DE102020128028A1 - Device for the additive manufacturing of components, in particular by means of selective melting or sintering - Google Patents

Abstract

The invention relates to a device for the generative manufacturing of components, in particular by means of selective melting or sintering, with a light source for generating a light beam, a processing head, which is either coupled to the light source with a beam guide so that the light beam is guided to the processing head, or the light source is arranged directly on the processing head so that a light beam can be directed from the processing head to a processing area, the processing head being movably mounted so that the light beam can be directed to any point in the processing area. The invention is characterized in that a plurality of processing heads are provided for respectively directing a bundle of light beams on the processing area, and the processing heads are each arranged on a carriage which can be moved along a traverse. This allows powder to be melted or sintered at several points at the same time. The processing heads are preferably arranged on swivel arms. This allows a very simple and inexpensive configuration of the device.

Description

The present invention relates to a device for the additive manufacturing of components, in particular by means of selective melting or sintering.

From the DE 10 2016 222 068 A1 a device and a method for generative component production with several spatially separated steel guides emerge. A processing head has a number of optical switching elements, via which a number of beams can be directed to the target position. The processing head is slidably aligned on a linear axis. The linear axis is, in turn, slidably mounted on a linear axis that is perpendicular to it. This enables an XY movement. The laser beam source or sources are mounted on the linear axis.

the WO 2018/202643 A1 discloses an apparatus for additive manufacturing by selective laser sintering. One or more lasers are associated with one or more laser heads. These lasers are distributed to the individual heads via the beam splitter. The heads can be moved on rails in the X and Y directions. The heads can be moved independently of each other. The light is supplied to the heads by mirrors.

From the US 10,399,183 B2 is an additive manufacturing process in which an optical head is supplied with a laser beam via a glass fiber. This allows multiple laser beams to be directed to the same head and exited in parallel. This allows parallel melting points on the surface of the powder bed.

A similar procedure is in US 10,399,145 B2 described.

In the U.S. 2015/0283612 A1 , the US 2014/0198365 A1 and the JP2009-65 09A discloses selective laser sintering apparatus having multiple optical heads capable of directing laser beams onto a bed of powder. These heads cannot be moved in the X and Y directions themselves, but direct the laser beam to the appropriate positions via mirrors. The advantage here is that the location of the laser focal point can be changed quickly. In this case, however, the heads must be comparatively far away from the powder bed and can only illuminate a limited area.

the DE 10 053 742 C5 , the US 9,011,136 B1 and the CN 206065685 U show devices for sintering with a cross slide arrangement, an additive manufacturing process with multiple heads for plastic printing and a device with a head that has both a 3D print and a 3D cutting element.

The invention is based on the object of creating a device for the additive manufacturing of components, in particular by means of selective melting or sintering, which is of simple design, allows a high production speed and with which 3D components can be manufactured with high precision.

The object is achieved by a device having the features of claim 1, by a device having the features of claim 14, by a device having the features of claim 19 and by a device having the features of claim 25. Advantageous configurations are specified in the dependent claims.

A device according to the invention for the additive manufacturing of components, in particular by means of selective melting or sintering, comprises a light source for generating a light beam, a processing head, which is either coupled to the light source with a beam guide so that the light beam is guided to the processing head, or the light source is arranged directly on the processing head so that a light beam can be directed from the processing head to a processing area, the processing head being movably mounted so that the light beam can be directed to different points in the processing area.

The device is characterized in that a plurality of processing heads are provided for respectively directing a bundle of light beams onto the processing area, and the processing heads are each arranged on a carriage which can be moved along a traverse.

By providing several processing heads, several bundles of light beams can be directed onto the processing area at the same time, so that several points in the processing area can be melted or sintered in parallel. The processing heads are arranged on or on a carriage and can be moved along a traverse. This allows easy and reliable positioning of the processing heads over the processing area.

The machining heads are preferably each arranged on one of the carriages by means of a pivotable swivel arm. By providing such swivel arms for the machining heads, the machining heads can quickly cover a large section of the machining area ches can be positioned anywhere. This section extends around the traverse, along which the respective carriage with the respective machining head can be moved in an area around the pivot axis of the pivot arm, which extends on both sides by a width that corresponds to the length of the pivot arm. This section is thus in the form of a strip around the traverses with a width which corresponds to approximately twice the length of the swivel arms. This strip-shaped section is referred to below as the coverage area, since the processing heads, which are arranged on the carriage of a traverse, can be arranged at any position within the coverage area and thus apply a light beam bundle or cover the processing area at any point in the coverage area be able.

It can be expedient to position the processing heads only in a limited angular range of the swivel arms, because the more the swivel arms swivel the processing head away from the traverse, the more imprecise the position of the processing head becomes in the direction parallel to the traverse. The angular range can be limited, for example, to a maximum pivoting angle with respect to the traverse of a maximum of 60° or a maximum of 45°. With a maximum swivel angle of 45°, the width of the coverage area is reduced to the length of the swivel arm.

The device can have several traverses which are arranged parallel to one another. The trusses are preferably spaced such that the coverage areas overlap from adjacent trusses.

The beam guidance for the respective bundle of light beams can be formed along the swivel arms by means of reflector elements. This allows for very light swivel arms that have a low rotational moment of inertia so that they can be quickly swiveled to any rotational position.

The swivel arms are preferably made of plastic, in particular made of fiber-reinforced plastic. A mirror can be provided at each end remote from the pivot axis of the pivot arm for directing the respective light beam onto the processing area.

The beam guides can be designed at least partially as light guides. The light guide can extend from the light source to the respective processing head. However, the respective light guide can also only be guided from the light source to the pivoted end of the respective swivel arm and its end arranged there in such a way that the light beam couples into a beam guide along the swivel arm, which is formed by means of reflector elements. Such an embodiment has the advantage that the pivoting arm can be rotated through 360° or more without the light guide having to be rotated. The end of the light guide, at which the light from the light guide is coupled into the beam guide on the swivel arm, can be arranged stationary with respect to the carriage on which the swivel arm is attached.

The end of the light guide can alternatively be arranged stationary on the swivel arm in such a way that the bundle of light rays is emitted in the direction of the free end of the swivel arm, preferably parallel to the swivel arm. At the free end of the swivel arm, a reflector element can be provided for directing the respective bundle of light beams onto the processing area, such as a deflection mirror, for example.

The reflector element can be a parabolic mirror or a mirror with a free-form surface for focusing the light, so that no optical lens is required in the beam path.

The traverses on which the carriages are movably mounted can be stationary. This is particularly advantageous in connection with an embodiment with processing heads arranged on swivel arms, since such a stationary arrangement can be controlled much more easily to avoid collisions between different swivel arms than with a device in which the swivel arms can be swiveled, the carriages can be moved along the traverses and the Traverses themselves are movable transversely to their longitudinal direction. In addition, with a stationary arrangement of the traverses and swivel arms on the carriages, complete coverage of the processing area can be achieved with a few traverses, provided the swivel arms are not too short. Since the processing heads arranged at the free ends of the swivel arms can be designed very lightly, for example only with a small mirror, even with longer swivel arms with a length of, for example, at least 10 cm, preferably at least 15 cm, and in particular at least 20 cm, a small Rotational moment of inertia can be achieved.

The device can be designed in such a way that one or more traverses can be retrofitted. As a result, on the one hand, the processing area can be subsequently enlarged and, on the other hand, the density of traverses and thus of processing heads can be increased in a predetermined processing area. With an increase Due to the density of the traverses and thus a reduction in the distance between the traverses, it can be expedient to fasten the swivel arms to the carriage in an interchangeable manner, so that correspondingly shorter swivel arms can be used if the distance between the traverses is shorter.

Preferably, at least two carriages that can be moved independently of one another are mounted on each traverse, with each carriage having a processing head. More than two carriages, for example three or four carriages, can also be provided per traverse.

A plurality of light sources are preferably provided, each of which is assigned to one or more processing heads. The light sources are preferably lasers, in particular CO2 lasers or ND:YAG lasers. COz lasers are mainly used for melting or sintering of plastic powder ND:YAG lasers for melting or sintering of metal powder. Such a COz laser has, for example, a light output of 30 W to 70 W and an ND:YAG laser of 100 W to 1,000 W and more. The light sources can also be light-emitting diodes, in particular super-luminescent light-emitting diodes, and/or semiconductor lasers.

