reduction or reduction of the channel cross-sectional area in the third length section can, for. B. be continuous or discontinuous. A discontinuous reduction or reduction includes, for example, a section-wise or local expansion or enlargement of the channel cross-sectional area, while this is excluded in the case of a continuous reduction or reduction. The reduction or downsizing can, for example, be stepped, i. H. the channel wall comprises one step or more, i. H. at least two, preferably at least five, more preferably at least ten, even more preferably at least 20 stages. Alternatively, the reduction or reduction in the cross-sectional area of the duct can also be unstaged.

The reduction in cross section from the gas inlet side, i.e. H. in the direction of flow means a narrowing of the channel or channels in the direction of flow. The third length section thus forms a convergent channel section and can be designed as a confuser or nozzle. As a result, the respective partial gas flow is first “bundled” in its third direction along its flow direction before it is expanded again in the first length. The speed of the partial gas flow increases in the first length section, since here a pressure in the gas volume is converted into an increase in the speed of the gas volume. At the same time, the narrowing of the cross section upstream causes a pressure increase or a dynamic pressure in the feed line, which ensures homogenization and / or calming of the incoming gas stream upstream of the flow modification element. There can thus be an equalization of flow properties, which can have a positive influence on the quality of the partial gas flows in the channels of the flow modification element and can subsequently also favor a homogenization of the gas flow introduced into the process chamber by the flow modification element. For example, a more uniform or more uniform distribution of flow directions, flow velocities, volume flows and / or pressures can be achieved.

In connection with the first length section, the channel or channels can, for example, be shaped as a so-called “convergent-divergent nozzle”.

The third length section preferably adjoins the second length section along the direction of extension. The channel cross-sectional area in the second length section of the channel or the channels preferably corresponds to a minimum channel cross-sectional area in the first length section and / or in the third length section. This offers the advantage of stepless transitions between the walls and thus ensures an improvement in the flow properties through the respective channel or the respective channels led partial gas flows.

Particularly preferred is / are at least one channel, preferably a majority of the channels, more preferably all channels of the nozzle element formed only by the first, second and third length section. This means that a total length of the channel or channels results from a sum of these three length sections and that there are no further segments of the channel or channels that are not specified in more detail. The third length section accordingly extends between the gas inlet opening and the second length section of the flow modification element. Such a design of a channel or channels causes the gas to accelerate in comparison with its speed before entering the flow modification element (third length section), then a reduction in turbulence of the partial gas flow (second length section) and a renewed expansion, which, however, takes place under a The speed is reduced as evenly as possible and the greatest possible homogeneity takes place (first length section).

The effect of this cascade of means of flow formation therefore lies in a controlled acceleration of the process gas volume brought in and in the development of a flow in the process chamber or above the construction field, which comes as close as possible to the ideal of a laminar flow.

The shape of the channels, in particular the reduction in cross-sectional area in the third length section and / or the widening of the channels in the first length section, can be calculated in advance, for example, by means of a computer simulation in such a way that the desired flow properties (in particular a pressure difference between the gas inlet side and the gas outlet side and / or a counterpressure on the gas inlet side and / or an outlet velocity of the gas flow from the flow modification element) can be achieved if a gas is introduced into the process chamber through the flow modification element.

The channel cross-sectional area preferably has at least one channel, preferably a majority of the channels, particularly preferably all channels of the flow modification element, in at least one of the length sections, preferably in the three length sections, at least one simply axisymmetric, preferably point-symmetrical geometry.

A simply axially symmetrical channel cross-sectional area can be triangular, for example. Examples of point-symmetrical channel cross-sectional areas are an oval, a circle, a regular hexagon or a rectangle.

Alternatively or additionally, the channel cross-sectional areas of a majority of the channels, more preferably all channels of the flow modification element, preferably have the same geometric shape. If channel cross-sectional areas of different channels have the same geometric shape, this does not necessarily mean that they are also of the same size, i. H. have the same area.

Channels with symmetrical channel cross-sectional areas have the advantage over irregularly shaped channels, for example, that tapering or reducing the channel cross-sectional area over a length section is easy to implement in terms of construction and manufacturing technology.

The channel cross-sectional area (s) in the first length section preferably decreases or decrease according to a monotonous, more preferably strictly monotonous, falling function and / or according to a smooth function, the channel cross-section area (s) in the first length section particularly preferably decreasing according to a linear function or reduce.

Alternatively or additionally, the channel cross-sectional area (s) in the third length section preferably decrease or decrease according to a monotonous, more preferably strictly monotonous, falling function and / or according to a smooth function. The channel cross-sectional area (s) in the third length section is particularly preferably reduced or decreased according to a linear function. An example of such a reduction in the channel cross-sectional area is a conical confuser.

A reduction in the cross-sectional area of the duct “in accordance with a smooth function” is to be understood to mean that the entire wall area is free of kinks, ie. H. in particular is also designed to be stepless. For example, the walls of the channel or channels in particular have no discontinuities such as e.g. B. levels. An example of such a reduction in the cross-sectional area of the duct is a transition diffuser. In contrast to a step diffuser, it ensures a lower pressure drop and, due to less turbulence, a higher homogeneity of the flow. The reduction of the duct cross-sectional area according to a linear function means that the inclination of the entire wall surface or a longitudinal strip, i.e. H. Detail, the wall of the channel or channels over the entire first or third length section has the same angle relative to the direction of extension of the channel or channels.

Such a continuous reduction in cross-section can, for example, further improve the homogeneity of the flow; for example, turbulence can be reduced.

The channel cross-sectional area (s) can decrease in the first length section along a single direction transverse, preferably perpendicular, to the direction of extension. Alternatively, the channel cross-sectional area (s) can decrease in the first length section along at least two different directions transversely, preferably perpendicularly, to the direction of extension.

The channel cross-sectional area (s) can decrease in the third length section along a single direction transverse, preferably perpendicular, to the direction of extension. Alternatively, the channel cross-sectional area (s) can decrease in the third length section along at least two different directions transversely, preferably perpendicularly, to the direction of extension.

The reduction of the channel cross-sectional area along a single direction means a two-dimensional narrowing of the channel or channels. For example, the height of the channel or channels can be constant, while a distance between the side walls decreases over the corresponding length section. B. the distance between the side walls be constant and decrease the height of the channel. Analogously, a reduction in the cross-sectional area in two different directions means a two-dimensional narrowing of the channel or channels.

This provides various options for the design of the channels, for example.

Preferably, the direction of extension is straight, i. H. rectilinear, i.e. not curved, and the inlet opening and the outlet opening of at least one channel, preferably a majority of the channels, more preferably all channels of the flow modification element are each arranged and / or oriented in such a way that the direction of extension is determined by their respective centroid, i.e. h runs through both the center of gravity of the inlet opening and the center of gravity of the outlet opening. More preferably, the direction of extension of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element runs parallel to the construction field, and / or the directions of extension of the majority of channels, preferably all channels of the flow modification element run parallel to one another.

A straight direction of extension of the channels means that a locally and temporally averaged direction of a gas flowing through the inlet opening into the flow modification unit essentially corresponds to a locally and temporally averaged direction of a gas flowing out through the outlet opening from the flow modification unit, a sufficient to compensate for process-related fluctuations large averaging period is assumed.

Such a configuration of the flow modification element makes it possible, for example, to implement a tapering or reducing the channel cross-sectional area over a length section in a constructionally and technically simple manner. In addition, the channels of the flow modification element can be arranged in rows and columns, e.g. H. in the form of a matrix, as described below. Overall, for example, an effective use of the body of the flow modification element is possible.

The first length section preferably comprises at least 30%, more preferably at least 40%, even more preferably at least 50% of the total length of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element between the inlet opening and the outlet opening. Alternatively or additionally, an angle of inclination of the wall of the channel or channels relative to the direction of extension of the channel or channels in the first length section is preferably at least 1 °, more preferably at least 2 °, particularly preferably at least 3 ° and / or preferably at most 20 °, more preferably at most 10 °, particularly preferably at most 5 °.

The flatter the angle of inclination of the wall or of the tapering part of the wall can be selected in the first length section, the better is a partial gas flow against the wall or the less is the risk of the partial gas flow separating from the wall and the associated turbulence formation and as well as speed unevenness. This favors a low-turbulence flow pattern.

An angle of inclination of the wall of the channel or channels relative to the direction of extension of the channel or channels in the third length section is preferably at least 5 °, more preferably at least 10 °, particularly preferably at least 15 ° and / or at most 40 °, further preferably at most 30 °, particularly preferably at most 20 °. The flatter the angle of inclination of the wall or of the tapering part of the wall in the first length section, the lower falls the pressure loss caused by this section due to friction due to the impact or deflection of the gas molecules.

The total length of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element along the direction of extension is at least 5 cm, more preferably at least 10 cm, particularly preferably at least 15 cm.

