Apparatus for additive manufacturing of parts by particularly selective melting or sintering.

Abstract

The present invention relates to an apparatus for additive manufacturing of parts, in particular by selective melting or sintering, comprising a light source for generating a light beam bundle and a processing head, the processing head being either coupled to the light source by a beam guide so that the light beam bundle is guided to the processing head, or being arranged directly on the processing head so that the light beam bundle is guided from the processing head onto the processing area, the processing head being movably mounted so that the light beam bundle can be directed to a desired position on the processing area. The invention is characterized in that a plurality of processing heads are provided for directing the light beam bundle respectively onto the processing area, the processing heads being arranged respectively on carriages movable along a traverse. This allows powder to be melted or sintered at several locations simultaneously. Preferably, the processing heads are arranged on a pivoting arm. This makes the design of the apparatus very simple and cost-effective.

Description

Technical Field

[0001] The present invention relates to an apparatus for performing additive manufacturing of parts, particularly by selective melting or sintering.

Background Art

[0002] Patent Document 1 describes an apparatus and method for performing additive manufacturing of parts using a plurality of spatially separated steel guides. The processing head includes a plurality of optical switching elements that can be used to direct a plurality of beams to a target position. The processing head is adjustably arranged on a linear axis. This linear axis is adjustably attached to a linear axis orthogonal thereto. Thereby, X-Y movement becomes possible. One or more laser beam sources are attached to the linear axis.

[0003] Patent Document 2 discloses an apparatus for additive manufacturing by selective laser sintering. One or more lasers are assigned to one or more laser heads. These lasers are distributed to individual heads via a beam splitter. The heads can move in the X and Y directions via rails. The heads can move independently of each other. The supply of light to the heads is realized by mirrors.

[0004] Patent Document 3 describes a layered manufacturing process in which a laser beam is supplied to an optical head via an optical fiber. Thereby, a plurality of laser beams can be directed to the same head and emitted in parallel. Thereby, melting points parallel to the surface of the powder bed can be formed.

[0005] A similar method is described in Patent Document 4.

[0006] Patent documents 5-7 describe a selective laser sintering apparatus characterized by multiple optical heads capable of directing a laser beam onto a powder bed. These heads cannot move themselves in the X and Y directions, but they direct the laser beam to the appropriate position via mirrors. The advantage here is that the laser's focal point can be changed rapidly. However, the heads must be relatively far from the powder bed, limiting the area that can be irradiated.

[0007] Patent documents 8 and 9 describe a sintering apparatus having a cross-slide arrangement, an additive manufacturing process having multiple heads for plastic printing, and an apparatus having a head with both 3D printing and 3D cutting elements.

[0008] Patent Document 10 discloses an apparatus and method for selective laser melting, which includes multiple parallel-operating laser heads for melting a material according to powder bed-based laser melting. Each of the laser heads is movable along a linear traverse, and the laser heads can be moved independently of each other. In this way, the array of laser heads and the surface of the powder bed can be rotated horizontally relative to each other.

[0009] Patent document 11 describes an apparatus and method for additive manufacturing of parts, the apparatus comprising a plurality of robotic arms, each of which is fitted adjacent to the other, with a deposition head and a laser head. Each robotic arm is equipped with at least one swivel joint and is designed to allow the deposition head and laser head to move in all three spatial directions. In this way, a material can be deposited onto the processing surface by the deposition head, and then this area can be directly melted by the laser.

[0010] Patent document 12 describes an apparatus comprising equipment for additive manufacturing and milling processes. This apparatus basically comprises multiple robotic arms and may be equipped with gripping elements or laser heads for supplying material onto a work platform or for removing finished parts. Each robotic arm has two joints and is mounted rotatably and pivotally. The apparatus further comprises a central manufacturing arm which can be equipped with a laser head or a milling head. The central manufacturing space can move linearly along a traverse.

[0011] Patent document 13 discloses a laminating apparatus equipped with two parallel-operating laser heads for melting a material according to a laminating process. Both laser heads are coupled to a traverse and can move linearly independently of each other. The traverse can also move. The processing area can be completely covered. The laser beams are guided to the processing area by a focusing unit using two mirror elements.

[0012] Patent document 14 discloses an apparatus and method for 3D printing, providing a laser for melting a raw material and a cutting laser for processing the resulting structure. The laser for melting the starting material and the cutting laser can move independently along multiple traverses in both the horizontal and vertical directions. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] German Patent Application Publication No. 102016222068 [Patent Document 2] International Publication No. 2018 / 202643 [Patent Document 3] U.S. Patent No. 10399183 [Patent Document 4] U.S. Patent No. 10399145 [Patent Document 5] U.S. Patent Application Publication No. 2015 / 0283612 [Patent Document 6] U.S. Patent Application Publication No. 2014 / 0198365 [Patent Document 7] Japanese Patent Application Laid-Open No. 2009-6509 [Patent Document 8] German Patent Application Publication No. 10053742 [Patent Document 9] U.S. Patent No. 9011136 [Patent Document 10] U.S. Patent Application Publication No. 2019 / 0009333 [Patent Document 11] U.S. Patent Application Publication No. 2017 / 0129012 [Patent Document 12] Chinese Patent Application Publication No. 106312574 [Patent Document 13] German Patent Application Publication No. 102018128543 [Patent Document 14] Chinese Utility Model Patent No. 206065685 [Summary of the Invention] [Problems to be Solved by the Invention]

[0014] The present invention is based on the object of creating an apparatus for performing additive manufacturing of components, in particular by selective melting or sintering, which is easy to design, has a high production speed, and can manufacture 3D components with high precision. [Means for Solving the Problems]

[0015] This object is solved by an apparatus having the features of claim 1, an apparatus having the features of claim 13, an apparatus having the features of claim 18, and an apparatus having the features of claim 24. Advantageous embodiments are specified in the dependent claims.

[0016] <00,00091>The apparatus according to the present invention for performing additive manufacturing of components, in particular by selective melting or sintering, is a light source for generating a light beam bundle, a processing head which is coupled to the light source by a beam guide so that the light beam bundle is guided to the processing head, or the light source is directly arranged on the processing head so that the light beam bundle is guided from the processing head onto the processing area, comprising the processing head is mounted at a movable position so that the light beam bundle can be directed to different positions in the processing area, a plurality of processing heads are provided for respectively directing the light beam bundle to the processing area, and the processing heads are respectively arranged on a carriage movable along a traverse.

[0017] The apparatus is characterized in that the processing heads are respectively arranged on one of the carriages by a swivel arm which can swivel around a vertical swivel axis.

[0018] By providing a plurality of processing heads, a plurality of light beam bundles can be simultaneously irradiated onto the processing area, so that a plurality of locations in the processing area can be melted or sintered in parallel. The processing heads are arranged on or in the carriage and can be moved along the traverse. Thereby, the positioning of the processing heads onto the processing area can be easily and surely achieved.

[0019] By providing swivel arms for processing heads that can swivel around a vertical pivot axis, each of which is mounted on a carriage, the processing heads can be quickly positioned at any desired location across a large section of the processing area. This section extends around a traverse, along which a specific carriage carrying each processing head can move within a region around the pivot axis of the swivel arm, extending on both sides by a width corresponding to the length of the swivel arm. Thus, this section is strip-shaped around the traverse, having a width corresponding to approximately twice the length of the swivel arm. This strip-shaped section is hereafter referred to as the cover region. This is because the processing heads mounted on the carriages of the traverse can be positioned at any location within the cover region, and at any location within the cover region, the beam of light can be directed into or cover the processing area.

[0020] A swivel arm can be designed to rotate only around a vertical axis. Such a design is much simpler than that of a multi-axis robot arm. Nevertheless, the processing head can be positioned very quickly and accurately, and high throughput is achieved through parallel processing.

[0021] The swivel arm can be designed to be, for example, at least 5 cm long, preferably at least 10 cm or at least 15 cm long, and particularly at least 20 cm long. The longer the swivel arm, the wider the coverage area.