By providing several light sources and several processing heads, which can be positioned independently of one another in the processing area, it is possible for powder to be melted or sintered at several points in the processing area at the same time in order to produce a 3D component. This simultaneous melting or sintering of the powder increases the production speed of the generative production with the present device compared to conventional devices. Even if the processing heads remain at the individual points a little longer, a high production speed can be achieved. This makes it possible for light sources with a comparatively low light output to be used. This significantly reduces the cost of the device.

A multiplexer can be provided for distributing the bundle of light rays from one of the light sources to different beam paths. Such a multiplexer is preferably useful in the case of very intense light sources with which the powder can be melted or sintered with short pulses. The device preferably has a powder bed in the processing area, in which powder can be located, which is selectively melted by means of the light beam bundle.

The powder can be metal powder or plastic powder.

The individual swivel arms can be arranged at different heights in order to avoid collisions when moving the swivel arms.

The individual light sources can be designed in such a way that they emit light beams with different frequencies or different frequency ranges and/or different intensities. This allows the selective melting or sintering process to be controlled individually. This allows, for example, control of the porosity of the product manufactured with it.

The bundles of light beams can also be focused to different degrees on the processing area. The focus can be set, for example, by means of a lens and/or a height adjustment of the processing heads.

With the device according to the invention, powder in a powder bed can be melted or sintered at several points at the same time.

An inert gas atmosphere, in particular a nitrogen and/or argon atmosphere, can be formed in the entire device. By using an inert gas atmosphere, oxidation of the powder or the component can be prevented during component manufacture. When forming and maintaining the inert gas atmosphere, it is possible to easily filter dirt particles out of the interior of the device.

According to a further aspect of the invention, a device for the additive manufacturing of components, in particular by means of selective melting or sintering, is provided, with a processing table with a preferably horizontal table top, which forms a support surface for the powder bed, the processing table having a table top at least partially laterally delimiting wall has, and wherein the table top and the wall together define the processing area. The device is characterized in that the wall can be moved preferably perpendicularly to the tabletop.

When manufacturing a component, the wall is moved vertically relative to the processing table after one or more component layers have been produced. For this purpose, the upper side of the wall can form a flat surface with the table top of the processing table at the beginning of the component production. Powder is applied to the table top and smoothed out. A layer of powder can be about 20 µm - 100 µm thick. The first component layer is then created by connecting at least some of the powder particles. The connection can be made by melting zen and cooling, by sintering or by local application of a binder. After the production of the first component layer, the wall can be moved upwards by the height of the first component layer. In this way, a chamber is formed between the wall and the bearing surface. The powder bed is formed in this chamber. The powder bed comprises the component layer that has already been formed and the remaining powder that is not connected to one another. Another layer of powder can then be applied, smoothed out and a second component layer can be produced. The height of the wall can then be adjusted again by the layer thickness of the second component layer. The chamber formed by the wall and the bearing surface is enlarged in the vertical direction in this way and then includes the two component layers and the remaining powder material that is not connected to one another. The aforementioned steps are repeated until the component is completely manufactured. The wall, which is generally designed to be lighter than the processing table, can be moved with little effort. The wall can be moved after one or more layers have been formed.

It is advantageous if the processing table is designed to be stationary and cannot be moved. The known structure, namely that the processing table is moved downwards relative to the fixed wall surrounding the processing table during the production of the component, can thus be reversed. A device for the additive manufacturing of components with a base area of the processing table of 1.5 mx 1 m and a stroke of 0.5 m results in a working volume of 0.75 m ³ . If this working volume is filled with aluminum powder, the content weighs around 2 t. In the case of steel powder, the weight is around 6 t. Since only the wall, which is usually significantly lighter than the processing table and the additively manufactured object located on it, has to be moved, a small and inexpensive drive can be used. At the same time, the structure of the processing table can be designed to be particularly cost-effective but still stable, since the processing table does not need to be able to be moved. This further reduces the overall cost of the device.

For example, an electric, pneumatic and/or hydraulic drive can be used to adjust the wall vertically.

The wall can be provided at its upper edge with a collar which projects horizontally outwards and which prevents powder from falling onto a foundation in areas which are not intended for this. The collar can only be provided on one side of the powder bed or can be formed on several or even circumferentially.

The wall can be formed from several wall sections, the wall sections being movable individually and/or together. Individual wall sections can then be moved independently of one another. The wall can thus be adjusted to a large number of possible applications.

An application dispenser for applying powder to be selectively melted or sintered to the processing table or to the processing area can be provided. The order dispenser can be moved horizontally over the processing table in order to be able to distribute the powder over the entire processing area. The application dispenser can have a squeegee or be coupled to a squeegee so that the applied powder is smoothed out. The installation space or the base area of the device can be reduced by using an order dispenser, since a storage cylinder can be dispensed with. However, the use of a storage cylinder instead of an order dispenser can be advantageous in order to reduce the turbulence of the atmosphere inside the device caused by movement of the order dispenser.

The wall can be moved together with at least one other component, preferably a light source and/or a processing head and/or a squeegee and/or an application dispenser for applying powder material and/or a storage cylinder. It is particularly advantageous if the height of the processing heads can be adjusted together with the wall. In this way it can be ensured that the processing heads are always at the same distance from the processing area or from the surface of the powder bed. A complex setting of an optimal distance between the processing head and the processing area can thus be dispensed with, as can refocusing or adjusting the optics of the processing head. The person skilled in the art knows which components, depending on the structure of the device, should preferably have a constant distance from the wall or from the processing area or from one another during component manufacture. These components can be designed to be movable coupled to the wall. Only a single drive is then required to move these components relative to the machining table, as a result of which the design is simple.

The wall can vary depending on the thickness of the next component layer to be formed will drive. It is possible that the individual component layers have different thicknesses. During production, individual component layers can be made thicker than others if high molding accuracy is not important in the corresponding component areas. If, on the other hand, a high degree of dimensional accuracy is required in individual component areas, the component layer to be manufactured can have a smaller thickness. In this way, component production can be accelerated in individual component areas and thus overall. The component can thus be manufactured particularly quickly, depending on the dimensional accuracy required in the respective areas.

In a preferred embodiment, a collecting device is provided, preferably in the form of a collecting basin, for collecting excess powder which comes out of the processing area. During production, powder can get out of the processing area, for example powder can be pushed through the squeegee from the processing table or from the table top or from the collar. This excess powder can be picked up by the collection device. In a particularly simple embodiment, the collecting device can be formed by a collecting or collection basin into which the excess powder falls. This excess powder can then be collected and reused. The collection basin may be positioned partially or completely around the worktable, wall and/or collar so that excess powder brushed off the worktable, wall and/or collar can fall into the collection basin.

A suction and filter can be provided to suck off, filter and reuse the excess powder. The powder picked up by the collecting device is sucked off, then fed to a filter and conveyed back to the processing area in a circuit. The filter can filter out powder grains and/or dirt particles that are too large and/or already connected to one another. A filter can have a filter size of 120 μm, for example, so that only particles with a particle size of less than 120 μm can pass through the filter. Different filter sizes can be used depending on the powder and powder grain sizes used. The powder material cleaned in this way can be fed to a storage container and/or the order dispenser for reuse. This recirculation of the powder material allows the loss of material to be kept low. At the same time, it can be ensured that no powder grains that are already connected to one another are reused or dirt particles are used. The use of powder grains or dirt particles that are already connected to each other can lead to inaccuracies or defects in the 3D component and negatively affect stability or strength. The accuracy and quality of the component production can still be ensured to a high degree by using an extraction system and a filter.

The work table can be tempered and maintained at a predetermined temperature. In this way, stresses in the component, especially in the first layers, can be avoided. When producing a metal component, the work table can be heated, for example, to a temperature between 100°C and 300°C, preferably to a temperature between 150°C and 200°C. During the additive manufacturing of a plastic component, the temperature of the worktable can be lower and can be between 40°C and 120°C, for example, preferably between 60°C and 100°C. The temperature can be adjusted to the material used.

Optics, in particular zoom optics, are preferably provided in order to change the focusing of the emitted light beam. The focussing of the light beam can be easily adjusted to different distances from the processing area. At the same time, the energy input and the irradiated area can be changed by a targeted focus setting.

According to a further aspect of the invention, a device for the additive manufacturing of components, in particular by means of selective melting or sintering, is provided with at least one movable component, preferably a processing head and/or a processing table and/or a wall and/or a squeegee and/or an order dispenser, and a drive for moving the movable component. The device is characterized in that at least one distance sensor is provided for preferably electro-optical distance measurement. The distance sensor can be arranged on or on the movable component and can measure the distance to another object or the distance between the sensor and the other object. However, it is also possible for the distance sensor to be arranged on another object and to measure the distance from the movable component. In this way, the distance between the moving component and another object can be measured and determined at any time.