The second length section preferably takes up at least 10%, more preferably at least 20% of a total length of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element between the inlet opening and the outlet opening. Alternatively or additionally, the length of the second length section along the direction of extension preferably corresponds to at least three times, more preferably at least five times, particularly preferably at least ten times the longest diagonal or the diameter of the channel cross-sectional area in the second length section.

Such a design of the second length section ensures an improved reduction of turbulence, in particular of disturbing currents transverse to the direction of extension of the respective channel.

A minimum channel cross-sectional area preferably comprises at least one channel, preferably a majority of the channels, particularly preferably all channels at most 90%, further preferably at most 60%, particularly preferably at most 30% of a maximum channel cross-sectional area of the channel or the respective channels. This makes it possible, for example, to generate a gas flow with particularly advantageous flow properties or to introduce it into the process chamber.

Preferably a minimum passage sectional area of the channel or channels at least 10mm ^2, more preferably at least 30mm ^2, even more preferably at least 50 mm ² and / or preferably at most 200 mm ^2, more preferably at most 150 mm ^2, still more preferably not more than 100mm. ² Alternatively or in addition, a maximum passage cross sectional area of the channel or channels at least 100mm ^2, more preferably at least 150mm ^2, more preferably still at least 200mm ^2, and / or preferably at most 800 mm ^2, more preferably at most 500 mm ^2, still more preferably not more than 300mm ² .

A value for the minimum channel cross-sectional area can e.g. B. can be selected depending on a cleanability of the channels of the flow modification element.

A value for the minimum and / or maximum channel cross-sectional area of the channel or channels in the first, second and third longitudinal section of the flow modification element is preferably selected as a function of a predetermined value for a gas outlet velocity with which one or all partial gas flows during operation from or Exit opening (s) of the flow modification element exits / exit into the process chamber, or depending on a predetermined value for a speed which has a total gas flow at a certain distance from the outlet opening (s) of the flow modification element into the process chamber, e.g. B. over the nearest edge of the construction site. The gas outlet speed can also be set depending on the material and z. B. 3 m / s.

According to a further preferred embodiment of the invention, the minimum channel cross-sectional area of at least one first channel is smaller than the minimum channel cross-sectional area of at least one second channel, the at least one first channel preferably being above the at least one second channel in the installed state of the flow modification element. The fact that the first channel in a vertical direction (perpendicular to the construction field) above, ie. H. further away from the construction site, staggering of the gas exit speeds from the channels can be achieved. In particular, this can result in the exit speed being further down, i. H. in the vicinity of the construction site is lower than above, which on the one hand can prevent the unsolidified construction material from being blown away and on the other hand can cause contaminants to be removed more quickly from the area above the construction site.

The channel cross-sectional area of the second longitudinal section preferably corresponds to a minimum channel cross-sectional area of the first longitudinal section and / or the third longitudinal section. This makes it possible to achieve a constant, i.e. H. to provide non-stepped transition between the length sections, which can further improve the flow properties, in particular the homogeneity of the partial flows.

In at least one channel, preferably in a majority of the channels, more preferably in all channels of the flow modification element, a channel cross-sectional area of the inlet opening essentially corresponds to a channel cross-sectional area of the outlet opening. So z. B. with parallel directions of extension of the channels a narrow staggering of the channels in Flow modification element can be selected and an area of the webs between the inlet openings or outlet openings can be reduced. This can, for example, reduce or weaken changes in direction of the gas flow, particularly on the gas inlet side, and reduce turbulence. In addition, this can reduce, for example, a pressure loss due to friction due to the flow modification element or a pressure difference between a space in front of the flow modification element and in a space after the flow modification element. Overall, this preferred embodiment therefore improves the flow properties.

A number of the channels of the flow modification element is preferably at least 50, preferably at least 100, particularly preferably at least 150 and / or at most 500, preferably at most 300, particularly preferably at most 200.

The flow modification element is preferably arranged in a cutout in a wall of the process chamber and a minimally surrounding rectangle around the outlet openings extends further preferably essentially starting from a plane of the construction field, i. H. the working level, extends upwards.

Alternatively, the flow modification element can be viewed from the working plane, i. H. the level of the construction site. This leads to a spacing of the partial gas flows let into the process chamber, as a result of which an undesirable tendency to turbulence due to an interaction of the partial gas flows with an unmoved or non-directional flow of process gas volume increases above the working level. It is therefore preferred that the outlet openings of the flow modification element are provided as close as possible, in particular directly adjacent to the working level or the level of the construction field.

As a synonym for the "minimal surrounding rectangle", d. H. a two-dimensional bounding box can apply to a minimal (imaginary) rectangle on the gas outlet side of the flow modification element, in which all outlet openings of the flow modification element lie.

The outlet openings can be arranged, for example, in one plane of the wall of the process chamber. The flow modification element can be arranged on an end piece of a gas supply line or can be fitted into the end piece, for which purpose the end piece can have a correspondingly dimensioned inner cross section. The inlet openings are correspondingly spaced from the process chamber and face the gas supply line from which process gas flows through them during operation.

The outlet openings of the flow modification element preferably extend to a height of at least 4 cm, more preferably at least 6 cm, even more preferably at least 8 cm and / or at most 30 cm, more preferably at most 20 cm, even more preferably at most 15 cm above the plane of the construction site. The flow modification element is thus, for example, in a construction site-near, ie. H. arranged lower height region of the process chamber, so that a gas flow introduced into the process chamber by the flow modification element essentially moves the process chamber in the lower, ie. H. can flow through the height range close to the construction site, which can lead to an efficient removal of contaminants directly to their point of origin.

The manufacturing device preferably further comprises a gas outlet for discharging process gas from the process chamber, the gas outlet preferably also being arranged on a side of the process chamber that is opposite the flow modification element. A gas flow can thus be generated within the process chamber between the gas inlet into the process chamber (with flow through the flow modification element) and the gas outlet from the process chamber, which adjoins a bottom surface of the process chamber or the construction field and locally on a lower region of a vertical extension of the process chamber is limited. Improved removal of contaminants that arise in the course of the solidification process can thus be achieved at least from a region of the process chamber above the construction site.

The channels of the flow modification element are preferably arranged in the form of a three-dimensional matrix and designed to generate a main flow over the construction field. More preferably, the matrix comprises at least two, even more preferably at least three, even more preferably at least five rows and / or at least five, even more preferably at least ten, even more preferably at least twenty columns.

A regular grid arrangement of the channels is understood as a matrix. The lines are preferably arranged parallel to the construction site and at the same distance from each other. The columns are preferably arranged perpendicular to the construction field and at the same distance from one another. This enables, for example, alignment with the working level or the level of the construction site. This can even out the Flow properties above the construction site or in an area surrounding the construction site.

The total area of the outlet openings of the flow modification element, which belong to the channels of the matrix, preferably takes up a portion of an area of a “minimally surrounding rectangle” which seamlessly frames the field of the outlet openings, which is at least 70%, preferably at least 80%, particularly preferably at least Is 90%. This embodiment offers the advantage of narrow webs between the outlet openings and thus small gaps between the partial gas flows. The smaller the gaps between the partial gas flows that flow from the individual outlet openings into the process chamber, the less turbulence and the higher the laminarity of the main flow.

Preferably, a maximum horizontal extension of the matrix of channels of the flow modification element corresponds to at least one extension of a closest side in the case of a rectangular construction field or at least one diameter in the case of a circular construction field, more preferably at least 110%, even more preferably at least 120% of the side length or the diameter . Alternatively or additionally, a maximum vertical extension of the matrix of channels of the flow modification element preferably corresponds to at most one half, more preferably at most one third, still more preferably at most one quarter, still more preferably at most one fifth of the maximum inner height of the process chamber.

The maximum vertical extent of the matrix preferably corresponds to a height range of the process chamber close to the construction field, i. H. a lower area of a maximum distance of the construction field from a process chamber ceiling. A “maximum distance” is the distance of the construction field from a highest point of the interior or cavity of the process chamber, i. H. to understand a maximum clear height of the process chamber, e.g. B. within an area of the process chamber (ie the cavity) adjacent to the construction site with a height extension of 10% or 15% of the maximum distance.

The maximum horizontal or vertical extension of the matrix of channels of the flow modification element can, for. B. using a minimally surrounding rectangle, d. H. a two-dimensional bounding box to determine the outlet openings of the channels on the gas outlet side.

Such a configuration of the flow modification element or dimension of the matrix can, for example, ensure that a large horizontal area of the construction field or the process chamber, in particular the entire surface of the construction field, is reliably overflowed or flowed through. This favors the effective removal of contaminants near the construction site, i.e. H. close to their place of origin, so that the impurities cannot spread or can only spread to a small extent further into the process chamber. It is thus possible, for example, to increase the precision of the local energy input during the selective consolidation and thereby to improve the quality of the object to be produced.