[0022] As the swivel arm rotates the processing head away from the traverse, the position of the processing head in the direction parallel to the traverse becomes less precise. Therefore, it may be useful to position the processing head only within a limited angular range of the swivel arm. The angular range can be, for example, limited to a maximum swivel angle of 60° or 45° relative to the traverse. At a swivel angle of 45°, the width of the covered area is reduced to one length of the swivel arm.

[0023] The apparatus may comprise a plurality of traverses arranged parallel to each other. Preferably, the traverses are spaced apart so that their coverage areas overlap from adjacent traverses.

[0024] Along the swivel arm, beamlines for each beam beam can be formed by reflector elements. This results in a very lightweight swivel arm with a low moment of rotational inertia, allowing it to quickly rotate to any desired position.

[0025] The swivel arm is preferably made of plastic, particularly fiber-reinforced plastic. Mirrors can be provided at each end of the swivel arm, away from the axis of rotation, to direct each beam of light towards the processing area.

[0026] The beamline can be designed at least partially as a light guide. The light guide can extend from the light source to each processing head. However, each light guide can also simply be guided from the light source to a pivotably mounted end of each swivel arm, and positioned there using its end so that the beam of light is coupled to a beamline along the swivel arm, which is formed by a reflector element. Such an embodiment has the advantage that the swivel arm can be rotated more than 360° without rotating the light guide. The end of the light guide to which the light from the light guide is coupled to the beamline on the swivel arm can be stationary relative to the carriage to which the swivel arm is mounted.

[0027] Alternatively, the end of the light guide can be positioned stationary on the swivel arm so that the light beam is radiated in the direction of the free end of the swivel arm, preferably parallel to the swivel arm. A reflector element, such as a deflection mirror, can be provided at the free end of the swivel arm to direct each light beam onto the processing area.

[0028] The reflector element can be a parabolic mirror or a free-form mirror for combining light, eliminating the need for optical lenses in the beam path.

[0029] A traverse with a movable carriage can be positioned in a stationary location. This is particularly advantageous in relation to designs having a processing head positioned on a slewing arm. This is because such a stationary arrangement is much easier to control to avoid collisions between different slewing arms compared to a device where the slewing arm can swivel, the carriage can move along the traverse, and the traverse itself can move laterally relative to its longitudinal direction. Also, because the traverse and slewing arm are stationary on the carriage, it is possible to completely cover the processing area with only a few traverses, as long as the slewing arm is not too short. The processing head positioned at the free end of the slewing arm can be formed to be very lightweight, for example, by only a small mirror, so that a low moment of rotational inertia can be achieved even with a long slewing arm having a length of, for example, at least 10 cm, preferably at least 15 cm, and especially at least 20 cm.

[0030] This device can be designed to allow for the retrofitting of one or more traverses. In this way, the processing area can be expanded later, and the density of traverses, and therefore the density of processing heads, can be increased within a given processing area. When increasing the density of traverses and shortening the distance between traverses, it is useful to mount the slewing arms interchangeably on the carriage so that shorter slewing arms can be used if the distance between traverses is short.

[0031] Preferably, each traverse is fitted with at least two independently movable carriages, each carriage equipped with a processing head. More than two carriages, for example, three or four carriages, may be provided for a single traverse.

[0032] Preferably, multiple light sources are provided, and each light source is assigned to one or more processing heads. The light sources are preferably lasers, particularly CO2 lasers or ND:YAG lasers. CO2 lasers are mainly used for melting or sintering plastic powders, and ND:YAG lasers are mainly used for melting or sintering metal powders. For example, the optical output of such a CO2 laser is 30W to 70W, and the optical output of an ND:YAG laser is 100W to 1000W or more. Alternatively, the light sources may be light-emitting diodes, particularly superluminescent light-emitting diodes, and / or semiconductor lasers.

[0033] By providing multiple light sources and multiple processing heads that can be independently positioned within the processing area, 3D parts can be manufactured by simultaneously melting or sintering powder at multiple locations within the processing area. This simultaneous melting or sintering of powder significantly improves the production speed of additive manufacturing compared to conventional equipment. High production speeds can be achieved even if the processing heads remain in each position for a slightly longer time. Therefore, it becomes possible to use light sources with relatively low light output, which significantly reduces the cost of the equipment.

[0034] A multiplexer can be provided to distribute one of the light beams of a light source to different beamlines. Such a multiplexer is preferably useful for very high-intensity light sources that can melt or sinter powder in short pulses. The apparatus preferably has a powder bed in the processing area, in which powder to be selectively melted by the light beam can be placed.

[0035] The powder can be metal powder or plastic powder.

[0036] Individual swivel arms can be positioned at different heights to avoid collisions when moving them.

[0037] Individual light sources can be designed to emit light beams of different frequencies or different frequency ranges and / or different intensities. This allows for the individual control of selective melting and / or sintering processes. For example, this allows for the control of the porosity of the product manufactured by this process.

[0038] The optical beam can also be focused to different degrees within the processing area. This focusing can be adjusted, for example, by adjusting the height of the lens and / or processing head.

[0039] In the apparatus according to the present invention, powder can be melted or sintered simultaneously at multiple locations on the powder bed.

[0040] An inert gas atmosphere, particularly a nitrogen and / or argon atmosphere, can be formed throughout the entire apparatus. This inert gas atmosphere prevents oxidation of powders or parts during manufacturing. While the inert gas atmosphere is formed and maintained, contaminant particles can be filtered from inside the apparatus using a simple method.

[0041] According to another aspect of the present invention, an apparatus is provided for additive manufacturing of parts, particularly by selective melting or sintering, the apparatus having a processing table having a preferably horizontal table plate that forms a support surface for a powder bed, thereby the processing table having walls that are at least partially lateral to the table plate, and the table plate and walls together define a processing area. The apparatus is preferably characterized in that the walls are movable perpendicular to the table plate.

[0042] During the manufacturing of a part, after one or more part layers have been manufactured, the wall moves perpendicular to the processing table. For this purpose, at the start of part manufacturing, the upper side of the wall can form a flat surface with the table plate of the processing table. Powder is applied to the table plate and smoothed. The powder layer can have a thickness of approximately 20 μm to 100 μm. Then, a first part layer is created by binding at least some of the powder particles. Bonding can be done by melting and cooling, by sintering, or by local application of a binder. After the first part layer is created, the wall can be moved upward by the height of the first part layer. In this way, a chamber is formed between the wall and the support surface. A powder bed is formed within this chamber. The powder bed comprises the already formed part layer and the remaining unbound powder. Then, another powder layer can be applied and smoothed to manufacture a second part layer. The height of the wall can then be adjusted again according to the thickness of the second part layer. In this way, the chamber formed by the wall and the support surface is expanded vertically and comprises two part layers and the remaining unbound powder material. The above steps are repeated until the parts are completely manufactured. Generally, walls that are lighter than the processing table can be moved with less effort. Walls can be moved after one or more layers have been formed.

[0043] It is advantageous if the processing table is designed to be stationary and immovable. Therefore, the known setting, namely, the setting in which the processing table is moved downwards relative to a stationary wall surrounding it during part manufacturing, can be reversed. For additive manufacturing of parts, in a device with a processing table base area of ​​1.5m x 1m and a stroke of 0.5m, the working volume is 0.75m³. 3This means that when this working volume is filled with aluminum powder, the weight of the contents is approximately 2 tons. In the case of iron powder, the weight is approximately 6 tons. Typically, only the walls, which are much lighter than the processing table and the added products on it, need to be moved, allowing for the use of small, cost-effective drive units. At the same time, since the processing table does not need to be moved, the structure of the processing table can be designed to be particularly low-cost yet stable. This further reduces the overall cost of the equipment.

[0044] For vertical adjustment of the wall, for example, an electric, pneumatic, and / or hydraulic drive system can be used.