The distance sensor is preferably arranged in a stationary manner in order to measure the distance between the sensor and the movable component. This way the distance between a fix point and the moving component can be measured and determined at any time. The movable component can have a reference object, with the distance sensor detecting the reference object and measuring the distance from the reference object. For example, a reflector, in particular a prism reflector, can be used as a reference object. The distance sensor can be pivotable in order to be able to be aligned with the reference object.

The distance can be measured by means of triangulation and/or measurement of the phase position and/or measurement of the propagation time. A laser beam is emitted when measuring the distance by measuring the phase position. The phase shift of the reflected laser beam or its modulation in relation to the emitted beam depends on the distance. This phase shift can be measured and used to determine the distance traveled. The distance measurement by measuring the phase position has a high level of accuracy. With laser triangulation, a light beam is focused on the measurement object and observed with a camera located next to the sensor, a spatially resolving photodiode or a CCD line. If the distance between the measurement object and the sensor changes, the angle at which the point of light is observed also changes, and with it the position of its image on the photo receiver. The distance of the object from the laser projector is calculated from the change in position with the help of angle functions. Distance measurement using triangulation is simple, inexpensive and yet very precise. When measuring the transit time, a light pulse or a modulated light beam is emitted. Travel time is the time it takes for the light beam to travel from the source to a reflector, usually a retroreflector, and back to the source. By measuring this transit time, the distance between the source and the object can be determined using the speed of light. As an alternative or in addition, sensors can also be used to measure distances, which can scan lines or areas or planes, or can carry out spatial measurements, such as stereo cameras for three-dimensional localization of one or more objects. Corresponding sensors do not have to be pivotable due to their large recording area.

Instead of optical sensors, other sensors, such as ultrasonic sensors or sensors that determine the distance using the propagation time of radio waves, can also be used.

In an advantageous embodiment, a control and regulation device is provided which is designed in such a way that the movable component can be moved into a target position depending on the measured distance between the distance sensor and the movable component. The use of distance sensors together with a control and regulation enables the use of an inexpensive and particularly light moving device for moving the moving component. A low-cost and lightweight movement device has low positioning accuracy, but can be moved particularly quickly. The position of the moveable component can be regulated depending on the distance of the moveable component from the distance sensor. The more the moving component approaches its target position, the slower the component can be moved. In this way it can be ensured that the movable component can reach the target position exactly. The movement device can be designed in a simple and, above all, light and inexpensive manner, since the precision of the movement and positioning is ensured by the distance measurement and the regulation in a closed control loop. Proportional controllers, so-called P controllers, proportional-integral controllers, so-called PI controllers, and/or proportional-integral-derivative controllers, so-called PID controllers, can be used as controllers in the control loop.

Two, preferably three, distance sensors can be provided for distance measurement between the distance sensors and the movable component in order to determine the spatial position of the movable component. If the movable component is only moved in one plane, i.e. in two dimensions, its position can be determined exactly by measuring the distance using two distance sensors. By measuring three distances between the movable component and three stationary distance sensors, the spatial position of the movable component can be precisely determined in three dimensions. If the movable component is only moved in one direction, one sensor for distance measurement can also be sufficient.

In a preferred embodiment, more than three distance sensors and at least two moving components are provided, with each moving component being able to be detected in any position by at least three distance sensors for distance measurement. A distance sensor can be used to measure the distance between itself and the two moving components. Depending on the positions of a first movable component, a distance sensor can be covered by this first movable component in such a way that a distance measurement to a second movable component is not possible. In such a case, the distance can be measured using another distance sensor that has direct optical access to the second movable component. This makes it possible to use different or the same distance sensors for each position determination of a movable component by distance measurement.

The distance sensors can be arranged in a stationary manner in the device, for example connected to the foundation of the device via a carrier. The distance sensors can determine the position of the surface of the powder bed via a distance measurement and then determine the position of a movable component, for example a processing head, with the aid of a further distance measurement. Depending on the position of the powder bed, ie the height of the powder bed, the processing head can be moved into a target position in order to set the required distance between the processing head and the surface of the powder bed. One or more machining heads can be moved into their desired position with the aid of the control and regulation device described above. It is also possible that one or more distance sensors are connected to a processing head or arranged on it and the distance between the processing head and the powder bed surface is determined in order to then move the processing heads to a target distance from the surface of the powder bed.

In addition, it is also possible for the position of one or more processing heads to be adjusted as a function of the position of the movable wall, in particular an upper edge and/or a horizontal surface. To determine the distance between the moveable wall and the processing head, one or more distance sensors can be connected to the processing head and/or arranged in a stationary manner in the device.

Instead of the position of one or more processing heads, the position of a traverse or another component of a movement direction, for example a carriage, can be determined and positioned relative to the movable wall or the surface of the powder bed. For this purpose, one or more distance sensors can be connected directly to the traverse and measure the distance to the surface of the powder bed.

In the same way, a squeegee can also be positioned relative to the powder bed surface or a movable wall. For this purpose, at least one distance sensor can be connected to the squeegee or arranged in a stationary manner in the device.

It can also be possible to position an order dispenser depending on the position of the movable wall or the powder bed surface. For this purpose, the order dispenser can have at least one distance sensor or at least one distance sensor can be stationarily arranged in the device.

The movable wall can also be moved relative to the surface of the powder bed, for example to a position that is one layer thicker than the powder bed. To this end, it is advantageous if the distance sensors are arranged in a stationary manner in the device.

In addition, it is also possible to move a storage cylinder relative to a processing table. With a device of the aforementioned type, the processing table can also be moved in a controlled manner. For example, after the completion of a component layer, the processing table can be lowered by a defined layer thickness in order to be able to apply a new layer of powder. In this way, the distance between the processing heads and the surface of the powder layer can be kept constant for each component layer to be created. The distance sensors are then preferably arranged in a stationary manner in the device.

Several components can also be moved coupled together. For example, a squeegee together with one or more processing heads and/or together with an order dispenser can be positioned in a controlled manner at a distance from the surface of the powder bed that is required in each case in the vertical direction. The vertical distance between the squeegee and the processing heads and/or the order dispenser is then the same at all times.

Each movable component can be permanently assigned three distance sensors for distance measurement. The same three distance sensors can be associated with the same moving component for each distance measurement. However, it is also possible for the distance sensors to be reassigned to a component for each distance measurement. In this way, for each new distance measurement, each movable component can be assigned partially or completely different distance sensors than for a previous distance measurement.

According to a further aspect of the invention is a device for the additive manufacturing of Components, in particular by means of selective melting or sintering, provided with a glass plate, the surface of which forms a contact surface for powder, a processing area above the glass plate, a light source for generating a light beam, a processing head arranged below the glass plate, which is either connected with a beam guide to the light source is coupled so that the light beam is guided to the processing head, or the light source is arranged directly on the processing head so that a light beam can be directed from the processing head through the glass plate onto the processing area, with the processing head being movably mounted so that the light beam is on different places in the processing area can be steered. The device is characterized in that a plurality of processing heads are provided for guiding a light beam through the glass plate onto the processing area, with the processing heads each being arranged on a carriage which can be moved along a traverse. In the device mentioned above, powder can be deposited on the surface of the glass plate, for example with the aid of an application dispenser. The glass plate forms a support surface for the powder. A squeegee can be provided to smooth out the layer of powder. A supporting body can then be placed on the powder layer. A light beam can be directed through the glass plate onto the corresponding areas with powder from a processing head which is arranged below the glass plate. The powder can be selectively melted or sintered and bonded together, thereby forming a first component layer on the support body. The component layer formed can then be raised together with the supporting body. For this purpose, a lifting device can be provided for supporting gripping and lifting of the component or the component layers in the vertical direction. The powder still on the glass plate can be removed from it. Powder can then be applied again to the glass plate. The already formed component layer can be placed on the applied powder. By directing a light beam onto the processing area again, the new component layer can be formed and connected to the first component layer. These steps can be repeated any number of times until the component is fully formed. The component will be manufactured from top to bottom. With this structure of the device, material can be saved since the powder can only be deposited in the areas where a component layer is to be formed. It is then not necessary to cover the entire glass plate with powder. The glass plate has to carry significantly less weight, since the component is held by the lifting device and the glass plate thus only carries the powder bed for the new component layer to be formed. The component layers that have already been formed are freely accessible and are not surrounded by powder. Therefore, the component can already be further processed during production, for example by machining the component.

The embodiments of the invention described above can be combined with one another as required. The aspects of the invention described above are not limited to the combinations of inventive features specified by the selected paragraph formatting.