The flow modification element preferably comprises at least on one horizontally adjacent side of the channels at least one guide channel, preferably a plurality of guide channels for generating a guide flow over a floor of the process chamber next to the construction field, the guide channel or the guide channels the body of the flow modification element from the gas inlet side to the Penetrate gas outlet side and has / have an inlet opening on the gas inlet side and an outlet opening on the gas outlet side and are separated from one another by a wall.

More preferably, at least one guide channel, preferably a majority of the guide channels, particularly preferably all guide channels comprise a first guide channel length section which adjoins the gas inlet side and whose guide channel cross-sectional area decreases starting from the inlet opening along an extension direction of the guide channel. Even more preferably, the guide channel or guide channels comprise a second guide channel length section which adjoins the gas outlet side and whose guide channel cross-sectional area is essentially constant, with the guide channel or guide channels being particularly preferably through the first guide channel length section and the second Guide channel length section are formed.

Alternatively or additionally, the channels of the flow modification element are further preferably arranged in a three-dimensional matrix and the guide channel or the guide channels is or are arranged on a horizontally adjacent side of the three-dimensional matrix of channels.

The guide channels can thus be provided in particular without a length section (diffuser) widening in the flow direction. The lack of a diffuser in the guide channels ensures a higher exit velocity of the respective partial gas flows from the guide channels. The associated higher tendency to turbulence generally does not affect the quality of the main flow, since the leading flow does not flow over the construction site, but rather offset to the side. The leading flow can be a Lead main flow and / or shield any interfering flows from areas of the process chamber which are not directionally flowed. This can also improve the homogeneity of the main flow. The main flow is understood to be a flow that enters the process chamber from the ducts or main ducts, that is to say not the guide ducts, and which preferably flows essentially over the entire construction field, ie, flows over the construction field globally.

The direction of extension of the guide channels can run parallel to the directions of extension of the channels of the matrix or be angled, e.g. B. not on the construction site or on a gas outlet, but at an angle to the outside of the wall of the process chamber. In other words, the first guide channel length section preferably has a first extension direction and the second guide channel length section preferably has a second extension direction, the first and the second extension direction being further preferably each straight, and the first and the second extension direction being one of Include zero different angles to each other. This makes it possible, for example, obliquely outwards, i.e. H. at an outward angle to the main flow, to discharge leading flow into the process chamber.

The flow modification element preferably comprises at least one guide channel, preferably at least one column of guide channels, on both horizontally adjacent sides of the three-dimensional matrix of channels.

The guide channel cross-sectional area of the inlet opening of at least one guide channel, more preferably a plurality of the guide inlet channels, even more preferably all guide channels is larger than the channel cross-sectional area of the inlet opening of at least one channel, preferably a majority of the channels, further preferably all channels. In this way, for example, a guide flow can be achieved which has a larger volume flow per volume element flowed through than the main flow introduced through the channels.

The flow modification element preferably further comprises at least one guide element with at least one guide surface for guiding a gas flow in the process chamber at least in sections, the at least one guide element having a first end which is provided on the flow modification element on its gas outlet side, preferably with the first end of the guide element being gap-free is provided on the flow modification element. The first end preferably has a vertical dimension which corresponds to at least one vertical total extent of the outlet openings of the channels and / or the guide channels. Furthermore, the guide element preferably comprises a second end, which is spaced a distance from the outlet openings of the channels and / or the guide channels, for example by at least 1 cm, preferably by at least 5 cm, particularly preferably by at least 10 cm. The guide element preferably comprises a guide surface which faces a main flow flowing out of the channels into the process chamber during operation of the flow device and / or a guide surface which faces a guide flow flowing out of the guide channels during operation of the flow device. A direction in which the at least one guide surface extends is preferably matched to an extension direction of the second guide channel length section, the direction in which the at least one guide surface extends, more preferably by an angle of less than 20 °, even further preferably deviates less than 10 °, still more preferably less than 5 ° from the extension direction of the second guide channel length section, particularly preferably is essentially parallel to the extension direction of the second guide channel length section.

With such a guide element, it is possible, for example, to guide and / or shield a flow introduced into the process chamber by the flow modification element, in particular the above-mentioned main flow or guide flow, which can lead, for example, to an improvement in the flow properties of the flow, in particular a better one Homogenization of the flow.

At least two guide elements are preferably provided on the flow modification element, a first of the guide elements being provided on a first end of the flow modification element and a second of the guide elements being provided on a second end of the flow modification element, the first and the second end of the flow modification element being in a horizontal direction , d. H. parallel to the construction field when the flow modification element is mounted in the process chamber wall, are spaced apart from one another.

This makes it possible, for example, to provide a guide element for each of the two guide flows introduced into the process chamber described above, which can lead to an improvement in the flow properties of the guide flows.

• - Aufbringen eines Aufbaumaterials Schicht auf Schicht,
• - selektives Verfestigen des Aufbaumaterials, insbesondere durch Zuführen von Strahlungsenergie, an Stellen in jeder Schicht, die dem Querschnitt des Objekts in dieser Schicht zugeordnet sind, indem die Stellen mittels einer Verfestigungsvorrichtung mit mindestens einem Einwirkbereich, insbesondere einem Strahlungseinwirkbereich eines Energiestrahlbündels, abgetastet werden, und
• - Wiederholen des schichtweisen Aufbringens und selektiven Verfestigens , bis das Objekt fertiggestellt ist,

wobei das Aufbaumaterial in einem Baubehälter vorgesehen ist, oberhalb des Baubehälters eine Prozesskammer vorgesehen ist, und zwischen dem Baubehälter und der Prozesskammer ein Baufeld vorgesehen ist. Bei dem Verfahren wird zumindest zeitweise während der Herstellung des dreidimensionalen Objekts mittels einer Beströmungsvorrichtung ein Gasstrom in der Herstellvorrichtung erzeugt, wobei die Beströmungsvorrichtung ein Strömungsmodifikationselement zum Einleiten des Gasstroms in die Prozesskammer umfasst. Das Strömungsmodifikationselement umfasst:

• - einen Körper mit einer Gaseintrittsseite und einer Gasaustrittsseite und
• - eine Mehrzahl von Kanälen, die den Körper von der Gaseintrittsseite zu der Gasaustrittsseite durchdringen, und die eine Eintrittsöffnung auf der Gaseintrittsseite und eine Austrittsöffnung auf der Gasaustrittsseite aufweisen und durch eine Wandung voneinander getrennt sind, wobei sich eine Kanalquerschnittsfläche zumindest eines Kanals senkrecht zu einer Erstreckungsrichtung des Kanals, vorzugsweise die Kanalquerschnittsflächen einer Mehrheit der Kanäle, besonders bevorzugt die Kanalquerschnittsflächen aller Kanäle, in einem ersten Längenabschnitt des Kanals bzw. der Kanäle ausgehend von der Austrittsöffnung entlang der Erstreckungsrichtung verringert/verringern, wobei der erste Längenabschnitt kürzer als eine Gesamtlänge des Kanals bzw. der Kanäle zwischen der Eintrittsöffnung und der Austrittsöffnung ist.

A method according to the invention for the additive manufacturing of a three-dimensional object comprises the following steps:

• - Applying a building material layer by layer,
• - selective solidification of the building material, in particular by supplying radiation energy, at locations in each layer which are assigned to the cross section of the object in this layer, by scanning the locations by means of a consolidation device with at least one exposure region, in particular an exposure region of an energy beam, and
• - repeating the layer-by-layer application and selective consolidation until the object is finished,

wherein the building material is provided in a building container, a process chamber is provided above the building container, and a building field is provided between the building container and the process chamber. In the method, a gas flow is generated in the manufacturing device at least temporarily during the production of the three-dimensional object by means of a flow device, the flow device comprising a flow modification element for introducing the gas flow into the process chamber. The flow modification element includes:

• - a body with a gas inlet side and a gas outlet side and
• a plurality of channels which penetrate the body from the gas inlet side to the gas outlet side and which have an inlet opening on the gas inlet side and an outlet opening on the gas outlet side and are separated from one another by a wall, a channel cross-sectional area of at least one channel being perpendicular to an extension direction of the channel, preferably the channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, in a first length section of the channel or channels starting from the outlet opening along the extension direction, the first length section being shorter than a total length of the channel or the channel is between the inlet opening and the outlet opening.

It is thus possible, for example, to achieve the advantages mentioned above in relation to the manufacturing device in an additive manufacturing process.

A flow modification element according to the invention is used to introduce a gas stream into a process chamber of a device for additively producing a three-dimensional object, in particular into a process chamber of a manufacturing device described above. The flow modification element has a body with a gas inlet side and a gas outlet side and a plurality of channels which penetrate the body from the gas inlet side to the gas outlet side and which have an inlet opening on the gas inlet side and an outlet opening on the gas outlet side and are separated from one another by a wall , wherein a channel cross-sectional area of at least one channel perpendicular to an extension direction of the channel, preferably the channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, decreases / decreases in a first length section of the channel or channels starting from the outlet opening along the direction of extension , wherein the first length section is shorter than a total length of the channel or channels between the inlet opening and the outlet opening.