[0045] The wall may be provided with a collar projecting horizontally outward from its upper edge, thereby preventing powder from falling onto the foundation in unintended areas. This collar may be provided on only one side of the powder bed, or multiple collars or collars may be formed around the circumferential direction.

[0046] The wall may be formed from multiple wall sections, which can be moved individually and / or together. Furthermore, each wall section can be moved independently of the others. In this way, the wall can be adapted to a wide variety of possible uses.

[0047] A dispensing dispenser can be provided to apply a powder to be selectively melted or sintered onto a processing table or processing area. The dispensing dispenser is movable horizontally on the processing table and can distribute the powder across the entire processing area. The dispensing dispenser may have a roller with a scraper, or be coupled to a scraper, to smooth the applied powder. Using a dispensing dispenser eliminates the need for a supply cylinder, thus reducing the installation space or footprint of the apparatus. However, using a supply cylinder instead of a dispensing dispenser has the advantage of minimizing disturbances to the atmosphere inside the apparatus caused by the movement of the dispensing dispenser.

[0048] The wall can be movable together with at least one other component, preferably a light source and / or a processing head and / or a scraper and / or a dispensing dispenser and / or a supply cylinder for applying powder material. It is particularly advantageous if the processing head can be height-adjusted along the wall. This ensures that the processing head is always at the same distance from the surface of the processing area or powder bed. This eliminates the need for time-consuming adjustment of the optimal distance between the processing head and the processing area, and the need for new focusing or adjustment of the optical characteristics of the processing head. Depending on the structure of the apparatus, it is known to those skilled in the art during component manufacturing which components are preferable to be at a certain distance from or from the wall or processing area. These components can be designed to be movable coupled to the wall. In this case, only one drive mechanism is needed to move these components relative to the processing table, simplifying the structure.

[0049] The walls can be moved according to the thickness of the next component layer to be formed. Individual component layers can also have different thicknesses. For example, if high molding precision is not required in a corresponding component area, individual component layers can be thicker than other component layers during manufacturing. On the other hand, if high molding precision is required in an individual component area, the thickness of the manufactured component layer can be reduced. In this way, the production of individual component areas, and ultimately the entire component, can be accelerated. Therefore, components can be manufactured particularly quickly according to the dimensional precision required in each area.

[0050] In a preferred embodiment, a recovery device is provided, preferably in the form of a recovery tank, to recover excess powder discharged from the processing area. During production, powder can be discharged from the processing area, for example, by being pushed from the processing table or tabletop, or from the collar by a scraper. This excess powder can be recovered by the recovery device. In a particularly simple embodiment, the recovery device may be formed by a recovery tank into which the excess powder falls. This excess powder can then be recovered and reused. The recovery tank may be partially or completely positioned around the workbench, wall and / or collar, so that excess powder swept from the workbench, wall and / or collar falls into the recovery tank.

[0051] A suction device and filter can be provided to aspirate, filter, and reuse excess powder. The powder recovered by the recovery device is aspirated, fed into the filter, and circulated to the processing area. The filter can filter out powder particles that are too large and / or already bound, and / or contaminated particles. For example, the filter can have a size of 120 μm so that only particles smaller than 120 μm can pass through the filter. Different filter sizes can be used depending on the powder and particle size used. The powder material thus cleaned can be supplied to a storage container and / or coating device for reuse. By recirculating the powder material in this way, raw material loss can be reduced. At the same time, it can be ensured that already bound powder particles are not reused or that contaminated powder particles are not used. Using already bound powder particles or contaminated particles can lead to inaccuracies or defects in 3D parts and adversely affect their stability or strength. Nevertheless, by using a suction device and filter, a high level of accuracy and quality in part manufacturing can be ensured.

[0052] The workbench can be tempered and maintained at a predetermined temperature. This helps to avoid stress on the parts, especially in the first layer. For example, when manufacturing metal parts, the workbench can be heated to a temperature between 100°C and 300°C, preferably between 150°C and 200°C. When manufacturing plastic parts in general, the workbench temperature can be lower, for example, between 40°C and 120°C, preferably between 60°C and 100°C. The temperature can be adjusted on a case-by-case basis depending on the material being used.

[0053] Preferably, an optical system, particularly a zoom lens, is provided to change the focus of the emitted light beam. The focus of the light beam can be easily adjusted to different distances to the processing area. Simultaneously, the energy input and the irradiation area can be changed according to the target focus setting.

[0054] A further aspect of the present invention provides an apparatus for additive manufacturing of parts by particularly selective melting or sintering, the apparatus comprising at least one movable part, preferably a processing head and / or a processing table and / or a wall and / or a scraper and / or a dispensing dispenser, and a drive device for moving the movable part. The apparatus is preferably characterized by being provided with at least one distance sensor for electro-optical distance measurement. The distance sensor is positioned on or on the top of the movable part 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 positioned on the other object and measure the distance to the movable part. The distance between the movable part and the other object can be measured and determined at any time.

[0055] Preferably, the distance sensor is stationary and measures the distance between the sensor and the movable part. The distance between the fixed point and the movable part can be measured and determined at any time. The movable part may include a reference object, and the distance sensor detects the reference object and measures the distance to the reference object. For example, a reflector, especially a prism reflector, can be used as the reference object. The distance sensor may be designed to rotate so that it can be aligned with the reference object.

[0056] Distance measurement can be performed by triangulation and / or by measuring phase shift and / or motion time. In distance measurement by phase measurement, a laser beam is emitted. The phase shift or modulation of the reflected laser beam, compared to the emitted beam, depends on the distance. By measuring this phase shift, it can be used to determine the distance traveled. Distance measurement by phase shift measurement provides high accuracy. In laser triangulation, a beam of light is focused on the object to be measured and observed by a camera next to a sensor, spatially resolved photodiode, or CCD line. As the distance between the object to be measured and the sensor changes, the angle at which the light point is observed also changes, and the position of the image on the receiver also changes. From this change in position, the distance from the laser projector to the object to be measured is calculated using an angle function. Distance measurement by triangulation is simple, cost-effective, and highly accurate. When measuring motion time, a pulsed or modulated beam of light is emitted. Motion time is the time it takes for the beam of light to travel from the light source to the reflector (usually a retroreflector) and back to the light source. By measuring this operating time, the distance between the light source and the object can be measured at the speed of light. For distance measurement, alternative or additional sensors capable of spatial measurement, such as sensors that can scan lines, surfaces, or planes, or stereo cameras for three-dimensional localization of one or more objects, can be used. Due to the wide recording range, the corresponding sensors do not need to be designed to rotate.

[0057] Instead of optical sensors, other sensors can be used, such as ultrasonic sensors or sensors that determine distance by the operating time of radio waves.

[0058] In an advantageous embodiment, a control and adjustment device is provided that is designed to move a movable part to a set position according to the measured distance between the distance sensor and the movable part. By using the distance sensor together with the control and adjustment system, a low-cost and particularly lightweight reciprocator can be used to move the movable part. The low-cost and lightweight reciprocator has low positioning accuracy but can move particularly quickly. The position of the movable part can be controlled according to the distance between the movable part and the distance sensor. As the movable part approaches the target position, the speed of movement of the movable part decreases. In this way, it is possible to ensure that the movable part reaches the target position accurately. The reciprocator can be simple, and above all lightweight and inexpensive, because accuracy of movement and positioning is ensured by distance measurement and control in a closed servo loop. As the controller of the servo loop, a proportional controller (so-called P controller), a proportional-integral controller (so-called PI controller), and / or a proportional-integral-derivative controller (so-called PID controller) can be used.

[0059] To determine the spatial position of a movable part, two, preferably three, distance sensors can be provided to measure the distance between the distance sensor and the movable part. If the movable part moves only in one plane, i.e., two dimensions, its position can be accurately determined by measuring the distance from two distance sensors. By measuring the distance between the movable part and three fixed distance sensors, the spatial position of the movable part can be accurately determined in three dimensions. Furthermore, if the movable part moves in only one direction, one sensor is sufficient for distance measurement.