Further features of the present invention result from the following description of the invention based on the drawings and the drawings themselves. All features described and/or illustrated form the subject matter of the present invention, either alone or in any combination, regardless of their summary in the claims or their reciprocal relationships.

• 1 eine Prozesskammer einer Vorrichtung zum generativen Fertigen von Bauteilen in einer seitlichen Schnittansicht,
• 2 einen Vorratszylinder und ein Pulverbett in der Draufsicht mit mehreren Bearbeitungsköpfen, welche über dem Pulverbett frei anordbar sind, in einer Draufsicht,
• 3a einen Schwenkarm zur Positionierung eines Bearbeitungskopfes, wobei eine Strahlführung aus einem Lichtleiter ausgebildet ist, der sich von einer Lichtquelle zum Bearbeitungskopf erstreckt,
• 3b einen weiteren Schwenkarm, der an seinem freien Ende eine Lichtquelle aufweist in der Seitenansicht,
• 3c einen weiteren Schwenkarm, bei dem eine Strahlführung als Lichtleiter ausgebildet ist, welche sich von der Lichtquelle bis zu dem Schwenkgelenk des Schwenkarms erstreckt, wobei entlang dem Schwenkarm eine mittels Reflektorelemente ausgebildete Strahlführung vorgesehen ist, in einer schematischen, seitlichen Schnittansicht,
• 3d einen weiteren Schwenkarm mit einem gepumpten Laser, wobei Lichtpumpe und Resonator räumlich getrennt angeordnet sind in einer Seitenansicht,
• 3e einen weiteren Schwenkarm, bei dem eine Strahlführung als Lichtleiter ausgebildet ist, welche sich von der Lichtquelle bis zu Schwenkarm erstreckt und sein der Lichtquelle entferntes Ende parallel zum Schwenkarm angeordnet ist und zum freien Ende des Schwenkarms 18 zeigt, wobei am freien Ende des Schwenkarms ein Reflektorelement zum Umlenken des Lichtstrahlbündels vorgesehen ist, in einer schematischen, seitlichen Schnittansicht,
• 4 eine zweite Ausführungsform einer Prozesskammer einer Vorrichtung zum generativen Fertigen von Bauteilen in einer seitlichen Schnittansicht,
• 5 einen Schwenkarm zur Positionierung eines Bearbeitungskopfes mit Sensoren zur Erfassung der räumlichen Position des Bearbeitungskopfes in einer Seitenansicht,
• 6 einen Ablauf zur Einstellung der räumlichen Position des in 5 gezeigten Bearbeitungskopfes und
• 7 einen Bearbeitungstisch mit einer Glasplatte und mehreren Bearbeitungsköpfen, die unterhalb der Glasplatte frei anordbar sind, in einer seitlichen Schnittansicht.

The invention is explained in more detail below by way of example with reference to the drawings. The drawings show schematically in:

• 1 a process chamber of a device for the additive manufacturing of components in a side sectional view,
• 2 a storage cylinder and a powder bed in a top view with several processing heads, which can be freely arranged above the powder bed, in a top view,
• 3a a swivel arm for positioning a processing head, wherein a beam guide is formed from a light guide that extends from a light source to the processing head,
• 3b another swivel arm, which has a light source at its free end in the side view,
• 3c a further swivel arm, in which a beam guide is designed as a light guide, which extends from the light source to the swivel joint of the swivel arm, wherein a beam guide designed by means of reflector elements is provided along the swivel arm, in a schematic, lateral sectional view,
• 3d another swivel arm with a pumped laser, with the light pump and resonator being arranged spatially separately in a side view,
• 3e another swivel arm, in which a beam guide is designed as a light guide which extends from the light source to the swivel arm and its end remote from the light source is arranged parallel to the swivel arm and points to the free end of the swivel arm 18, a reflector element for deflecting the light beam being provided at the free end of the swivel arm, in a schematic, side sectional view,
• 4 a second embodiment of a process chamber of a device for the additive manufacturing of components in a side sectional view,
• 5 a swivel arm for positioning a processing head with sensors for detecting the spatial position of the processing head in a side view,
• 6 a procedure for adjusting the spatial position of the in 5 processing head shown and
• 7 a side sectional view of a processing table with a glass plate and several processing heads that can be freely arranged below the glass plate.

An exemplary embodiment of a device for the additive manufacturing of components, which is briefly referred to as “3D printer” 1 in the present case, is explained below. Such a 3D printer 1 has a process chamber 2 that is closed on all sides, in which there is a powder bed 3 and a storage cylinder 4 ( 1 , 2 ). A storage piston 5 is arranged in the storage cylinder 4 and can be raised or lowered vertically by means of a first lifting piston/cylinder unit 6 . The powder bed 3 is likewise formed from a cylindrical body which is approximately rectangular when viewed from above, in which a production piston 7 is mounted so that it can move vertically and which can be actuated by means of a second reciprocating piston/cylinder unit 8 . The powder bed forms a processing area in which a 3D component 31 can be produced.

The storage cylinder 4 and the powder bed 3 are located in the process chamber 2 . The powder bed 3 is arranged adjacent to the storage cylinder 4 . A squeegee 9 is provided, which in the direction of movement 10 ( 1 ) can be moved in such a way that a powder 11 stored in the storage cylinder 4 can be spread into the powder bed 3 . A superficial powder layer of the storage cylinder 4 is thus transferred to the surface in the powder bed 3 with the squeegee 9 . By gradually raising the storage piston 5 and gradually lowering the production piston 7, the surface of the powder 11 in the powder bed 3 and in the storage cylinder 4 can be kept at approximately the same level.

In the area above the powder bed 3 there is a moving device 12 for moving a large number of processing heads 13 .

The moving device 12 comprises a plurality of cross members 14 which extend across the powder bed 3 . The traverses 14 are arranged parallel to one another. In the present embodiment, three traverses 14 are provided ( 1 , 2 ). The middle traverse 14 is arranged somewhat higher than the two outer traverses 14 .

The traverses 14 have an approximately rectangular cross-section, each with a rail profile 16 projecting on the vertical longitudinal side surfaces 15, which extend over the entire length of the traverse 14 ( 3a-3e ). On the rail profiles 16 of each traverse 14, two carriages 17 are displaceably mounted in the longitudinal direction of the traverses 14. The carriages 17 can be moved automatically along the respective traverse 14 by means of a drive device. The drive device can comprise a drive belt driven by an external motor, which is coupled to the respective carriage 17 . However, a drive mechanism such as a drive wheel driven by a motor can also be provided in the carriage 17 itself. In principle, it is also possible to drive the carriage by means of a linear motor, in which case the corresponding drive means and counter-drive means are to be provided on the carriage 17 and on the traverse 14 .

A swivel arm 18 is arranged on the carriage 17 by means of a swivel joint 19 . The swivel arm 18 is rotatably mounted with the swivel joint 19 about a vertical swivel axis 20 . A stepper motor (not shown) is provided on the carriage 17 for rotating the swivel arm 18 about the swivel axis 20 . The machining head 13 is provided at the end of the pivot arm 18 remote from the pivot axis 20 3a shown embodiment is formed by an end 22 of a light guide 21 and an optical lens 23 arranged at the end 22 of the light guide 21 . The processing head 13 is arranged in such a way that a light beam bundle 24 guided in the light guide is emitted vertically downwards.

The light guide is formed from a flexible optical fiber. The optical fiber can be, for example, a glass fiber or a polymer optical fiber.

The stepper motor and pivot joint 19 are located very close to the pivot axis. As a result, the essential mass of the parts that can be rotated with the pivot arm 18 is concentrated around the pivot axis 20 . The swivel arm 18 itself is comparatively light, so that the rotational moment of inertia is low and the swivel arm 18 can be rotated about the swivel axis 20 quickly and precisely.

The light guide 21 leads to a light source 25 which is arranged at a distance from the swivel arm 18 . The light source 25 is preferably a laser, in particular a CO ₂ laser or an ND:YAG laser or a fiber laser. The light source 25 can also be a semiconductor laser or a light-emitting diode, in particular a super-luminescent light-emitting diode.

An array of light sources 25 can also be provided, which has a light source 25 for each processing head 13 .

Further embodiments of the swivel arm are explained below, which are just like those above with reference to FIG 3a embodiment described are formed, unless otherwise specified.

In an alternative embodiment of the swivel arm 18 ( 3b ) the light source 25 together with the optical lens 23 is arranged directly at the end of the swivel arm 18 remote from the swivel axis 20 in such a way that a light beam 24 can be emitted vertically downwards. Otherwise, the swivel arm 18 is designed in exactly the same way as in the embodiment according to FIG 3a .