The flow modification element preferably comprises means for preferably releasably attaching the flow modification element to the manufacturing device or to its process chamber, e.g. B. a screw connection, clamping, magnetic fastening, etc. It is thus possible, for example, to provide such a flow modification element as an equipment and / or retrofit kit with which, in particular, a manufacturing device can be easily upgraded or retrofitted. The flow modification element is thus preferably designed to be detachable and / or exchangeable from the process chamber wall.

A flow device according to the invention is used for a production device for the additive production of a three-dimensional object by solidifying construction material in layers and comprises the flow modification element described above. This makes it possible, for example, to provide a flow device for equipping or retrofitting a manufacturing device.

An inventive use of a flow modification element is used to introduce a gas flow in a manufacturing device for additively manufacturing a three-dimensional object, in particular in a manufacturing device described above, wherein the flow modification element has a body with a gas inlet side and a gas outlet side and a plurality of channels that separate the body from the Penetrate gas inlet side to the gas outlet side, and which have an inlet opening on the gas inlet side and an outlet opening on the gas outlet side and are separated from one another by a wall, a channel cross-sectional area of at least one channel being perpendicular to an extension direction of the channel, preferably that Channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, in a first length section of the channel or channels starting from the outlet opening along the extension direction, the first length section being shorter than a total length of the channel or channels between the Entry opening and the exit opening is. It is thus possible, for example, to achieve the effects described above in relation to the manufacturing device even when using a flow modification element.

A flow method according to the invention is used to generate a gas flow in a process chamber of a manufacturing device for additively manufacturing a three-dimensional object, in particular a manufacturing device according to the invention described above, the flow method comprising at least one step of generating a gas stream by means of a gas supply device and a step of introducing the gas stream into the process chamber through a flow modification element described above.

• 1 ist eine schematische, teilweise im Schnitt dargestellte Ansicht einer Vorrichtung zum additiven Herstellen eines dreidimensionalen Objekts gemäß einer Ausführungsform der vorliegenden Erfindung,
• 2 ist eine schematische, teilweise im Schnitt dargestellte perspektivische Ansicht eines Strömungsmodifikationselements gemäß einer ersten Ausführungsform zur Verwendung in der in 1 gezeigten Herstellvorrichtung,
• 3 ist eine schematische Schnittansicht eines Kanals des in 2 gezeigten Strömungsmodifikationselements,
• 4 ist eine schematische Schnittansicht des in 2 gezeigten Strömungsmodifikationselements gemäß einer zweiten Ausführungsform in einer Ebene parallel zur x-y-Ebene und
• 5 ist eine vergrößerte Ansicht eines Ausschnitts der in 4 gezeigten Schnittansicht des Strömungsmodifikationselements.

Further features and advantages of the invention result from the description of exemplary embodiments with reference to the attached drawings.

• 1 FIG. 2 is a schematic view, partially in section, of a device for additively producing a three-dimensional object according to an embodiment of the present invention, FIG.
• 2nd FIG. 12 is a schematic perspective view, partly in section, of a flow modification element according to a first embodiment for use in FIG 1 manufacturing device shown,
• 3rd is a schematic sectional view of a channel of the in 2nd flow modification element shown,
• 4th is a schematic sectional view of the in 2nd Flow modification element shown according to a second embodiment in a plane parallel to the xy plane and
• 5 is an enlarged view of a portion of the in 4th shown sectional view of the flow modification element.

The following are with reference to 1 to 5 two different embodiments of the present invention are described. In the 1 The device shown is a laser sintering or laser melting device 1 . To build an object 2nd it contains a process chamber 3rd with a chamber wall 4th .

Below the process chamber 3rd is an open container 5 , which is also referred to as a construction container, with a container wall 6 arranged. In the container 5 is one in a vertical direction V movable carrier 7 arranged on which a base plate 8th attached to the container 5 closes down and thus forms its bottom. The base plate 8th can be one separate from the carrier 7 formed plate, which on the carrier 7 is attached, or it can be integral with the carrier 7 be educated. Depending on the construction material and process used, the base plate can be used 8th another build platform 9 be attached as a construction document on which the object 2nd is built up. The object 2nd but can also on the base plate 8th be built yourself, which then serves as a construction document.

Through the top opening of the container 5 is a working level 16 defined, the area of the working plane lying within the opening 16 that is used to build the object 2nd can be used as construction site 10th referred to as. The construction site 10th is between the container 5 and the process chamber 3rd intended. The working level 16 can also lead to the interior of the process chamber 3rd facing, ie upper, surface of a worktop, which in 1 is not shown. The worktop, not shown, also forms the bottom of the process chamber 3rd and surrounds the container 5 preferably on all sides. The working level 16 is a process chamber height from a ceiling 4a the process chamber wall 4th spaced. The process chamber height is also called the maximum clear height T referred to the process chamber, since a ceiling area of the process chamber has a non-uniform height level, e.g. B. with sloping ceilings.

In 1 is that in the container 5 on the build platform 9 object to be formed 2nd below the working level 16 shown in an intermediate state with several solidified layers, surrounded by unconsolidated building material 11 .

The laser sintering device 1 also contains a storage container 12th for a powdery building material that can be solidified by electromagnetic radiation 13 and one in a horizontal direction H movable coater 14 for applying the building material 13 within the construction area 10th . The coater preferably extends 14 across its entire direction to be coated.

Optionally, in the process chamber 3rd one in 1 Radiant heating, not shown, may be arranged for heating the applied building material 13 serves. For example, an infrared radiator can be provided as the radiant heater.

The laser sintering device 1 also includes a solidification device in the form of an exposure device 20th with a laser 21 , which is an energy beam in the form of a laser beam 22 generated by a deflection device 23 deflected and by a focusing device 24th via a coupling window 15 that in a blanket 4a the chamber wall 4th the process chamber 3rd is attached to the working level 16 is focused. The laser beam strikes in a radiation exposure area or an impact point or impact area (in 1 not shown) in the working level 16 on.

The laser sintering or laser melting device also contains 1 a gas supply duct 31 with a gas inlet element 32 and a gas discharge duct 35 with a gas outlet 34 to generate a gas stream 33 . The gas introduction element is described below with reference to 2nd , 3rd , 4th and 5 described in more detail. The gas outlet 34 can be from one or more openings in the process chamber wall 4th be educated. Alternatively, a further flow modification element at the gas outlet can also be used 34 be provided. The gas supply channel 31 and the gas discharge duct 35 are connected to a gas delivery device, not shown.

The gas inlet element 32 and the gas outlet 34 are on opposite sides of the construction site 10th and in a height area of the process chamber close to the construction site 3rd arranged. With a clear height T the process chamber, ie a maximum distance T the working level 16 or the construction site 10th from the process chamber ceiling 4a , the gas inlet element 32 and the gas outlet 34 for example within one to the construction site 10th adjacent area of the process chamber 3rd , which is a height extension of 10% of the clear height T includes, be arranged.

The gas inlet element 32 and the gas outlet 34 not to the working level 16 limit, but can also be spaced from this. The gas inlet element 32 and / or the gas outlet 34 can, for example, 2 cm or 5 cm above the working level 16 be provided.

A protective gas is preferably used as the gas, which does not undergo any chemical reaction with the building material (inert gas), depending on the building material used, for example nitrogen or argon.

The laser sintering device also contains 1 a control unit 29 , about which the individual components of the device 1 can be controlled in a coordinated manner to carry out the construction process. Alternatively, the control unit can also be attached partially or entirely outside the device. The control unit can contain a CPU, the operation of which is controlled by a computer program (software). The computer program can be stored separately from the device on a storage medium from which it can be loaded into the device, in particular into the control unit.

Various types of powder can be used as the building material, in particular metal powder, plastic powder, ceramic powder, sand, filled or mixed powder. Instead of powder, other suitable materials can also be used as the building material. The building material is preferably a metal powder. When using a metal powder as a building material, the occurrence of contaminants such. B. spatter, smoke, smoke, vapors and / or gases are particularly large, so that particularly good improvements in the manufacturing process or the quality and / or dimensional accuracy of the object to be produced can be achieved by the invention.

2nd shows a flow modification element 40 for use as a gas inlet element 32 in the in 1 process chamber shown 3rd . The flow modification element is preferably 40 formed as a one-piece component. It can e.g. B. by means of an injection molding process or an additive manufacturing process from any material, for. B. metal or plastic.