[0060] In a preferred embodiment, four or more distance sensors and at least two movable parts are provided, and each movable part can be detected at any position by at least three distance sensors for distance measurement. As a result, one distance sensor can be used to measure the distance between itself and two movable parts. Depending on the position of the first movable part, the distance sensor may be obscured by this first movable part, making it impossible to measure the distance to the second movable part. In such a case, distance measurement can be performed via another distance sensor that has direct optical access to the second movable part. This allows the use of different or the same distance sensor for determining the position of each movable part by distance measurement.

[0061] Distance sensors can be fixedly positioned within the apparatus, for example, connected to the apparatus's base via a carrier. The distance sensors can determine the position of the powder bed surface by distance measurement, and then determine the position of a movable component, such as the processing head, by another distance measurement. The processing head can be moved to a set position, depending on the position of the powder bed, i.e., the height of the powder bed, in order to set the required distance between the processing head and the powder bed surface. In this case, the movement of one or more processing heads to their target positions can be carried out with the assistance of the control and adjustment devices described above. Alternatively, one or more distance sensors can be connected to the processing head or placed on the processing head to determine the distance between the processing head and the powder bed surface, and then the processing head can be moved to the required distance from the powder bed surface.

[0062] Furthermore, the position of one or more processing heads can be set as a function of the position of the movable wall, particularly the upper end and / or the horizontal plane. To determine the distance between the movable wall and the processing head, one or more distance sensors can be connected to the processing head and / or placed stationary within the device.

[0063] Instead of determining the position of one or more processing heads, the position of another component in the traverse or direction of movement, such as a carriage, can be determined and positioned relative to the movable wall or surface of the powder bed. For this purpose, one or more distance sensors can be directly connected to the traverse to measure the distance to the surface of the powder bed.

[0064] The scraper can also be positioned similarly relative to the surface of the powder bed or a movable wall. At least one distance sensor can be connected to the scraper for this purpose, or it can be stationary within the apparatus.

[0065] Furthermore, the dispensing dispenser can be positioned according to the location of the movable wall and the powder layer. For this purpose, the dispensing dispenser may have at least one distance sensor, or at least one distance sensor may be stationary within the device.

[0066] The movable wall can also be moved to a position, for example, one layer higher than the surface of the powder bed. For this purpose, it is advantageous to position a distance sensor stationary within the device.

[0067] Furthermore, the supply cylinder can be moved relative to the processing table. In the case of the type of apparatus described above, the processing table can also be moved in a controlled manner. For example, after a part layer is completed, the processing table can be lowered by a defined layer thickness to allow for the application of a new powder layer. In this way, the distance between the processing head and the surface of the powder layer can be kept constant for each part layer being manufactured. It is preferable that the distance sensor be stationary within the apparatus.

[0068] Furthermore, multiple components can be joined together and moved as a unit. For example, a scraper, having one or more processing heads and / or together with a dispensing dispenser, can be positioned in a controlled manner at the required vertical distance from the surface of the powder bed. The vertical distance between the scraper and the processing heads and / or dispensing dispensers remains constant.

[0069] For distance measurement, three distance sensors can be permanently assigned to each moving part. The same three distance sensors can be assigned to the same moving part for each distance measurement. However, it is also possible to reassign the distance sensors to parts for each distance measurement. Thus, each moving part can be assigned to partially or completely different distance sensors for each new distance measurement than for previous measurements.

[0070] A further aspect of the present invention provides an apparatus for additive manufacturing of a component by particularly selective melting or sintering, the apparatus comprising: a glass plate whose surface forms a support surface for powder; a processing area above the glass plate; a light source for generating a light beam; and a processing head disposed below the glass plate, the processing head being coupled to the light source by a beam guide such that the light beam is directed from the processing head through the glass plate onto the processing area, the processing head being movable so as to direct the light beam to different locations in the processing area. The apparatus is characterized by having a plurality of processing heads for guiding the light beam through the glass plate to the processing area, each processing head being arranged on a carriage movable along a traverse. [Effects of the Invention]

[0071] In the apparatus described above, the powder can be deposited onto the surface of a glass plate, for example, with the assistance of a coating dispenser. The glass plate forms a support surface for the powder. A scraper can be provided to smooth the powder layer. Next, a support can be placed on the powder layer. A beam of light can be irradiated from a processing head located below the glass plate, through the glass plate, onto the corresponding area of ​​powder. The powder can be selectively melted or sintered and bonded together to form a first component layer on the support. The formed component layer can then be lifted together with the support. For this purpose, a lifting device can be provided to assist in gripping and lifting the component or component layer vertically. Any powder remaining on the glass plate can be removed from the glass plate. The powder can then be reapplied to the glass plate. An already formed component layer can be placed on top of the applied powder. By re-irradiating the processing area with a beam of light, a new component layer can be formed and bonded to the first component layer. These steps can be repeated any number of times until the component is completely formed. The component is manufactured from top to bottom. This device configuration allows for material savings because powder can be deposited only in the areas where the component layer is formed. Therefore, it is not necessary to cover the entire glass plate with powder. The weight of the glass plate is significantly reduced because the component is held by a lifting device, and the glass plate only carries the powder bed for the newly formed component layer. The already formed component layer is freely accessible and not surrounded by powder. Therefore, the component can be further processed during manufacturing, for example, by cutting it.

[0072] The embodiments of the present invention described above can be combined as needed. The embodiments of the present invention described above are not limited to the combination of features of the present invention indicated by the selected paragraph format. [Brief explanation of the drawing]

[0073] Further features of the present invention are derived from the following description of the invention with reference to the drawings and from the drawings themselves. In this regard, all of the features described and / or illustrated, whether in themselves or in any combination, constitute the subject matter of the present invention, regardless of their summary relating to the claims or their interaction.

[0074] The present invention will be described in more detail below with reference to the drawings, which schematically show the following.

[0075] [Figure 1] This is a side cross-sectional view of the processing chamber of the equipment used for additive manufacturing of parts. [Figure 2] The supply cylinder and powder bed are shown in a top view, as are multiple processing heads that can be freely positioned on the powder bed. [Figure 3a] The diagram shows a swivel arm for positioning the processing head, with a beam guide formed from a light guide, which extends from the light source to the processing head. [Figure 3b] A side view shows a further swivel arm with a light source at its free end. [Figure 3c] A schematic side cross-sectional view shows a further swivel arm designed as a light guide, with the light guide extending from the light source to the swivel joint of the swivel arm, and a beam guide formed by reflector elements provided along the swivel arm. [Figure 3d] A further swivel arm with an excitation laser is shown, and the optical pump and resonator are spatially separated in the side view. [Figure 3e] A schematic lateral cross-sectional view shows a further swivel arm designed as a light guide, the light guide extending from the light source to the swivel arm, with its end away from the light source positioned parallel to the swivel arm and directed toward the free end of the swivel arm 18, and a reflector element for deflecting the light beam is provided at the free end of the swivel arm. [Figure 4] A side cross-sectional view shows a second embodiment of the processing chamber of an apparatus for additive manufacturing of parts. [Figure 5] A side view shows a swivel arm for positioning a processing head, which is equipped with a sensor for detecting the spatial position of the processing head. [Figure 6] The procedure for adjusting the spatial position of the processing head shown in Figure 5 is described below. [Figure 7] A processing table, comprising a glass plate and multiple processing heads that can be freely positioned below the glass plate, is shown in a side cross-sectional view. [Modes for carrying out the invention]

[0076] The following describes an example of an embodiment of an apparatus for additive manufacturing of parts (hereinafter simply referred to as "3D printer" 1). Such a 3D printer 1 has a processing chamber 2 that is closed on all sides, and a powder bed 3 and a supply cylinder 4 are arranged inside it (Figures 1 and 2). A supply piston 5 is located inside the supply cylinder 4 and can be raised or lowered vertically by a first piston / cylinder unit 6.