According to another embodiment ( 3c ) is a beam guide from the light source 25 to the carriage 17 by means of a light guide 26 and along the swivel arm 18 by means of reflector elements 27, 28 is formed. In the present exemplary embodiment, the reflector elements 27, 28 are each designed as mirrors. However, they can also be represented by other optical elements that deflect a light beam, such as prisms or the like.

The swivel arm 18 is designed as a hollow plastic tube, which can consist in particular of a fiber-reinforced plastic. Such a plastic tube is very light and stiff.

The swivel joint 19 has a vertically extending through-opening or through-hole 29 . The end of the light guide 26 remote from the light source 25 is arranged adjacent above the through hole 29 together with a coupling lens 30, so that the light beam generated by the light source 25 is transmitted via the light guide 26 and from there is coupled into the through hole 29 of the swivel joint 19. A first reflector element 27 is arranged below the through-hole 29 and deflects the light beam 24 in such a way that the light beam 24 is directed towards the free end of the swivel arm 18 . The second reflector element 28 is arranged at the free end of the swivel arm 18 remote from the swivel axis 20 and deflects the light beam 24 vertically downwards. Optionally, an optical lens 30 can be provided in the beam path between the end of the light guide 26, which is arranged adjacent to the swivel joint 19, and the second reflector element 28 for bundling the light beam bundle. Instead of the optical lens 30, a lens can also be provided, with which the degree of bundling of the light beam can be changed.

The first and/or second reflector element 27, 28 can be shaped in such a way, for example as a parabolic mirror or free-form mirror, that it bundles the reflected light. As a result, it is not necessary to arrange an optical lens in the beam path, or an optical lens with a low refractive power can be provided in the beam path.

When the processing head 13 is moved by means of the swivel arm 18 , the light guide 26 is only moved along the traverse 14 with its end arranged in the carriage 17 . The pivoting arm 18 can rotate, which has no effect on the position of the light guide 26 . This makes it possible for the swivel arm 18 to be able to complete one or more complete revolutions without the functionality of the light guide 26 being impaired as a result, since it is not carried along during such a rotary movement of the swivel arm 18 .

With such an arrangement, a large number of processing heads 13 can be provided, each by means of a swivel arm on a carriage 17 that can be moved along the traverses 14, with it being ensured that the individual light guides 26 cannot become tangled with one another. This makes it easy to create a 3D printer 1 which has at least eight, preferably at least twelve and in particular at least sixteen processing heads, all of which can be subjected to a light beam bundle 24 simultaneously or quasi-simultaneously.

The light sources 25 can generate the light beam in continuous operation (cw) or in pulsed operation (pw). In the case of a pulsed light source 25 with a high light intensity, it can also be expedient to assign a light source 25 to a plurality of processing heads 13, in which case a multiplexer is then installed between the light source 25 and the respective bear processing heads 13 is arranged, so that the light beam generated by the light source is clearly one of the multiple processing heads 13 fed to the multiplexer. The change between the individual processing heads 13 can take place so quickly that the change is so quick compared to the melting or sintering process that the individual processing heads 13 coupled thereto can be regarded as being acted upon more or less simultaneously by a light beam 24 .

Another embodiment of the swivel arm ( 3d ) has a pumped laser with a light pump 32 and a resonator 33 as the light source, which are connected to one another via an optical fiber 34 . The resonator comprises an active medium, which preferably consists of a solid body and which is excited or pumped by means of pumped light 35 emitted by the light pump 32 .

The resonator 33 is arranged together with the optical lens 23 directly at the end of the swivel arm 18 remote from the swivel axis 20 in such a way that a light beam 24 can be emitted vertically downwards. The light pump 32 is arranged on the carriage 17 in such a way that it does not participate in the pivoting movement of the pivoting arm. The light pump 32 typically includes one or more semiconductor lasers and a heat sink with cooling fins. The light pump is much heavier than the resonator 33 and the optical lens 23. Since only the resonator 33 and the optical lens 23 are moved and not the light pump 32, the rotational moment of inertia of the swing arm 18 is small.

In this embodiment, the light pump 32 is arranged on the carriage 17 . However, the light pump 32 can also be arranged independently or at a distance from the carriage 17 .

This embodiment can also be modified in that, instead of the light guide 34, a beam guide with reflector elements is provided, as is shown in 3c is shown. Then the light guide 34 can either be omitted completely or only guided up to the carriage 17 when the light pump is arranged away from the carriage 17 .

An ND:YAG laser is preferably used as the pumped laser and one or more laser diodes with a wavelength of 808 nm are used as the light pump. However, another laser such as a Yb:YAG laser can also be provided.

According to another embodiment ( 3e ) is a beam guide from the light source 25 to the swivel arm 18 by means of a light guide 26 is formed. The light guide 26 is guided from the light source 25 to the swivel arm 18 , the light guide 26 being arranged with its end remote from the light source 25 below the swivel arm 18 in the region of the carriage 17 . The light guide 26 is connected to the swivel arm 18 in such a way that the light guide 26 is guided along the swivel arm in the area of the carriage 17 and its end remote from the light source 25 points towards the free end of the swivel arm 18 . At the free end of the pivot arm 18, a reflector element 28 is arranged, which is designed as a mirror. However, the reflector element 28 can also be represented by other optical elements that deflect a light beam 24, such as a prism or the like.

A light beam 24 emitted by the light source 25 is transmitted by the light guide 26 and emitted at its end remote from the light source 25 in such a way that the light beam 24 is directed along the swivel arm 18 towards the reflector element 28, preferably parallel to the swivel arm. The second reflector element 28 is arranged at the free end of the swivel arm 18 and deflects the light beam 24 downward onto the processing area. Optionally, an optical lens 30 for focusing the light beam 24 can be provided in the beam path between the end of the light guide 26 and the reflector element 28 . Instead of the optical lens 30, a lens can also be provided in order to be able to change the degree of bundling of the light beam 24 and/or the reflector element 28 can be designed with a corresponding curvature.

When the processing head 13 is moved by means of the swivel arm 18, only the end of the light guide 26 remote from the light source 25 is carried along. In this embodiment, the swivel arm 18 can be designed to be particularly light, since only small loads have to be absorbed. A correspondingly designed swivel arm 18 has only a low rotational moment of inertia, so that it can be quickly swiveled to any rotational position. The carriage 17 can also be moved particularly quickly due to the low weight of the swivel arm 18 .

With such an arrangement, a large number of processing heads 13 can be provided, each by means of a swivel arm 18 on a carriage 17 that can be moved along the traverses 14, with it being ensured that the individual light guides 26 cannot become tangled with one another. This makes it easy to create a 3D printer 1 which has at least eight, preferably at least twelve and in particular at least sixteen bears processing heads 13, all of which can be acted upon simultaneously or quasi-simultaneously with a light beam 24.

In the present exemplary embodiment, the traverses 14 and thus also the swivel arms 18 attached thereto are arranged at different levels ( 1 : central traverse higher than the lateral traverses), so that the pivoting arms 18, which are arranged on the central traverse 14, cannot collide with the pivoting arms 18, which are arranged on the outer traverses 14. The level of the pivoting arms 18 can also be designed differently if all the traverses are arranged at the same height. This can be accomplished, for example, in that the swivel joints 19 are attached to the individual carriages 17 at different heights.

In the exemplary embodiment explained above, the traverses 14 are stationary. Within the scope of the invention, however, it is possible that the traverses can be moved horizontally and transversely to their longitudinal direction. However, such a design of the movement device 12 requires a more complex control, so that the individual swivel arms 18 do not collide. Therefore, the arrangement with stationary trusses 14 is generally preferred. Such a design of the movement device 12 allows for a simple scaling of the 3D printer, for example by attaching additional carriages to the existing traverses or by attaching one or more additional traverses in order to increase the production speed.

In the exemplary embodiment explained above, the swivel arms 18 cannot be adjusted in the vertical direction. Within the scope of the invention, however, it is possible either to provide a device for adjusting the vertical position of the swivel arm 18 on the carriage 17 or to design the traverses 14 and/or the entire movement device 12 to be adjustable in the vertical position. This can be particularly useful in order to create sufficient space for the movement of the squeegee between the powder bed 3 and the swivel arms 18 when squeegeeing the powder bed 3 using the squeegee 9 and after the squeegee 9 is again outside the area of the powder bed 3, the Swivel arms 18 are lowered in order to be as close as possible to the surface of the powder in the powder bed 3 with the processing heads 13 .