The flow modification element 40 is formed from a body of a solid material, in 2nd a cuboid body which, during operation of the gas supply device, is flush with the gas supply duct, which is cuboid at least in the end region 31 the device 1 (see 1 ) fits. The body is from a gas entry side 41 to a gas outlet side 42 towards a plurality of channels 43 , first guide channels 51 and second guide channels 52 permeated. A bounding box around the channels' cavities 43 and the master channels 51 , 52 corresponds to a cuboid with slightly smaller dimensions than the body. On the gas inlet side 41 point the channels 43 and the first and second lead channels 51 , 52 one entry opening each 48 (in 1 through the flow modification element 40 covered) on and on the gas outlet side 42 one outlet each 49 . The canals 43 , the first guiding channels 51 and the second guide channels 52 are bounded on all sides by walls (except at the entrance opening 48 and the outlet opening 49 ) and form the only gas-permeable connection from the gas inlet side 41 through the flow modification element 40 through to the gas outlet side 42 . The canals 43 , the first guiding channels 51 and the second guide channels 52 extend in a longitudinal direction over a length L , wherein the longitudinal direction of the flow direction of the gas through the flow modification element from the gas inlet side 41 to the gas outlet side 42 corresponds. Preferably is the longitudinal direction of all channels 43 , further preferably also at least in sections that of the first and second guide channels 51 , 52 , identical, ie the channels are parallel to each other in the flow modification element 40 arranged.

Laterally, ie transversely to the direction of flow of the gas through the flow modification element from the gas inlet side 41 to the gas outlet side 42 , the flow modification element extends 40 from a first end 45 to a second end 46 (only in 2nd shown). Preferably at the ends 45 , 46 the flow modification element fasteners 47 provided for fastening the flow modification element in the process chamber, for example on the process chamber wall 4th . The canals 43 are along a width B along the flow modification element 40 between the ends 45 and 46 of the flow modification element is provided, ie a maximum distance between the first end 45 closest channel and one the second end 46 the closest channel corresponds to the width B . The width is preferred B of the flow modification element to an extension of the construction field 10th in a direction parallel to the width B adapted, for example to a dimension of an adjacent construction site side of a rectangular construction site or a diameter of a circular construction site. Here is the width B preferably greater than the corresponding extension of the construction field, in particular at least 110%, more preferably at least 120% of this extension.

Perpendicular to the length L of the channels 43 and perpendicular to the width B the flow modification element 40 the flow modification element extends over a height or is the channels 43 and preferably also the guide channels 51 , 52 arranged over a height section, which (r) in 2nd is not fully shown due to the cut representation. This height or this height section is preferably essentially identical to the height of the lower or near construction field height range in which the gas inlet element 32 and the gas outlet 34 (see 1 ) are provided, for example 10% of the clear height T.

• - die x-Achse ist parallel zur Längsrichtung der Kanäle 43,
• - die y-Achse ist parallel zur Breite B des Strömungsmodifikationselements und
• - die z-Achse ist parallel zur Höhe des Strömungsmodifikationselements.

The axes of a Cartesian coordinate system are defined as follows:

• - The x-axis is parallel to the longitudinal direction of the channels 43 ,
• - The y-axis is parallel to the width B of the flow modification element and
• - The z-axis is parallel to the height of the flow modification element.

The canals 43 are preferably as in 2nd shown, with respect to the yz plane next to each other and regularly spaced apart in rows and columns, ie in the form of a three-dimensional matrix, in the flow modification element 40 intended. The rows are of channels 43 in the installed state of the flow modification element 40 preferably parallel to the construction site 10th arranged. For example, the matrix can have five rows and 21 Columns of channels 43 include. The lead channels 51 , 52 are in the y-direction to the side of the channels 43 arranged, that is on a horizontally adjacent side of the channels 43 , ie the first guide channels 51 are between the first end 45 the flow modification element 40 and the channels 43 provided and the second guide channels 52 between the second end 46 the flow modification element 40 and the channels 43 . The first guiding channels 51 are arranged one below the other in a first column of guide channels and the second guide channels 52 in a second column of lead channels. For example, the first and the second column of guide channels each comprise five guide channels 51 respectively. 52 . The number of routing channels in a column is preferably identical to the number of rows of channels 43 . Alternatively, at least one end of the flow modification element 40 several, for example two, columns of guide channels can also be provided.

In operation the gas delivery device (see below) is through the channels 43 a main flow (or become partial flows of the main flow) into the process chamber 3rd initiated, which is why the channels 43 are also referred to as main channels or main inlet channels, and through the first and second guide channels 51 , 52 each becomes a leading flow (or partial flows of the leading flow) into the process chamber 3rd initiated.

The canals 43 and the lead channels 51 , 52 each have a channel cross-sectional area in the yz plane, ie perpendicular to their longitudinal direction 44 on which at the in 2nd The embodiment shown has a square or rectangular shape. A maximum dimension of the duct cross-sectional area 44 , for example a diameter or a diagonal of the channel cross-sectional area 44 , is preferably less than the length L of the channels. According to the invention, the channel cross-sectional areas vary 44 of the channels 43 and the master channels 51 , 52 at least in sections over the length L of the channels, ie the channel cross-sectional area of a channel 43 or a lead channel 51 , 52 is at least in sections over the length L of the channel or the master channel is not constant. This cross-sectional area change is described below with reference to 3rd and 4th first for the channels 43 and then for the master channels 51 , 52 described in more detail. 3rd shows a section through a channel 43 along the x direction, ie along the longitudinal direction of the channel. The cutting plane can be parallel to the xy Be plane or parallel to the xz plane. 4th shows a section through the entire flow modification element 40 parallel to the xy plane, with the walls between the channels 43 or the guide channels 51 , 52 are marked with slashes through hatching.

How from 3rd and 4th the channel is visible 43 divided into three longitudinal sections in the longitudinal direction: a first longitudinal section 152 to the gas outlet side 42 the flow modification element 40 adjacent, a third section 151 that to the gas inlet side 41 the flow modification element 40 adjacent, and one between the first length 152 and the third length section 151 lying second length section 153 . The first length 152 extends over a first length c along the longitudinal direction of the channel 43 , the second length segment 153 extends over a second length b along the longitudinal direction of the channel 43 and the third length 151 extends a third length a along the longitudinal direction of the channel 43 . The three length sections are lined up without gaps, so that the sum of the three lengths a , b , c the total length L of the channel 43 corresponds to: L = a + b + c, ie each of the three lengths 152 , 153 , 151 is shorter than the total length L of the channel 43 . In 3rd are the first length c , the second length b and the third length a one third of the total length L of the channel 43 . Preferably the first length c of the first section 152 at least greater than the third length a of the third length section 151 , as in 4th shown; for example, the first length c can be 56% of the total length L, the second length b can be 25% of the total length L and the third length a can be 19% of the total length L be. The different length dimensions of the three length sections 151 , 152 , 153 and correspondingly different angles of inclination of the walls in the first and third longitudinal sections form a difference between the two in 2nd / 3 and 4th / 5 shown embodiments of the flow modification element 40 .

The channel points perpendicular to the longitudinal direction 43 a diameter d. The diameter d increases in the third length section 151 of an inlet-side diameter dein on the gas inlet side 41 in the longitudinal direction, ie decreases, down to a minimum diameter d _min , which at the end of the third section 151 , ie at the transition to the second length section 153 , is achieved. In the third section 151 adjacent second section 153 has the diameter d of the channel 43 a substantially constant value of d _min , which is the minimum diameter of the third length section 151 at the transition between the two lengths. In the second section 153 adjacent first length section 152 takes the diameter d in the longitudinal direction to the gas outlet side 42 of the flow modification element again, ie it increases from the minimum diameter d _min at the transition between the second and the first length section to an outlet-side diameter d _out on the gas outlet side 42 the flow modification element 40 . In other words, the diameter d of the channel increases 43 from the gas outlet side 42 in the longitudinal direction, ie decreases, and reaches at the transition to the third length section 153 the minimum diameter d _min .

The minimum diameter dmin can be, for example, 5 mm (ie with a square channel cross-sectional area, a minimum channel cross-sectional area of 25 mm ² ) and the maximum diameter dmax, which is on the gas inlet side 41 and / or the gas outlet side 42 is achieved, that is, d _max = d _and / or d _max = d _from, for example, can be 15 mm (ie with a square channel cross-section surface has a maximum passage cross sectional area of 225 mm ^2). The second length b is preferably the second length section 153 a multiple, for example ten times, of the diameter d in the second length section 153 , ie the minimum diameter dmin.

The reduction in diameter d in the third length section 151 and the reduction in diameter d in the first length section 152 is preferably designed according to a monotonous, in particular strictly monotonous, and smooth function and particularly preferably according to a linear function, as in 3rd shown. The angle of inclination γ the wall of the canal 43 in the first length segment 152 relative to the longitudinal direction can be, for example, 4 °, ie the first longitudinal section 152 has an opening angle of 8 °.