[0077] The powder bed 3 is similarly formed from a cylindrical body that is roughly rectangular when viewed from above, and a production piston 7, which is actuated by a second piston / cylinder unit 8, is mounted therein so as to be vertically displaceable. The powder bed forms a processing area in which 3D parts 31 can be manufactured.

[0078] The supply cylinder 4 and the powder bed 3 are located within the processing chamber 2. The powder bed 3 is located adjacent to the supply cylinder 4. A scraper 9 is provided, which can move in the direction of movement 10 (Figure 1) to spread the powder 11 stored in the supply cylinder 4 onto the powder bed 3. In this way, the scraper 9 transfers the surface layer of powder from the supply cylinder 4 to the surface in the powder bed 3. By gradually raising the supply piston 5 and gradually lowering the production piston 7, it is possible to maintain the surface of the powder 11 in the powder bed 3 and the supply cylinder 4 at approximately the same level.

[0079] A moving device 12 for moving a number of processing heads 13 is provided in the area above the powder bed 3.

[0080] The moving device 12 includes a plurality of traverses 14 extending across the powder bed 3. The traverses 14 are arranged parallel to each other. In this embodiment, three traverses 14 are provided (Figures 1 and 2). The central traverse 14 is positioned slightly higher than the two outer traverses 14.

[0081] Each traverse 14 has a substantially rectangular cross-section and each has a rail profile 16 projecting from a vertical longitudinal surface 15 that extends along the entire length of the traverse 14 (Figures 3a-3e). Two carriages 17 are attached to the rail profiles 16 of each traverse 14 so that they can move along the longitudinal direction of the traverse 14. The carriages 17 can be automatically moved along each traverse 14 by a drive mechanism. The drive mechanism may consist of a drive belt driven by an external motor coupled to each carriage 17. However, a drive mechanism such as a motor-driven drive wheel can also be provided on the carriage 17 itself. In principle, it is also possible to drive the carriages with a linear motor, in which case corresponding drive and drive-off means must be provided on the carriage 17 and traverse 14.

[0082] The swivel arm 18 is positioned on the carriage 17 by a swivel joint 19. The swivel arm 18 is rotatably mounted by the swivel joint 19 around a vertical swivel axis 20. A stepping motor (not shown) is provided on the carriage 17 to rotate the swivel arm 18 around the swivel axis 20. At the end of the swivel arm 18 away from the swivel axis 20 is a processing head 13, which in the embodiment shown in Figure 3a is formed by the end 22 of a light guide 21 and an optical lens 23 positioned at the end 22 of the light guide 21. The processing head 13 is positioned so that the beam of light 24 guided into the light guide is emitted vertically downward.

[0083] The light guide is formed from a flexible optical fiber. The optical fiber may be, for example, a glass fiber or an optical polymer fiber.

[0084] The stepping motor and slewing joint 19 are positioned very close to the slewing axis. This means that the intrinsic mass of the parts rotatable with the slewing arm 18 is concentrated around the slewing axis 20. Because the slewing arm 18 itself is relatively lightweight, its rotational moment of inertia is small, allowing the slewing arm 18 to rotate around the slewing axis 20 quickly and with high precision.

[0085] The light guide 21 leads to a light source 25 located a short distance from the swivel arm 18. The light source 25 is preferably a laser, particularly a CO2 laser, an ND:YAG laser, or a fiber laser. The light source 25 may also be a semiconductor laser or a light-emitting diode (LED), particularly a superluminescent light-emitting diode.

[0086] Alternatively, the array of light sources 25 may be configured so that each processing head 13 is equipped with a light source 25.

[0087] Further embodiments of the slewing arm are described below, which, unless otherwise specified, are designed in exactly the same way as the embodiments described above with reference to Figure 3a.

[0088] In the alternative embodiment of the swivel arm 18 (Figure 3b), the light source 25, which is integrated with the optical lens 23, is positioned directly at the end of the swivel arm 18, away from the swivel axis 20, so that the light beam 24 can be emitted vertically downward. Otherwise, the swivel arm 18 is configured in exactly the same way as the embodiment described above in Figure 3a.

[0089] In a further embodiment (Figure 3c), a beam guide is formed from the light source 25 to the carriage 17 by a light guide 26 and along the swivel arm 18 by reflector elements 27 and 28. In this embodiment, the reflector elements 27 and 28 are each formed as mirrors. However, these can also be represented by other optical elements that deflect the light beam, such as prisms.

[0090] The swivel arm 18 is designed as a hollow plastic pipe, and can be formed from fiber-reinforced plastic in particular. Such a plastic pipe is very lightweight and highly rigid.

[0091] The swivel joint 19 has a vertically extending through-opening or through-hole 29. The end of the light guide 26, away from the light source 25, is positioned adjacent to the through-hole 29 above, together with the coupling lens 30, so that the light beam generated by the light source 25 passes through the light guide 26 and is coupled into the through-hole 29 of the swivel joint 19. The first reflector element 27 is positioned below the through-hole 29 and deflects the light beam 24 so that it is directed toward the free end of the swivel arm 18. The second reflector element 28, which deflects the light beam 24 vertically downward, is positioned at the free end of the swivel arm 18, away from the swivel axis 20. Optionally, an optical lens 30 can be provided in the optical path between the end of the light guide 26, positioned adjacent to the swivel joint 19, and the second reflector element 28 to collimate the light beam. Alternatively, instead of the optical lens 30, a camera lens with adjustable collimation of the light beam can be provided.

[0092] The first and / or second reflector elements 27, 28 can be shaped, for example, as a parabolic mirror or a free-form mirror, to collimate the reflected light. This eliminates the need to place an optical lens in the optical path, or allows for the placement of an optical lens with low refractive power in the optical path.

[0093] As the processing head 13 is moved by the swivel arm 18, the light guide 26 simply moves along the traverse 14 with its end positioned on the carriage 17. The swivel arm 18 can perform rotational motion that does not affect the position of the light guide 26. This allows the swivel arm 18 to perform one or more full rotations without affecting the function of the light guide 26, as the light guide 26 is not caught during such rotational motion of the swivel arm 18.

[0094] This arrangement allows multiple processing heads 13 to be mounted by swivel arms on carriages 17 that can move along the traverse 14, thereby ensuring that the individual light guides 26 do not become entangled with each other. This makes it easy to manufacture a 3D printer 1 having at least 8, preferably at least 12, and especially at least 16 processing heads, all of which can supply light beams 24 simultaneously or nearly simultaneously.

[0095] The light source 25 can generate a light beam in continuous (CW) or pulsed (PW) operation. In the case of a pulsed light source 25 with high light intensity, it is also advantageous to assign the light source 25 to multiple processing heads 13. In this case, by placing a multiplexer between the light source 25 and each processing head 13, the multiplexer can be used to uniquely direct the light beam generated by the light source to one of the multiple processing heads 13. Changes between individual processing heads 13 occur very rapidly compared to melting or sintering processes, and the individual processing heads 13 coupled to it can be considered to act on the light beam 24 almost simultaneously.

[0096] A further embodiment of the swivel arm (Figure 3d) includes an excitation laser as a light source, comprising an optical pump 32 and a resonator 33 connected to each other via a light guide 34. The resonator is preferably made of a solid active medium and is excited or pumped by excitation light 35 emitted by the optical pump 32.

[0097] The resonator 23, along with the optical lens 23, is positioned directly at the end of the swivel arm 18, away from the swivel axis 20, so that the light beam 24 can be emitted vertically downward. The optical pump 32 is positioned on the carriage 17 so as not to be involved in the swivel of the swivel arm. The optical pump 32 typically comprises one or more semiconductor lasers and a heat sink with cooling fins. The optical pump is much heavier than the resonator 33 and optical lens 23. Since only the resonator 33 and optical lens 23 are moved and the optical pump 32 is not, the rotational moment of inertia of the swivel arm 18 is small.