The light sources 25 for the individual processing heads 13 can be of identical design and each produce a light beam bundle with the same intensity and the same frequency or the same frequency range. However, it is also possible within the scope of the invention to provide different light sources for the different processing heads, with which light is emitted with different frequencies or frequency ranges and/or with different intensities. Light sources can also be provided with which the wavelength of the light can be tuned over a specific range. Such frequency-tunable lasers are known and usually have a semiconductor amplifier.

One advantage of the present invention is that the multiple processing heads 13 can simultaneously apply light and thus heat to different locations of the powder 11 in the powder bed 3 and simultaneously melt or sinter it. As a result, the manufacturing process is parallelized and significantly accelerated compared to conventional 3D printers. A 3D component 31 ( 1 ) be generated.

The processing heads 13 can be positioned very precisely over the powder bed 3, as a result of which highly precise 3D components can be manufactured.

The movement device 12 for the processing heads 13 is of very simple design and can be produced much more cost-effectively in comparison to 3D printers with a similar level of performance.

A first embodiment of a second exemplary embodiment is explained below. Like the first exemplary embodiment, the second exemplary embodiment comprises a process chamber 2, a powder bed 3, a squeegee 9 and at least one processing head 13. Identical parts of the second exemplary embodiment are denoted by the same reference symbols as in the first exemplary embodiment. The above explanations apply to the same parts, unless other statements are made below. The process chamber 2 can have a device for supplying an inert gas atmosphere in order to avoid oxidation of the powder 11 during component production.

A processing table 36 with a table top 37 is provided in the process chamber 2 . The processing table 36 has tempering channels 38 in order to temper the table top 37, also called the bearing surface, to a desired temperature. By controlling the temperature of the table top 38, stresses in the component, in particular in the first component layers, can be reduced or completely eliminated or prevented.

In the process chamber 2, the processing head 13 is mounted on a moving device 12 (in 4 not shown) provided to direct a light beam 24 onto the processing table 36. However, the processing head 13 can also be stationary and the light beam bundle emitted by the processing head can be directed to any desired point in the powder bed 3 with a deflection device which has, for example, two movable mirrors.

Instead of a single processing head 13, a moving device 12 with a plurality of processing heads 13 can also be provided, as is shown in FIGS 1 until 3d is shown.

An application dispenser 39 is provided in the process chamber, which has a storage chamber 40 for powder 11 and a closable application opening 41 through which the powder 11 can leave the storage chamber 40 for application to the processing table 36 . The application dispenser 39 has a squeegee 9 for smoothing out the powder 11 applied in the powder bed 3 .

The processing table 36 is surrounded by a wall 42 in the horizontal direction. The wall 42 encloses the table top 37 of the processing table 36 with little play.

The wall 42 is connected to a base 44 of the 3D printer 1 via a plurality of lifting cylinders 43 . The lifting cylinders 43 can adjust the height of the wall 42 relative to the processing table 36 in the vertical direction. The wall 42 can thus protrude a little upwards at the side of the processing table 36 and thus delimit a cavity which forms the powder bed 3 . The processing table 36 may be connected to the foundation 44 via isolators to reduce or prevent the transmission of shock and vibration to the processing table 36 .

The order dispenser 39 is coupled to a movement mechanism (not shown) with which the order dispenser 39 can be moved horizontally across the processing table 36 and thus parallel to the table top 37 of the processing table 36 . The movement mechanism of the order dispenser 39 is coupled to the wall 42 in such a way that the movement mechanism is raised or lowered together with the wall 42 . As a result, a lower edge 45 of the doctor blade 9 is always at the level of an upper edge 46 of the wall 42.

The height adjustment of the wall 42 can be coupled with other components in the process chamber. The machining head 13 can also be moved together with the wall 42 in this way. In this way, the vertical distance between the processing table 36 and the processing head 13 or between the processing head 13 and the wall 42 remains constant for each component layer to be manufactured. The bundle of light beams 24 then does not have to be refocused onto the production level before each production of a further component layer. The process control of the component production can be accelerated as a result.

The wall 42 may be provided with an outwardly horizontally projecting collar 47 at its upper edge to prevent powder from falling onto the foundation in areas not intended for it. The collar 47 can only be provided on one side of the powder bed 3 or can be formed on several or even circumferentially.

A collecting device, embodied as a collecting basin 48, is arranged around the processing table 36 or around the collar 47, in order to collect excess powder 11 which, for example, is removed from the processing table 36 or from the collar 47 by the squeegee 9. The collection basin 48 is connected to a suction device 49 which supplies the collected powder 11 to a filter 50 . Particles larger than a certain grain size are retained in the filter 50, for example particles with a grain size of more than 120 μm. Particles to be filtered out accordingly can be, for example, dirt particles or powder particles that are already connected to one another. The powder material filtered in the filter 50 is then fed via a supply line 51 to the order dispenser 39 for reuse. In this way, a recirculating circuit is created, through which excess powder 11 can be reused, as a result of which material savings can be achieved.

In this embodiment, the processing table 36 can be designed in a particularly simple and therefore cost-effective manner, since the processing table 36 does not have to be moved. In the additive manufacturing of components, the processing table 36 must be designed to carry high loads due to the high material density. For example, if the processing table has a support surface of 1.5 mx 1 m and a stroke of 0.5 m, this results in a working volume of 0.75 m ³ . If this working volume is filled with aluminum powder, the content weighs around 2 t. In the case of steel powder, the weight is around 6 t. The components to be moved, such as the wall 42 and possibly other components (order dispenser 39, squeegee 9, processing head 13), are significantly lighter than a processing table 36 with a large working volume. Therefore it is possible to use these components to move with a significantly smaller dimensioned drive, whereby the acquisition costs but also the operating costs can be reduced. At the same time, the structure of the 3D printer 1 is also simplified.

In 4 the process chamber 2 is shown at the beginning of the additive manufacturing of a component. To apply the powder 11 to the processing table 36, the application dispenser 39 moves in the direction of movement 10 over the entire processing table 36. The applied powder 11 is smoothed out by the squeegee 9. The first component layer can then be formed by a light beam 24 . After the production of the first component layer, the wall 42 is moved upwards by the height of the first component or powder layer. The order dispenser 39 is coupled to the wall 42 by the same height upwards. The aforementioned steps are then repeated until the component is completely manufactured. The wall 42 forms, together with the processing table 36, a powder bed 3 that grows with the height.

The wall 42 can be moved depending on the thickness of the next component layer to be formed. It is possible for the component layers to each have different thicknesses. During production, individual component layers can be made thicker than others if high molding accuracy is not important in the corresponding component areas. In this way, the component production can be accelerated in individual component areas and thus also take place particularly quickly overall. If, on the other hand, a high degree of dimensional accuracy is required in individual component areas, the component layer to be manufactured can have a small thickness. The component can thus be manufactured particularly quickly, depending on the dimensional accuracy required in the respective areas.

According to a second embodiment of the second exemplary embodiment, the movement device 12 for the processing head or heads 13 can be mechanically decoupled from the wall 42 so that both can be moved independently of one another ( 5 ). The machining heads 13 are each connected to a traverse 14 via a swivel arm 18 , a swivel joint 19 and a carriage 17 . In contrast to the first exemplary embodiment, a vertical movement device is provided on the carriage 17, so that the machining head is arranged so that it can move in the vertical direction. In 5 only a single processing head 13 is shown for a simpler visual representation.

The processing head 13 has an optical lens 23 in order to focus the light beam 24 emitted by it onto the surface of the powder bed. Three distance sensors 52 are stationarily arranged in the process chamber 2 . The distance sensors 52 are designed for electro-optical distance measurement between the distance sensors 52 and the processing head 13 . To measure the distance between the distance sensors 52 and the processing head 13, a reference element 53, for example a reflector, in particular a prismatic reflector, for optical beams 54 is arranged on the processing head 13. ,

The distance sensors 52 are stationarily but pivotably arranged in the process chamber 2 so that a respective optical beam bundle 54 emitted by the distance sensor 52 can track the reference element 53 . The distance sensors 52 are connected to a control and regulation device 55 . From the three measured distances between the processing head 13 and the three distance sensors 52, the spatial position of the processing head 13 can be determined exactly. With the help of the control and regulation device 55, the machining head 13 can be moved precisely into a desired position in three-dimensional space. The positioning of the processing head 13 is regulated via the distance measurements.

This makes it possible to decouple the movement of the processing head 13 from the movement of the wall 42 and still focus the emitted light beam 24 exactly onto the surface of the powder bed.