As mentioned above, the diameter may vary d of the channel 43 both the diameter in the y direction and the diameter in the z direction. The diameter d can also be both in y - as well as in e.g. -Direction along the length L of the channel 43 decrease or enlarge. By changing the diameter d along the longitudinal direction of the channel 43 the channel cross-sectional area also changes 44 of the channel in the longitudinal direction of the channel. In particular, the cross-sectional area of the duct is reduced 44 over the third section 151 starting from the gas inlet side 41 along the longitudinal direction (towards the gas outlet side 42 ) and over the first length 152 starting from the gas outlet side 42 along the longitudinal direction (towards the gas inlet side 41 ). In other words, the cross-sectional area of the duct increases over the first Length section 152 along the longitudinal direction towards the gas outlet side 42 . That through the channel 43 flowing gas therefore first passes the tapering third length 151 , ie a section designed as a confuser or nozzle, then the second longitudinal section 153 with a substantially constant cross-sectional area of the duct and then the widening first longitudinal section 152 , ie a section designed as a diffuser. The channel cross-sectional area preferably corresponds to this 44 the entrance opening 48 essentially the channel cross-sectional area 44 the outlet opening 49 .

The lead channels 51 , 52 are discussed below with reference to 4th described. The leading channel cross-sectional area of the leading channels 51 , 52 , what a 4th also by the diameter d 'of the guide channels 51 , 52 in y -Direction is shown, varies at least in sections along the longitudinal direction of the guide channels 51 , 52 . The lead channels 51 , 52 point each, analogous to the third length section 151 of the channels 43 , a first one, to the gas inlet side 41 subsequent leading channel length section 53 which is designed as a nozzle, ie a first guide channel length section 53 , in which the leading channel cross-sectional areas of the leading channels 51 , 52 starting from the gas inlet side 41 towards the gas outlet side 42 reduce. The guide channels also point 51 , 52 a second one each, to the gas outlet side 42 subsequent leading channel length section 54 which has a substantially constant guide channel cross-sectional area and preferably the minimum channel cross-sectional area of the first guide channel length section 53 corresponds to the transition between the first and second guide channel length section. The second leading channel length section 54 runs at an angle α respectively. α ' from Z. B. 150 ° to the first guide channel length section 53 , so that a (local) direction of extension of the guide channels 51 , 52 over the length L of the guide channels 51 , 52 varies across the board. The second guide channel length sections thus run 54 at an angle β respectively. β ' to a vertical S on the channel cross-sectional area of the outlet opening 49 of the master channels 51 , 52 .

The guide channels preferably comprise 51 , 52 no further guide channel length sections, ie they are completely formed by the first and second guide channel length sections. At the in 3rd and 4th shown flow modification element 40 the first guide channels differ 51 and the second guide channels 52 in the angles α and α ' that the second leading channel length sections 54 with respect to the first guide channel length section 53 form, or in the angles β and β ' . Alternatively, the angles α and α ' (including the angles β respectively. β ' ) and thus the first and second guide channels also be identical, so that the flow modification element 40 is symmetrical.

The lead channels 51 , 52 are therefore without the first (diffuser-shaped, ie divergent) length section of the channels 43 formed in which the guide channel cross-sectional area to the gas outlet side 42 enlarged towards. The guide channels thus point 51 , 52 on the gas outlet side 42 the flow modification element 40 one by a factor, for example 2nd or 3rd smaller (guide) duct cross-sectional area than the ducts 43 . As a result, this has from the lead channels 51 , 52 into the process chamber 3rd process gas flowing into it during operation of the gas delivery device and in the device 1 attached flow modification element 40 a greater flow rate compared to the flow rate out of the channels 43 escaping gas.

The guiding channel cross-sectional area is preferably the entry opening 48 of the master channels 51 , 52 , ie the leading channel cross-sectional area of the leading channels 51 , 52 on the gas inlet side 41 , larger than the channel cross-sectional area of the inlet opening 48 of the channels 43 , ie larger than the channel cross-sectional area of the channels 43 on the gas inlet side 41 . This results in a larger volume flow per volume element flowing through the guide channels during operation 51 , 52 into the process chamber 3rd introduced guide flow achieved.

The fact that the second guide channel length sections 54 at an angle β respectively. β ' to the vertical S on the leading channel cross-sectional area 44 the outlet opening 49 of the master channels 51 , 52 run, occurs in the operation of the gas delivery device and in the device 1 attached flow modification element 40 the gas at an angle β respectively. β ' to the vertical S from the guide channels 51 , 52 out. From the channels 43 on the other hand, the gas occurs during operation and with the flow modification element installed 40 on the other hand, essentially perpendicular to the channel cross-sectional area 44 the outlet opening 49 of the channels 43 and the master channels 51 , 52 , ie parallel to the vertical S , from the flow modification element 40 out.

This also includes in 2nd , 4th and 5 shown flow modification element 40 a first guiding element 61 and a second guide element 62 on the gas outlet side 42 the flow modification element 40 . The first guide 61 and the second guide 62 can be formed, for example, as thin sheets. The guiding elements 61 , 62 are preferably gap-free on the gas outlet side 42 the flow modification element 40 intended. Each of the guiding elements 61 , 62 has a height extension in the z direction, preferably the height or height extension a column of channels 43 and / or guide channels 51 , 52 corresponds, and extends in a second direction perpendicular to its vertical extent by a length f between a first one, on the gas outlet side 42 the flow modification element 40 intended end 63 and a second end 64 (only in 5 for the first guiding element 61 shown). The guide elements point in the third direction perpendicular to the second direction and to the vertical extent 61 , 62 a thickness that is several times smaller than the height extension and the length f . Thus, the guiding elements 61 , 62 essentially consisting of two planes, ie planes, and guide surfaces parallel to each other in pairs 65 , 66 educated. In 2nd are the guiding surfaces 66 each through the guide elements 61 , 62 covered.

The first guide 61 is horizontal, ie in the y direction, to the side or next to the first column of the guide channels 51 on the the canals 43 opposite side of the first column of guide channels 51 arranged and the second guide element 62 is horizontal, ie in the y direction, to the side or next to the second column of the guide channels 62 on the the canals 43 opposite side of the second column of guide channels 52 arranged.

The guiding surfaces 65 are on the guiding elements 61 , 62 provided that at in the device 1 attached flow modification element 40 and in operation of the gas delivery device (not shown) through the guide channels 51 , 52 leading streams (not shown) flowing into the process chamber are facing. The guiding surfaces 66 are respectively on the side of the guide element facing away from the guide flow 61 , 62 intended.

The guiding elements 61 , 62 are preferably so on the flow modification element 40 arranged that they stand out from their first end 63 (see 5 ) to its second end 64 (see 5 ) each extend parallel to a direction in which gas during operation of the gas delivery device and in the device 1 built-in flow modification element 40 through the respective master channels 51 , 52 flows into the process chamber. In other words, the guiding elements 61 , 62 or their guiding surfaces 65 , 66 preferably parallel to the respective direction of extension of the second guide channel length section 54 intended. This means that the first guide 61 or its guiding surfaces 65 , 66 is preferably arranged at an angle β to the vertical S and the second guide element 62 or its guiding surfaces 65 , 66 at the angle β ' to the vertical S is or are arranged.

In operation of the laser sintering or laser melting device described above 1 becomes the carrier for the application of a powder layer 7 lowered by a height that corresponds to the desired layer thickness. The coater 14 first drives to the storage container 12th and takes a sufficient amount of the building material from it to apply a layer 13 on. Then he drives across the construction site 10th , brings powdered building material there 13 onto the building base or an existing powder layer and pulls it out into a powder layer. The application takes place at least over the entire cross section of the object to be produced 2nd , preferably over the entire construction site 10th , that is through the container wall 6 limited area. The powdered construction material is optional 13 heated to a working temperature by means of a radiant heater (not shown).

Then the cross section of the object to be manufactured 2nd from the laser beam 22 scanned so that the powdery building material 13 is solidified at the points corresponding to the cross section of the object to be manufactured 2nd correspond. The powder grains are partially or completely melted at these points by means of the energy introduced by the radiation, so that after cooling they are connected to one another as solid bodies. These steps are repeated until the object 2nd is completed and the process chamber 3rd can be removed.

While building the object in layers 2nd becomes a gas through the gas supply channel at least temporarily by the gas delivery device, not shown 31 and the flow modification element 32 respectively. 40 into the process chamber 3rd initiated and through the gas outlet 34 and the gas discharge duct 35 out of the process chamber again 3rd led out or sucked out of this, so that a gas flow 33 in the process chamber 3rd is generated, which is above the working level 16 at least along the construction site 10th flows. The gas flows in the form of partial gas inlet flows from the flow modification element 40 into the process chamber 3rd , being on the gas outlet side 42 the flow modification element 40 from every channel 43 and from every lead channel 51 , 52 a partial gas inlet stream flows out. The one from the channels 43 escaping gas inlet partial flows form a main flow and that from the guide channels 51 , 52 outflowing gas inlet partial flows form a guide flow (not shown in the figures).

The one through the matrix of channels 43 shaped main gas stream points at least immediately after it emerges into the process chamber 3rd a correspondingly substantially rectangular cross section.