[0098] In this embodiment, the optical pump 32 is located on the carriage 17. However, the optical pump 32 can also be located independently of or at a distance from the carriage 17.

[0099] This embodiment can also be modified, as shown in Figure 3c, to include a beam guide having a reflector element instead of the light guide 34. The light guide 34 may be completely omitted or only guided to the carriage 17 if the optical pump is located far from the carriage 17.

[0100] It is preferable to use an ND:YAG laser as the pump laser and one or more laser diodes with a wavelength of 808 nm as the optical pump. However, another laser, such as a Yb:YAG laser, can also be used.

[0101] According to a further embodiment (Figure 3e), a beam guide is formed by a light guide 26 from the light source 25 to the swivel arm 17. The light guide 26 is guided from the light source 25 to the swivel arm 18, with its end positioned in the region of the carriage 17, below the swivel arm 18 and away from the light source 25. The light guide 26 is guided along the swivel arm in the region of the carriage 17 and is connected to the swivel arm 18 such that its end, away from the light source 25, faces the free end of the swivel arm 18. A reflector element 28 is positioned at the free end of the swivel arm 18, which is designed as a mirror. However, the reflector element 28 can also be represented by other optical elements that deflect the light beam 24, such as a prism.

[0102] The light beam 24 emitted by the light source 25 is transmitted by the light guide 26 such that the light beam 24 is deflected along the swivel arm 18 toward the reflector element 28, preferably parallel to the swivel arm, and is emitted from its end away from the light source 25. The second reflector element 28 is positioned at the free end of the swivel arm 18 to deflect the light beam 24 downward onto the processing area. Optionally, an optical lens 30 can be provided in the optical path between the end of the light guide 26 and the reflector element 28 to collimate the light beam 24. Instead of the optical lens 30, a camera lens can be provided to allow for variations in the degree of collimation of the light beam 24, and / or the reflector element 28 can be formed with appropriate curvature.

[0103] When the processing head 13 is moved by the swivel arm 18, only the end of the light guide 26 away from the light source 25 is carried along with it. In this embodiment, since only a small load needs to be collected, the swivel arm 18 can be made particularly lightweight. A well-designed swivel arm 18 has a small moment of rotational inertia, so it can be quickly swung to any rotational position. Also, because the weight of the swivel arm 18 is small, the carriage 17 can also be moved very quickly.

[0104] This arrangement of 18 allows for the provision of multiple processing heads 13, each by a pivoting arm 18 on a carriage 17 that is movable along the traverse 14, thereby ensuring that the individual light guides 26 do not become entangled with one another. This makes it easy to fabricate a 3D printer 1 having at least eight, preferably at least twelve, and especially at least sixteen processing heads 13, all of which can supply light beams 24 simultaneously or nearly simultaneously.

[0105] In this embodiment, the traverses 14 and, consequently, the slewing arms 18 attached to them are positioned at different levels (Figure 1: the central traverse is higher than the lateral traverses), so that the slewing arms 18 positioned on the central traverse 14 do not collide with the slewing arms 18 positioned on the outer traverses 14. Furthermore, if all traverses are arranged at the same height, the levels of the slewing arms 18 can be designed to be different. This can be achieved, for example, by attaching the slewing joints 19 to the individual carriages 17 at different heights.

[0106] In the embodiments described above, the traverse 14 is stationary. However, within the scope of the present invention, it is also possible to move the traverse horizontally and laterally relative to its longitudinal direction. However, such embodiments of the moving device 12 require more complex control to prevent collisions between the individual slewing arms 18. Therefore, in principle, an arrangement with a stationary traverse 14 is preferred. Such embodiments of the moving device 12 can be easily expanded for the 3D printer, for example, by adding an additional carriage on an existing traverse, or by attaching one or more additional traverses to increase the production speed.

[0107] In the embodiments described above, the swivel arm 18 is not adjustable in the vertical direction. However, within the scope of the present invention, it is possible to either provide a device on the carriage 17 to adjust the vertical position of the swivel arm 18, or to make the entire traverse 14 and / or moving device 12 adjustable in the vertical position. This is particularly useful to provide sufficient space for the scraper 9 to move between the powder bed 3 and the swivel arm 18 when the powder bed 3 is being scraped by the scraper 9, and after the scraper 9 has left the area of ​​the powder bed 3 again, the swivel arm 18 can be lowered to bring it as close as possible to the surface of the powder located in the powder bed 3 together with the processing head 13.

[0108] The light sources 25 for each processing head 13 can be designed identically, and each can generate a beam of light having the same intensity and frequency or frequency range. However, within the scope of the present invention, it is also possible to provide different light sources for different processing heads, which emit light at different frequencies or frequency ranges and / or different intensities. It is also possible to provide light sources whose wavelength can be tuned over a specific range. Such frequency-tunable lasers are known and typically have a semiconductor amplifier.

[0109] An advantage of the present invention is that different locations of the powder 11 within the powder bed 3 can be simultaneously exposed to light, and therefore heat, by multiple processing heads 13, and simultaneously melted or sintered. This parallelizes the manufacturing process, significantly improving the manufacturing speed compared to conventional 3D printers. Therefore, 3D parts 31 (Figure 1) can be manufactured at very high speed.

[0110] Because the processing head 13 can be positioned very precisely on the powder bed 3, high-precision 3D parts can be manufactured.

[0111] The moving device 12 for the processing head 13 has a very simple design and can be manufactured far more cost-effectively compared to 3D printers with similar performance.

[0112] A first version of the second embodiment is described below. Similar to the first embodiment, the second embodiment comprises a processing chamber 2, a powder bed 3, a scraper 9, and at least one processing head 13. Identical parts in the second embodiment are denoted by the same reference numerals as in the first embodiment. The above description applies to the same parts unless otherwise stated below. The processing chamber 2 may be equipped with a device to supply an inert gas atmosphere to prevent oxidation of the powder 11 during part manufacturing.

[0113] A processing table 36 having a table plate 37 is provided in the processing chamber 2. The processing table 36 includes tempering channels 38 for tempering the table plate 37, also called a support surface, to a desired temperature. By tempering the table plate 38, stress in the component, particularly in the first component layer, can be reduced, completely relieved, or prevented.

[0114] Within the processing chamber 2, the processing head 13 is mounted on a mobile device 12 (not shown in Figure 4), similar to the first embodiment, to direct the light beam 24 onto the processing table 36. However, the processing head 13 can also be stationary, and the light beam emitted by the processing head can be directed to any point in the powder bed 3, for example, by a deflection device having two movable mirrors.

[0115] Instead of a single processing head 13, a mobile device 12 having multiple processing heads 13 can be provided, as shown in Figures 1 to 3d.

[0116] A dispensing dispenser 39 is provided within the processing chamber, and this dispenser comprises a storage chamber 40 for the powder 11 and a closable dispensing opening 41 from which the powder 11 can exit the storage chamber 40 to be dispensed onto the processing table 36. The dispensing dispenser 39 has a scraper 9 for smoothing the powder 11 that has been dispensed onto the powder bed 3.

[0117] The processing table 36 is surrounded horizontally by walls 42. The walls 42 surround the tabletop 37 of the processing table 36 with almost no gaps.

[0118] The wall 42 is connected to the base 44 of the 3D printer 1 via a plurality of lifting cylinders 43. The lifting cylinders 43 can adjust the vertical height of the wall 42 relative to the processing table 36. Thus, the wall 42 can protrude slightly upward from the side of the processing table 36, thereby partitioning the cavity that forms the powder bed 3. The processing table 36 can be connected to the base 44 by dampers to reduce or prevent the transmission of shocks and vibrations to the processing table 36.