One or more reference elements 53 are preferably provided on the wall 42, in particular its upper edge, which can be scanned by the distance sensors in order to determine the height of the wall 42. In this way, the relative position of the processing head(s) 13 and the wall 42 can be detected.

Instead of detecting the height of the wall 42, the height of the powder bed 3 can also be scanned with a suitable sensor. Then the processing heads 13 can be aligned directly with respect to the height of the powder bed 3 .

The drive with which the carriage 17 and the swivel joint 19 are moved is controlled by the control and regulation device 55 as a function of the current position of the machining head 13 . For this purpose, the processing head 13 can be moved more slowly the closer it comes to its target position. In this way, the machining head 13 can also be transferred exactly into a desired position with a cheap and not very precise movement device 12 per se Accuracy of the position is determined solely by the distance measurement using the distance sensors 52. In this way, the overall costs of the 3D printer 1 can be reduced since the distance sensors 52 are inexpensive and at the same time a more cost-effective movement device 12 or a more cost-effective drive can be used.

the inside 5 The structure shown for controlling and regulating a processing head 13 can also be used to precisely position other components, for example a squeegee 9, an application dispenser 39, a wall 42 or any other movable component with the aid of a control loop.

In the second exemplary embodiment, optical distance sensors 52 are used to measure the distances between the reference elements 53 and the distance sensors 52 . Such distance sensors 52 are inexpensive and have a very high resolution. You can use triangulation to determine the distance to the reference element 53. During the triangulation, an optical bundle of rays 54, for example a laser beam, is focused on the measurement object and observed with a camera located next to it in the distance sensor 52, a spatially resolving photodiode or a CCD line. If the distance between the measurement object and the sensor changes, the angle at which the point of light is observed also changes, and with it the position of its image on the photo receiver. The distance of the object from the laser projector is calculated from the change in position with the help of angle functions. Distance measurement using triangulation is very simple and inexpensive. If the requirements for accuracy are low, the radiation from a light-emitting diode can also be used as the light beam bundle.

The distance can also be measured by measuring the phase position. When measuring the phase position, an optical beam 54, for example a laser beam, is emitted. The phase shift of the reflected laser beam compared to the emitted beam depends on the distance. This phase shift can be measured and used to determine the distance traveled. The distance measurement by measuring the phase position has a high level of accuracy.

When measuring distance over the transit time, a short light pulse, a constant light beam or a light modulation is emitted. The pulse transit time is the time it takes for the light beam to travel from the source, to a reflector, and back to the source. By measuring this transit time, the distance between the source and the object can be determined using the speed of light. Sensors that scan lines or areas or planes, such as stereo cameras for the three-dimensional localization of one or more objects, can also be used to measure the distance. Corresponding sensors do not have to be pivotable due to their large recording area.

The aforementioned distance sensors 52 are manufactured and sold, for example, by the company Micro-Epsilon.

Instead of optical sensors, other sensors, such as ultrasonic sensors or sensors that determine the distance using the propagation time of radio waves, can also be used.

Regardless of the type of sensor, the advantage is that the position of the processing heads can be set very precisely thanks to the control loop. This can also be used to determine the position of the machining heads that can only be moved in one plane according to the first exemplary embodiment.

For precise positioning, the actual position of the movable component, for example the processing head 13, can be recorded after the start ( 6 ). For this purpose, the distance between the processing head 13 and the respective distance sensor 52 can be measured. The actual position is detected by measuring the distance using the distance sensors 52 5 . The actual position of the processing head can be determined in a simple manner from the three distance measurements. If the actual position corresponds to the target position, no further action is required and the component production can be continued.

The position of the movable component, for example the machining head 13, can be determined absolutely in space. However, the position of the movable component can also be determined relative to another component. In the latter case, the distance between the two components is determined.

The actual position of the moving component can be controlled individually and sequentially in each spatial direction or in relation to each axis until the target position is reached. However, it is also possible to simultaneously regulate the position of the movable component in all three spatial directions or in relation to all axes.

The distance sensors 52 can be stationary in the process chamber 2 of the 3D printer 1, anord net, for example the distance sensors 52 can be connected to the foundation 44 of the 3D printer 1 via a carrier. The distance sensors 52 can determine the position of the surface of the powder bed 3 via a distance measurement and then determine the position of a movable component, for example a processing head 13, with the aid of a further distance measurement. Depending on the position of the powder bed 3, ie the height of the powder bed 3, the processing head 13 can be moved into a desired position in order to set a required distance between the processing head 13 and the surface of the powder bed 3. One or more machining heads 13 can be moved to their desired position with the aid of the control and regulation device 55 described above. It is also possible for one or more distance sensors 52 to be connected to or arranged on a processing head 13 and for the distance between the processing head 13 and the powder bed surface to be determined directly in order to then move the processing heads 13 to a target distance from the surface of the powder bed 3 proceedings.

If the actual position does not correspond to the target position, then the position of the processing head 13 is modified. For this purpose, a drive can be started and the traversing speed of the processing head 13 can be adjusted as a function of the distance between the actual position and the target position. The smaller the distance between the actual position and the target position, the lower the traversing speed that can be selected. After a fixed unit of time and/or a defined distance covered, the actual position can be recorded again and then modified if necessary. It is also possible to record the actual position continuously. In this way, a closed control loop can be created. This regulation makes it possible to move the processing head 13 exactly into a desired position with a simple, inexpensive and not very precise movement device 12 . The accuracy of the positioning is determined solely by the distance measurement using the distance sensors 52 .

In addition, it is also possible for the position of the processing heads 13 to be adjusted as a function of the position of the movable wall 42, in particular an upper edge and/or a horizontal surface. For this purpose, at least one distance sensor 52 can be connected to the processing heads 13 or arranged in a stationary manner in the 3D printer 1 .

Instead of the position of one or more processing heads 13, the position of a traverse 14 or another component of a movement direction 12, for example a carriage 17, can be determined and positioned relative to the movable wall 42 or the surface of the powder bed 3. For this purpose, the traverse 14 can have one or more distance sensors 52 and measure the distance to the surface of the powder bed 3 .

A squeegee 9 can also be positioned relative to the powder bed surface or a movable wall 42 in the same way. One or more distance sensors 52 can then be connected to the squeegee 9 and/or arranged in a stationary manner in the process chamber 2 .

It is also possible to position an order dispenser 39 depending on the position of the movable wall 42 or the surface of the powder bed 3 . For this purpose, the order dispenser 39 can have at least one distance sensor 52 and/or at least one distance sensor 52 can be arranged stationarily in the process chamber 2 of the 3D printer 1 .

The movable wall 42 can also be moved relative to the surface of the powder bed 3, for example to a position which is higher than the powder bed 3 by a layer thickness. To this end, it is advantageous if the distance sensors 52 are arranged in a stationary manner in the process chamber 2 and determine the distance between the movable wall 42 and the surface of the powder bed 3 .

In addition, it is also possible to move a supply cylinder 4 relative to a processing table. In known 3D printers 1, the processing table 36, designed as a production piston 7, can also be moved in a controlled manner. For example, after the completion of a component layer, the production piston can be lowered by a defined layer thickness in order to be able to apply a new layer of powder. The distance sensors 52 are then preferably arranged in a stationary manner in the process chamber 2 of the 3D printer 1 .

It is also possible for several moving components to be moved together coupled to one another. For example, a squeegee 9 together with one or more processing heads 13 and/or together with an order dispenser 39 can be positioned in a controlled manner at a distance from the surface of the powder bed 3 that is required in each case in the vertical direction. The vertical distance between the squeegee 9 and the processing heads 13 and/or the order dispenser 39 is then the same at all times.

Another embodiment of a third exemplary embodiment is explained below. Identical parts of the third exemplary embodiment are denoted by the same reference symbols as in the first and second exemplary embodiment. The above explanations apply to the same parts, unless other statements are made below.

A glass plate 56 is arranged horizontally in the process chamber 2 as a table top 37 of the processing table 36 . A moving device 12 for moving a plurality of processing heads 13 is provided below the glass plate 56 .

The movement device 12 comprises three crossbeams 14 which extend transversely below the glass plate 56 . The traverses 14 are arranged parallel to one another. In the present exemplary embodiment, the middle traverse 14 is arranged somewhat lower than the two outer traverses 14 .

The movement device 12 has, as in the 1 and 2 described, on each traverse 14 has two carriages 17 each with a swivel arm 18 . At least one machining head 13 is arranged on each of the swivel arms 18 . The swing arm 18 can as in the 3a-3d be trained.