The flow modification element 32 respectively. 40 is preferably on or outside the process chamber 3rd arranged that its gas outlet side 42 essentially flush with the Inside of the side wall of the process chamber 3rd is provided (not shown in the figures). The flow modification element can e.g. B. may be arranged in a recess in the wall of the process chamber. A minimally surrounding rectangle around the outlet openings 49 the flow modification element 40 preferably extends essentially from a level of the construction site 10th upwards.

The following applies to the main flow: Through the above in relation to 3rd and 4th described narrowing cross-sectional area in the third longitudinal section 151 of the channels 43 the flow modification element 40 the pressure in the flow upstream of the flow modification element increases 40 , which leads to a homogenization of the flow or a more uniform distribution of the flow properties. The exit velocity of the gas flow 33 from the flow modification element 32 , 40 depends on the size of the cross-sectional area of the duct 44 of the channels 43 , among other things on the gas outlet side 42 the flow modification element 40 : The larger the cross-sectional area of the duct, the smaller the average outlet velocity of the gas inlet partial flow emerging from this duct can be for a given mass flow. The smaller the cross-sectional area of the duct, the greater the exit velocity of the partial gas inlet stream emerging from this duct. A total pressure difference in the gas between the gas entry side 41 and the gas outlet side 42 of the flow modification element is, among other things, dependent on the pressure increase in the third length section 151 and the pressure drop in the first length section 152 .

The leading flow is a flow that is generated to the side of the main flow in the process chamber, in particular over a bottom region of the process chamber outside the construction field or next to the construction field. The guide flow thus serves to shield and / or guide the main flow, as a result of which the flow properties of the main flow can be improved, for example. The guide flows preferably flank the main flow at least in sections.

The leading flow (s) occurs at the angle β respectively. β ' to the main flow direction of the main flow or to the perpendicular S from the flow modification element 40 out. The angle β respectively. β ' is preferably chosen so that it influences the guide flow z. B. taken into account by interfering or secondary flows occurring in the process chamber, so that the guide flows in their further flow course flow essentially parallel to the main flow, ie essentially along the main flow direction of the main flow.

The guiding elements 61 , 62 serve at least in sections to guide or guide the guide currents and / or to shield the guide currents, e.g. B. against interference currents. As an alternative or in addition, the guide elements serve at least in sections for guiding or guiding interfering flows. The directional stability and effective distance of the leading flow can thus be improved.

In the 2nd to 4th shown channels 43 and guiding channels 51 , 52 each have a square or rectangular channel cross-sectional area 44 perpendicular to their longitudinal direction, ie in the yz plane. The channel cross-sectional areas of the channels can, however, also have a different shape, for example a round or oval or hexagonal shape. In general, the channel cross-sectional areas can have any shape. The channel cross-sectional areas preferably have a symmetrical shape, in particular a simply axially symmetrical shape, preferably a point-symmetrical shape. The channels do not have to be arranged in the form of a matrix of rows and columns. For example, adjacent rows and / or columns can also be arranged offset from one another, or the channels can be arranged in any other arrangement. In the figures, the channel cross-sectional change is the channels 43 and the guide channels are each linear and continuous or continuous, ie not abrupt. Alternatively, the change in the cross-section of the duct can also be made in a stepped manner, ie the walls of the ducts 43 and / or the guide channels 51 , 52 each have at least one level.

Furthermore, the in 2nd shown channels 43 the flow modification element 40 identically designed (with the exception of possibly differently designed channels at the ends 45 , 46 the flow modification element). The canals 43 However, they can also be designed at least in part differently, in particular they can differ in the size and / or shape of their channel cross-sectional areas. The gas can also be passed through only a portion of the channels during operation in order to control the flow of the gas. For this purpose, for example, part of the channels of the flow modification element can be covered, preferably on the gas inlet side 41 . This can be done manually, e.g. B. by masking or covering and / or a slider can be provided as an aperture device. Such a slide can also be moved by motor, which in turn can be done by the control unit 29 can be controlled.

In particular, channels can be provided which differ in the size of their channel cross-sectional areas 44 in the second section 153 or in areas of the channels 43 with the respective minimum channel cross-sectional area of the flow modification element 40 differentiate from each other. This makes it possible to provide partial gas inlet flows with different outlet speeds. In particular, the exit velocity of the gas inlet partial flows can start from that of the construction site 10th facing side of the flow modification element 40 be increasingly set upwards, so that the lower gas inlet partial flows close to the construction field have a lower exit speed than the gas inlet partial flows remote from the construction field. This can be realized in that the channel cross-sectional areas of the channels on the gas outlet side 42 the flow modification element 40 from below (ie the side of the flow modification element close to the construction field) upwards (ie towards the process chamber ceiling 4a) get smaller.

The length of the first, second and / or third length section of a first channel or guide channel can also deviate from the length of the respective length section of a second channel or guide channel. However, the total length L of the channel or guide channel is preferably the same for all channels and guide channels of the flow modification element. Furthermore, the channels 43 can also be provided without the second (middle) length section. Furthermore, not all channels have to 43 the flow modification element 40 which have three described length sections, it is also possible, for example, to provide channels which have only one or two of the described length sections.

In the above with reference to 2nd to 5 Embodiment of the flow modification element described run the channels 43 straight from the gas inlet side 41 to the gas outlet side 42 the flow modification element 40 . The same applies to the first guide channel sections 53 of the master channels 51 , 52 . However, the invention is not restricted to straight-line channels or length sections or guide channel length sections. For example, the channels and / or guide channels can also be curved. To take this case into account, the more general term “extension direction” is used in the application instead of the term “longitudinal direction”. The direction of extension is defined by the centers of gravity of the channel cross-sectional areas (in the case of a circular cross-section, the center of the channel cross-sectional area is identical to the center of gravity) and can also be a curved line. The direction of extension does not have to correspond to a single spatial direction, but rather reflects the course of the channels or guide channels. The first, second and third lengths of the channels 43 which above regarding 3rd and 4th have been described, line segments of the extension direction can then likewise be correspondingly curved or angled relative to one another. The same applies to the leading channel lengths 53 , 54 of the master channels 51 , 52 .

The flow modification element described above 40 can also be provided without the guide channels or only on one side with guide channels, for example only with the first guide channels 51 or only with the second guide channels 52 be provided. Furthermore, the flow modification element 40 even without the guiding elements 61 , 62 be provided and / or such guide elements for those from the channels 43 emerging main flow can be provided.

The process chamber 3rd and the gas conveying device can also be used as a flow device for the laser sintering or laser melting device 1 be provided, in particular as an equipment or retrofit kit for equipping or retrofitting the device 1 . Alternatively, or in addition, the above may be related to 2nd to 5 Flow modification element described as an equipment or retrofit kit for equipping or retrofitting the device 1 be provided.

Even if the present invention has been described with the aid of a laser sintering or laser melting device, it is not restricted to laser sintering or laser melting. It can be applied to any method for the generative production of a three-dimensional object by applying layers and selectively solidifying a building material.

The imagesetter can comprise, for example, one or more gas or solid-state lasers or any other type of laser such as laser diodes, in particular VCSEL (Vertical Cavity Surface Emitting Laser) or VECSEL (Vertical External Cavity Surface Emitting Laser), or a row of these lasers. In general, any device can be used as an imagesetter with which energy as wave or particle radiation can be selectively applied to a layer of the building material. Instead of a laser, for example, another light source, an electron beam or any other energy or radiation source can be used which is suitable for solidifying the building material. Instead of deflecting a beam, exposure with a movable line exposer can also be used. Also on the selective mask sintering, in which an extended light source and a mask are used, or on the high-speed sintering (HSS), in which a material is selectively applied to the build material, which the Radiation absorption increased at the corresponding points (absorption sintering) or reduced (inhibition sintering) and then exposed non-selectively over a large area or with a movable line exposer, the invention can be applied.

Instead of introducing energy, the applied building material can also be selectively solidified by 3D printing, for example by applying an adhesive. In general, the invention relates to the additive manufacturing of an object by means of layer-wise application and selective solidification of a building material, regardless of the manner in which the building material is solidified.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included 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.