[0119] The dispensing dispenser 39 is coupled to a moving mechanism (not shown), which allows the dispensing dispenser 39 to move horizontally across the processing table 36, and therefore parallel to the table plate 37 of the processing table 36. The moving mechanism of the dispensing dispenser 39 is coupled to the wall 42 such that the moving mechanism moves up and down together with the wall 42. As a result, the lower edge 45 of the scraper 9 is always at the height of the upper edge 46 of the wall 42.

[0120] The height adjustment of the wall 42 can be coordinated with other components within the processing chamber. Therefore, the processing head 13 can also be moved together with the wall 42. The vertical distance between the processing table 36 and the processing head 13, or the vertical distance between the processing head 13 and the wall 42, remains constant for each part layer being manufactured. Therefore, the light beam 24 does not need to be refocused at the manufacturing height before manufacturing each part layer. This allows for accelerated process control of part manufacturing.

[0121] The wall 42 may be provided with a collar 47 projecting horizontally outward from its upper edge, thereby preventing powder from falling onto the foundation in unintended areas. The collar 47 may be provided on only one side of the powder floor 3, or it may be formed on multiple sides or circumferentially.

[0122] For example, to recover excess powder 11 swept from the processing table 36 or collar 47 by the scraper 9, a recovery device designed as a recovery tank 48 is positioned around the processing table 36 or collar 47. The recovery tank 48 is connected to a suction device 49 that supplies the recovered powder 11 to a filter 50. Particles larger than a certain particle size, for example, particles larger than 120 μm, are retained in the filter 50. Thus, the particles that are filtered can be, for example, dirt particles or powder particles that are already bound together. The powder material filtered through the filter 50 is then supplied to the application dispenser 39 via the supply line 51 and reused. In this way, a recirculation loop is formed through which excess powder 11 can be reused, thereby achieving material savings.

[0123] In this embodiment, since there is no need to move the processing table 36, the processing table 36 can be designed to be particularly simple, resulting in high cost-effectiveness. In additive manufacturing of parts, the processing table 36 needs to be designed to withstand high loads due to the high material density. For example, if the processing table has a support surface of 1.5m x 1m and a stroke of 0.5m, then 0.75m 3 This results in a working volume. When this working volume is filled with aluminum powder, the weight of the contents is approximately 2 tons. In the case of iron powder, it is approximately 6 tons. The wall 42 and other movable parts (applied dispenser 39, scraper 9, processing head 13, etc.) as needed are significantly lighter than the processing table 36, which has a large working volume. Therefore, these parts can be processed with a drive unit of significantly smaller dimensions, reducing both acquisition and operating costs. At the same time, the structure of the 3D printer 1 is also simplified.

[0124] Figure 4 shows the processing chamber 2 at the start of additive manufacturing of a part. To apply powder 11 to the processing table 36, the application dispenser 39 moves in the direction 10 across the entire processing table 36. The applied powder 11 is smoothed by the scraper 9. The first part layer can then be formed by the light beam 24. After the first part layer is formed, the wall 42 is moved upward by the height of the first part layer or powder layer. The application dispenser 39 is moved upward by the same height coupled to the wall 42. The above steps are then repeated until the part is completely manufactured. The wall 42, together with the processing table 36, forms a powder bed 3 with increasing height.

[0125] The wall 42 can be moved according to the thickness of the next part layer to be formed. Each part layer can have a different thickness. For example, if high molding precision is not required in a corresponding part area, individual part layers can be made thicker than others during production. This accelerates part production in individual part areas, resulting in very fast overall production. On the other hand, if high molding precision is required in an individual part area, the manufactured part layers can be made thinner. In this way, parts can be manufactured particularly quickly according to the dimensional precision required in each area.

[0126] According to a second modification of the second embodiment, the moving device 12 for the processing head 13 can be mechanically detached from the wall 42 so that they can move independently of each other (Figure 5). Each processing head 13 is connected to the traverse 14 via a swivel arm 18, a swivel joint 19, and a carriage 17. Unlike the first embodiment, a vertical moving device is provided on the carriage 17, and the processing heads are positioned to move vertically. In Figure 5, only one processing head 13 is shown for the sake of visual simplification.

[0127] The processing head 13 is equipped with an optical lens 23, which focuses the beam of light 24 irradiated by it onto the surface of the powder bed. Three distance sensors 52 are stationary within the processing chamber 2. The distance sensors 52 are designed to perform 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 the beam of light, such as a reflector, in particular a prism reflector, is placed on the processing head 13.

[0128] The distance sensor 52 is stationary within the processing chamber 2 but is pivotably positioned so that each light beam 54 emitted by the distance sensor 52 can follow the reference element 53. The distance sensor 52 is connected to a control and adjustment device 55. The spatial position of the processing head 13 can be accurately determined from three measured distances between the processing head 13 and the three distance sensors 52. With the assistance of the control and adjustment device 55, the processing head 13 can be precisely moved to a desired position in three-dimensional space. The positioning of the processing head 13 is controlled by distance measurement.

[0129] This allows the movement of the processing head 13 to be separated from the movement of the wall 42, and yet the emitted light beam 24 can be precisely focused onto the surface of the powder bed.

[0130] Preferably, one or more reference elements 53 are provided on the wall 42, particularly its upper edge, and can be scanned by a distance sensor to determine the height of the wall 42. This allows the relative position of the processing head 13 and the wall 42 to be detected.

[0131] Instead of detecting the height of the wall 42, the height of the powder bed 3 can also be scanned with an appropriate sensor. In this way, the processing head 13 can be directly aligned with the height of the powder bed 3.

[0132] The drive that moves the carriage 17 and the swivel joint 19 is controlled by the control and adjustment device 55 according to the actual position of the processing head 13. Therefore, the processing head 13 can be moved more slowly as it approaches the target position. In this way, even with an inexpensive and not-so-accurate moving device 12, the processing head 13 can be accurately moved to the target position, thereby the positional accuracy is determined solely by measuring the distance with the distance sensor 52. Since the distance sensor 52 is inexpensive, and a less expensive moving device 12 or a less expensive drive device can be used, the overall cost of the 3D printer 1 can be reduced.

[0133] The setup shown in Figure 5 for controlling and adjusting the processing head 13 can also be used, with the assistance of a servo loop, to precisely position other parts such as the scraper 9, the dispensing dispenser 39, the wall 42, or any other moving parts.

[0134] In a second embodiment, an optical distance sensor 52 is used to measure the distance between a reference element 53 and the distance sensor 52. Such distance sensors 52 are inexpensive and have very high resolution. They can use triangulation to detect the distance to the reference element 53. In triangulation, an optical beam of light, such as a laser beam, is focused on the object to be measured and observed by a camera, spatially resolved photodiode, or CCD line placed next to the distance sensor 52. As the distance between the object to be measured and the sensor changes, the angle at which the light point is observed also changes, and the position of the image on the receiver also changes. From this change in position, the distance of the object from the laser projector is calculated using an angle function. Distance measurement by triangulation is very simple and inexpensive. If the requirement for accuracy is low, the radiation from a light-emitting diode can also be used as a ray.

[0135] Distance can also be measured by measuring the phase position. When measuring the phase position, a beam of light 54, such as a laser beam, is emitted. The phase shift of the reflected laser beam compared to the emitted beam is distance-independent. This phase shift can be measured and used to determine the distance traveled. Distance measurement by measuring the phase difference is highly accurate.

[0136] Distance measurement using motion time involves irradiating with short pulses of light, a constant beam of light, or modulated light. The motion time of a pulse is the time required for the beam of light to move from the light source to the reflector and back to the light source. By measuring this motion time, the distance between the light source and the object can be determined at the speed of light.

[0137] Furthermore, sensors capable of scanning lines, surfaces, or planes, such as stereo cameras that perform three-dimensional positioning of one or more objects, can also be used for distance measurement. Due to their wide recording range, the corresponding sensors do not need to be redesigned to allow for rotation.