In the process chamber 2, a supporting body 57 is arranged above the glass plate, on the underside 58 of which the component is manufactured. The first component layer is formed on the underside 58 and can be connected to the support body 57 . The support body 57 can be moved or adjusted together with the component 31 in the vertical movement direction 59 . For this purpose, a lifting device 60 for gripping and lifting the component 31 can be provided.

For the additive manufacturing of a 3D component 31, powder 11 of one in 6 Order dispensers 39 (not shown) can only be placed on the entire glass plate 56 . The glass plate 53 serves as a support surface for the powder 11. The powder can be drawn from an in 6 Not shown squeegee 9 are smoothed, whereby a powder layer 61 is formed. The supporting body 57 is then placed on the powder 11 . The powder 11 is then selectively melted or sintered with the aid of the light beams 24 emitted by the processing heads 13 and connected to form a component layer. The component layer can then be connected to the support body. The component layer is then raised together with the supporting body 57 . The lifting device 60 can be used to support the gripping and lifting of the component layer. The unused powder 11 can then be removed from the glass plate 56 in order to prevent individual powder grains which are connected to one another from being used in the manufacture of the next component layer. The order dispenser 39 can then deposit powder 11 again on the glass plate and a new powder layer 61 can be formed. The component is then placed on the new powder layer 61 . The powdered material is melted or sintered, forming a new component layer that is simultaneously bonded to the previous component layer. The above steps are repeated until the component 31 is completely manufactured. The component 31 is manufactured in this way from top to bottom.

Reference List

1

3D printer

2

process chamber

3

powder bed

4

storage cylinder

5

storage flask

6

Reciprocating/cylinder unit

7

production pistons

8th

Reciprocating/cylinder unit

9

squeegee

10

direction of movement

11

powder

12

moving device

13

processing head

14

traverse

15

long side face

16

rail profile

17

Sleds

18

swivel arm

19

swivel joint

20

pivot axis

21

light guide

22

End

23

optical lens

24

light beam

25

light source

26

light guide

27

reflector element

28

reflector element

29

passage opening

30

optical lens

31

3D component

32

light pump

33

resonator

34

light guide

35

pump light

36

processing table

37

tabletop

38

tempering channel

39

order dispenser

40

pantry

41

order opening

42

wall

43

lifting cylinder

44

foundation

45

bottom edge

46

edge

47

collar

48

reservoir

49

suction

50

filter

51

supply line

52

distance sensor

53

reference element

54

beam bundle

55

control and regulation device

56

glass plate

57

supporting body

58

bottom

59

direction of movement

60

lifting device

61

powder layer

QUOTES INCLUDED IN DESCRIPTION

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

Patent Literature Cited

• DE 102016222068 A1 [0002]
• WO 2018/202643 A1 [0003]
• US 10399183 B2 [0004]
• US10399145B2 [0005]
• US 2015/0283612 A1 [0006]
• US 2014/0198365 A1 [0006]
• JP 2009006509 A [0006]
• DE 10053742 C5 [0007]
• US9011136B1 [0007]
• CN 206065685 U [0007]

Claims (25)

Device for the additive manufacturing of components, in particular by means of selective melting or sintering, with a light source (25) for generating a light beam (24), a processing head (13) which is coupled to the light source (25) either with a beam guide, so that the light beam (24) is guided to the processing head (13), or the light source (25) is arranged directly on the processing head (13), so that a light beam (24) can be directed from the processing head (13) onto a processing area, the processing head (13) is movably mounted so that the light beam (24) can be directed to different points in the processing area, characterized in that a plurality of processing heads (13) are provided for respectively directing a light beam (24) to the processing area, and the processing heads each are arranged on a carriage (17) which can be moved along a traverse (14). device after claim 1 , characterized in that the processing heads (13) are each arranged by means of a pivotable swivel arm (18) on one of the slides (17). device after claim 2 , characterized in that at least along the swivel arms (18) the beam guidance for the respective light beam (24) is formed by means of reflector elements (27, 28). device after claim 2 or 3 , characterized in that the swivel arms (18) are made of plastic, in particular fiber-reinforced plastic, and/or a reflector element (28) for directing the respective light beam (24) onto the processing area is provided at each end remote from a swivel axis (20). . Device according to one of claims 2 until 4 , characterized in that one of the light sources (25) or one resonator (33) of a laser serving as the light source (25) is arranged on the free ends of the swivel arms (18) remote from an axis of rotation (20). Device according to one of Claims 1 until 5 , characterized in that a plurality of beam guides are provided and are designed at least partially as light guides (21, 26). Device according to one of Claims 1 until 5 , characterized in that several traverses (14) arranged parallel to one another and in one plane are provided. device after claim 7 , characterized in that the traverses (14) are stationary. Device according to one of Claims 1 until 8th , characterized in that on each traverse (14) at least two independently movable carriages (17) are mounted, each carriage (17) having a processing head (13). Device according to one of Claims 1 until 9 , characterized in that a plurality of light sources (25), in particular an array of light-emitting diodes and/or semiconductor lasers, are provided, each light source (25) being assigned to one or more processing heads (13). Device according to one of Claims 1 until 10 , characterized in that a multiplexer for distributing the light beam of one of the light sources (25) to different beam guides, which each lead to one of the processing heads (13), is provided. Device according to one of Claims 1 until 11 , characterized in that a control device is provided which is designed in such a way that a plurality of machining heads (13) can be moved simultaneously and/or a light beam (24) can be applied to them simultaneously. Device according to one of Claims 1 until 12 , characterized in that a powder bed (3) is provided, which forms the processing area. Device for the additive manufacturing of components, in particular by means of selective melting or sintering, preferably according to one of Claims 1 until 13 , with a processing table (36) with a preferably horizontal table top (37) which forms a support surface for a powder bed (3), the processing table (36) having a wall (42) at least partially laterally delimiting the table top (37), and wherein the table top (37) and the wall (42) together define the processing area, characterized in that the wall (42) can be moved preferably perpendicularly to the table top (37). device after Claim 14 , characterized in that the wall (42) can be moved together with at least one other component, preferably a light source (25) and/or a processing head (13) and/or a squeegee (9) and/or an order dispenser (39) and/or a storage cylinder (4). Device according to one of Claims 1 until 15 , characterized in that an application dispenser (39) for applying powder (11) to be selectively melted or sintered to the table top (37) is provided. Device according to one of Claims 1 until 16 , characterized in that a collection device is provided, preferably designed as a collection basin (48) to collect excess powder (11) that has escaped from the processing area. device after Claim 17 , characterized in that a suction device (49) and a filter (50) are provided in order to be able to suck off the excess powder, filter it and reuse it. Device for the additive manufacturing of components, in particular by means of selective melting or sintering, preferably according to one of Claims 1 until 18 , with at least one movable component, preferably a processing head (13) and/or a processing table (36) and/or a wall (42) and/or a squeegee (9) and/or an application dispenser (39), and a drive for Method of moving component, characterized in that at least one distance sensor (52) is provided for preferably electro-optical distance measurement. device after claim 19 , characterized in that the distance sensor (52) is arranged stationary to measure the distance between the distance sensor (52) and the movable component. device after claim 19 or 20 , characterized in that a control and regulation device (55) is provided, which is designed such that the movable component can be moved into a desired position depending on the measured distance between the distance sensor (52) and the movable component. Device according to one of claims 19 until 21 , characterized in that two, preferably three, distance sensors (52) are provided for distance measurement between the distance sensors (52) and the movable component in order to determine the spatial position of the movable component. Device according to one of claims 19 until 22 , characterized in that at least three distance sensors (52) and at least two movable components are provided, each component being detectable in any position by at least three distance sensors (52) for distance measurement. Device according to one of claims 19 until 22 , characterized in that each movable component is permanently assigned three distance sensors (52) for distance measurement. Device for the additive manufacturing of components, in particular by means of selective melting or sintering, preferably according to one of Claims 1 until 13 , with a glass plate (56) whose surface forms a supporting surface for powder (11), a processing area above the glass plate (56), a light source (25) for generating a light beam (24), a processing head arranged below the glass plate (56). (13), which is either coupled to the light source (25) with a beam guide so that the light beam (24) is guided to the processing head (13), or the light source (25) is arranged directly on the processing head (13) so that a light beam (24) can be directed from the processing head (13) through the glass plate (56) to the processing area, the processing head (13) being movably mounted so that the light beam (24) can be directed to different points in the processing area, thereby characterized in that a plurality of processing heads (13) are provided for respectively directing a light beam (24) through the glass plate (53) onto the processing area, where in which the processing heads (13) are each arranged on a carriage (17) which can be moved along a traverse (14).

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