Patent literature cited

• WO 2015/144884 A1 [0004]

Claims (15)

Manufacturing device (1) for the additive manufacturing of a three-dimensional object (2), the object (2) being produced by applying a building material (13) layer on layer and selectively solidifying the building material, in particular by supplying radiation energy, at locations in each layer, which are assigned to the cross-section of the object (2) in this layer by scanning the locations with at least one exposure area, in particular a radiation exposure area of an energy beam (22), the manufacturing device (1) comprising: - a building container (5) for receiving the building material, - A process chamber (3) provided above the building container (5), - A construction field (10) provided between the construction container (5) and the process chamber (3), - a consolidation device (20) for the selective consolidation of the building material, - A flow device for generating a gas flow (30) in the manufacturing device (1), the flow device comprising a flow modification element (32, 40) for introducing the gas flow (30) into the process chamber (3), the flow modification element (32, 40) includes: - A body with a gas inlet side (41) and a gas outlet side (42) and - A plurality of channels (43) which penetrate the body from the gas inlet side (419 to the gas outlet side (42), and which have an inlet opening (48) on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42) and are separated from one another by a wall, a channel cross-sectional area (44) of at least one channel (43) perpendicular to an extension direction of the channel, preferably the channel cross-sectional areas (44) of a majority of the channels, particularly preferably the channel cross-sectional areas (44) of all channels, in a first length section (152) of the channel or channels starting from the outlet opening (49) along the extension direction, the first length section (152) being shorter than a total length (L) of the channel or channels between the inlet opening (48) and the outlet opening (49). Manufacturing device after Claim 1 , wherein at least one channel (43), preferably a majority of the channels (43), more preferably all channels (43) of the flow modification element (40) comprises a second length section (153), the channel cross-sectional area (s) (44) of the Channel or channels in the second length section (153) is / are substantially constant, and preferably the second length section (153) adjoins the first length section (152) along the direction of extension. Manufacturing device according to Claim 1 or 2nd , wherein at least one channel (43), preferably a majority of the channels (43), more preferably all channels (43) of the flow modification element (40) comprises a third length section (151) which connects to the inlet opening (48) of the flow modification element ( 40), the channel cross-sectional area (s) (44) of the channel or channels in the third length section (151) starting from the inlet opening (48) decreasing / decreasing along the direction of extension. Manufacturing device according to one of the Claims 1 to 3rd , wherein the channel cross-sectional area (s) (44) in the first length section (152) decreases / decreases according to a monotonous, preferably strictly monotonous, falling function and / or according to a smooth function, the channel cross-sectional area (s) (44) in the first Length section (152) particularly preferably reduced / reduced according to a linear function. Manufacturing device according to one of the Claims 1 to 4th , wherein the channel cross-sectional area (s) (44) in the first length section (152) decreases / decrease along a single direction transverse, preferably perpendicular, to the direction of extension, or wherein the channel cross-sectional area (s) (44) in the first length section (152) along at least two mutually different directions transversely, preferably perpendicularly, reduced / reduced to the direction of extension. Manufacturing device according to one of the Claims 1 to 5 , wherein the direction of extension is straight and the inlet opening (48) and the outlet opening (49) of at least one channel (43), preferably a majority of the channels (43), more preferably all channels (43) of the flow modification element (40) are each arranged and / or are oriented such that the direction of extension extends through their respective center of area, the direction of extension of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element preferably running parallel to the construction field (10), the directions of extension of the majority of the Channels, more preferably all channels of the flow modification element run parallel to each other. Manufacturing device according to one of the Claims 1 to 6 , wherein the first length section (152) at least 30%, preferably at least 40%, more preferably at least 50% of the total length (L) of the at least one channel, preferably the majority of the channels, more preferably all channels of the flow modification element between the inlet opening (48) and the outlet opening (49) and / or wherein an angle of inclination (γ) of the wall of the channel or channels relative to the direction of extension of the channel or channels in the first length section (152) is at least 1 °, preferably at least 2 °, particularly preferably at least 3 ° and / or at most 20 °, preferably at most 10 °, particularly preferably at most 5 °. Manufacturing device according to one of the Claims 1 to 7 , wherein a minimum channel cross-sectional area of at least one channel (43), preferably a majority of the channels (43), particularly preferably all channels (43) at most 90%, preferably at most 60%, particularly preferably at most 30% of a maximum channel cross-sectional area of the channel (43) or the respective channels (43). Manufacturing device according to one of the Claims 1 to 8th , wherein the flow modification element (40) is arranged in a recess in a wall (4) of the process chamber (3) and a minimally surrounding rectangle around the outlet openings (49) preferably extends essentially upwards from a plane of the construction field (10) . Manufacturing device according to one of the Claims 1 to 9 , wherein the flow modification element (40) at least on a horizontally adjacent side of the channels (43) has at least one guide channel (51, 52), preferably a plurality of guide channels (51, 52) for generating a guide flow over a bottom of the process chamber (3) the construction field (10), the guide channel (51, 52) or the guide channels (51, 52) penetrating the body of the flow modification element (40) from the gas inlet side (41) to the gas outlet side (42) and an inlet opening (48) has / have on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42) and are separated from one another by a wall, preferably at least one guide channel (51, 52), preferably a majority of the guide channels (51, 52) , particularly preferably all guide channels (51, 52) comprise a first guide channel length section (53) which adjoins the gas inlet side (41) and whose guide channel cross-sectional area (44) extends starting from the inlet opening (48) along a direction of extension of the guide channel (51, 52), the guide channel (51, 52) or the guide channels (51, 52) preferably comprising a second guide channel length section (54), which connects to the gas outlet side (42) and whose guide channel cross-sectional area (44) is essentially constant, the guide channel (51, 52) or the guide channels (51, 52) being particularly preferably through the first guide channel length section (53) and the second Guide channel length section (54) are formed and / or wherein the channels (43) are preferably arranged in a three-dimensional matrix and the guide channel (51, 52) or the guide channels (51, 52) on a horizontally adjacent side of the three-dimensional matrix of Channels (43) is / are arranged. Method for additively producing a three-dimensional object (2) with the steps: Applying a building material (13) layer by layer, selective solidification of the building material, in particular by supplying radiation energy, at locations in each layer which are assigned to the cross section of the object (2) in this layer, by the locations by means of a consolidation device (20) with at least one exposure region, in particular a radiation exposure region of an energy beam (22), can be scanned, and Repeating the layer-by-layer application and selective solidification until the object (2) is finished, the building material is provided in a building container (5), a process chamber (3) is provided above the building container (5), and a building field (10) is provided between the building container (5) and the process chamber (3), wherein a gas flow (33) is generated in the production device (1) at least temporarily during the production of the three-dimensional object (2) by means of a flow device, the flow device being a flow modification element (32, 40) for introducing the gas flow (33) into the process chamber ( 3) includes wherein the flow modification element (40) comprises: - a body with a gas inlet side (41) and a gas outlet side (42) and - A plurality of channels (43) which penetrate the body from the gas inlet side (41) to the gas outlet side (42) and which have an inlet opening (48) on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42 ) and are separated from each other by a wall, a channel cross-sectional area (44) of at least one channel (43) perpendicular to an extension direction of the channel, preferably the channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, starting from a first length section (152) of the channel or channels the outlet opening (49) is reduced / reduced along the direction of extension, wherein the first length section (152) is shorter than a total length (L) of the channel (43) or channels (43) between the inlet opening (41) and the outlet opening (42). Flow modification element (40) for introducing a gas stream (33) into a process chamber (3) of a device (1) for additive manufacturing of a three-dimensional object (2), in particular into a process chamber (3) of a device (1) according to one of the Claims 1 to 10th , with - a body with a gas inlet side (41) and a gas outlet side (42) and - a plurality of channels (43) which penetrate the body from the gas inlet side (41) to the gas outlet side (42), and which have an inlet opening (48 ) on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42) and are separated from one another by a wall, a channel cross-sectional area (44) of at least one channel (43) being perpendicular to an extension direction of the channel, preferably that Channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, in a first length section (152) of the channel (43) or of the channels (43) starting from the outlet opening (49) along the extension direction, the first length section (152) shorter than a total length (L) of the channel (43) or channels (43) between the inlet opening (48) and the Exit opening (49) is. Flow device for a device (1) for the additive manufacturing of a three-dimensional object (2) by layer-wise solidification of building material (13) with a flow modification element (40) according to Claim 12 . Use of a flow modification element (32, 40) for introducing a gas flow (33) in a device (1) for additively producing a three-dimensional object (2), in particular in a device (1) according to one of the Claims 1 to 10th , wherein the flow modification element (40) comprises: - a body with a gas inlet side (41) and a gas outlet side (42) and - a plurality of channels (43) which penetrate the body from the gas inlet side (41) to the gas outlet side (42) , and which have an inlet opening (48) on the gas inlet side (41) and an outlet opening (49) on the gas outlet side (42) and are separated from one another by a wall, a channel cross-sectional area (44) of at least one channel (43) being perpendicular to a direction of extension of the channel (43), preferably the channel cross-sectional areas of a majority of the channels, particularly preferably the channel cross-sectional areas of all channels, in a first length section (152) of the channel or channels starting from the outlet opening (49) along the direction of extension, wherein the first length section (152) is shorter than a total length (L) of the channel (43) or the channels (43 ) between the inlet opening (48) and the outlet opening (49). Flowing process for generating a gas flow (33) in a process chamber (3) of a manufacturing device (1) for the additive manufacturing of a three-dimensional object (2), in particular a manufacturing device (1) according to one of the Claims 1 to 10th , wherein the flow method comprises at least one step of generating a gas stream (33) by means of a gas supply device, and a step of introducing the gas stream (33) into the process chamber (3) by a flow modification element (40) according to Claim 12 .

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