[0138] The distance sensor 52 mentioned above is manufactured and sold by, for example, Micro-Epsilon.

[0139] Instead of optical sensors, other sensors can be used, such as ultrasonic sensors or sensors that determine distance by the operating time of radio waves.

[0140] Regardless of the type of sensor, the servo loop offers the advantage of being able to set the position of the processing head with great precision. This can also be used to determine the position of a processing head that can only move within a single plane, as in the first embodiment.

[0141] For accurate positioning, the actual position of a movable part, such as the processing head 13, can be detected after startup (Figure 6). For this purpose, the distance between the processing head 13 and each distance sensor 52 can be measured. The actual position is detected by measuring the distance with the assistance of the distance sensors 52 as shown in Figure 5. From the three distance measurements, the actual position of the processing head can be determined in a simple manner. If the actual position matches the target position, no further action is required, and production of parts can continue.

[0142] The position of a movable part, such as the processing head 13, can be determined absolutely in space. However, the position of a movable part can also be determined relative to another part. In the latter case, the distance between the two parts is determined.

[0143] The actual position of the movable parts can be controlled individually and continuously with respect to each spatial direction or axis until the target position is reached. However, it is also possible to control the position of the movable parts simultaneously in all three spatial directions or with respect to all axes.

[0144] The distance sensor 52 can be stationary and positioned within the processing chamber 2 of the 3D printer 1. For example, the distance sensor 52 can be connected to the base 44 of the 3D printer 1 via a carrier. The distance sensor 52 can determine the position of the surface of the powder bed 3 by distance measurement, and then determine the position of a movable part, such as the processing head 13, by another distance measurement. The processing head 13 can be moved to a target position depending on the position of the powder bed 3, i.e., the height of the powder bed 3, in order to set the required distance between the processing head 13 and the surface of the powder bed 3. In this case, the movement of one or more processing heads 13 to the target position can be performed with the assistance of the control and adjustment device 55 described above. Alternatively, by connecting one or more distance sensors 52 to the processing head 13 or placing them on the processing head 13, the distance between the processing head 13 and the powder bed surface can be determined directly, and then the processing head 13 can be moved to the required distance from the surface of the powder bed 3.

[0145] If the actual position does not correspond to the target position, the position of the processing head 13 is then corrected. For this purpose, the drive can be started and the moving speed of the processing head 13 can be set according to 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 moving speed can be selected. After a specified unit time and / or a defined distance of movement, the actual position can be detected again and corrected as necessary. It is also possible to continuously record the actual position. In this way, a closed servo loop can be created. This servo loop allows the processing head 13 to be accurately moved to the target position using a simple, inexpensive, and not very accurate moving device 12. The positioning accuracy is determined solely by distance measurement by the distance sensor 52.

[0146] Furthermore, the position of the processing head 13 can also be set as a function of the position of the movable wall 42, particularly the upper end and / or the horizontal plane. For this purpose, at least one distance sensor 52 can be connected to the processing head 13 or placed stationary within the 3D printer 1.

[0147] Instead of determining the position of one or more processing heads 13, the position of a traverse 14 or another component in the direction of movement 12, such as a carriage 17, can also be determined and positioned relative to the movable wall 42 or the surface of the powder bed 3. For this purpose, the traverse 14 is equipped with one or more distance sensors 52 that can measure the distance to the surface of the powder bed 3.

[0148] Similarly, the scraper 9 can be positioned relative to the powder bed surface or the movable wall 42. Then, one or more distance sensors 52 can be connected to the scraper 9 and / or stationary within the processing chamber 2.

[0149] Furthermore, the dispensing dispenser 39 can be positioned according to the position of the movable wall 42 or the surface of the powder bed 3. For this purpose, the dispensing dispenser 39 is equipped with at least one distance sensor 52, and / or at least one distance sensor 52 can be stationarily positioned in the processing chamber 2 of the 3D printer 1.

[0150] The movable wall 42 can also be moved to a position higher than the surface of the powder bed 3, for example, by a layer thickness above the powder bed 3. For this purpose, it is advantageous for the distance sensor 52 to be stationary within the processing chamber 2 and to determine the distance between the movable wall 42 and the surface of the powder bed 3.

[0151] Furthermore, the supply cylinder 4 can also be moved relative to the processing table. In known 3D printers 1, the processing table 36, designed as the production piston 7, can also be moved in a controlled manner. For example, after a part layer is completed, the production piston can be lowered by a defined layer thickness to allow a new powder layer to be applied. The distance sensor 52 is then preferably stationary within the processing chamber 2 of the 3D printer 1.

[0152] Multiple movable parts can be combined and moved together. For example, the scraper 9, having one or more processing heads 13 and / or together with the dispensing dispenser 39, can be positioned in a controlled manner at a required vertical distance from the surface of the powder bed 3. In this case, the vertical distance between the scraper 9 and the processing heads 13 and / or dispensing dispenser 39 is always the same.

[0153] Further modifications of the third embodiment are described below. The same parts in the third embodiment are denoted by the same reference numerals as in the first and second embodiments. Unless otherwise specified, the following description applies to the same parts.

[0154] A glass plate 56 is horizontally positioned inside the processing chamber 2 as the table plate 37 of the processing table 36. Below the glass plate 56, a moving device 12 is provided for moving a number of processing heads 13.

[0155] The moving device 12 includes three traverses 14 extending below the glass plate 56. The traverses 14 are arranged parallel to each other. In this embodiment, the central traverse 14 is positioned slightly lower than the two outer traverses 14.

[0156] As illustrated in Figures 1 and 2, the mobile device 12 comprises two carriages 17 on each traverse 14, each having a slewing arm 18. At least one processing head 13 is positioned on each slewing arm 18. The slewing arms 18 can be designed as shown in Figures 3a to 3d.

[0157] A support 57 is positioned above the glass plate in the processing chamber 2, and parts are manufactured below it 58. The first part layer is formed below 58 and connectable to the support 57. The support is movable or adjustable in a vertical direction of movement 59 together with the parts 31. For this purpose, a lifting device 60 may be provided for gripping and lifting the parts 31.

[0158] To additively manufacture the 3D part 31, a coating dispenser 39 (not shown in Figure 6) can be used to deposit the powder 11 only over the entire surface of the glass plate 56. The glass plate serves as a support surface for the powder 11. The powder is smoothed by a scraper 9 (not shown in Figure 6), thereby forming a powder layer 61. A support 57 is then placed on top of the powder 11. The powder 11 is then selectively melted or sintered with the help of a beam of light 24 irradiated from a processing head 13, joining together to form a part layer. The part layer can then be joined to the support. Next, the part layer is lifted together with the support 57. A lifting device 60 may be used to assist in gripping and lifting the part layer. Unused powder 11 can then be removed from the glass plate 56 to prevent individual powder particles that are joined together from being used to manufacture the next part layer. The coating dispenser 39 can then deposit the powder 11 onto the glass plate again, forming a new powder layer 61. The part is then deposited on top of the new powder layer 61. The powder material is melted or sintered to form a new part layer that is simultaneously bonded to the previous part layer. The above steps are repeated until part 31 is completely manufactured. Part 31 is thus manufactured from top to bottom. [Explanation of Symbols]

[0159] 1 3D printer 2 Processing Chamber 3 powder bed 4. Supply Cylinder 5. Supply piston 6 Piston / Cylinder Unit 7. Manufacturing Piston 8 Piston / Cylinder Unit 9. Scraper 10 Direction of movement 11 powder 12 Mobile device 13 Processing heads 14. Traverse 15 Longitudinal surface 16 Rail Profiles 17 Carriage 18. Swivel Arm 19. Swivel joint 20 Swivel axis 21 Light Guide 22 End 23 Optical Lenses 24 Light beams 25 light source 26 Light Guide 27 Reflector elements 28 Reflector elements 29 Through hole 30 Optical Lenses 31 3D parts 32 Optical Pumps 33 Resonator 34 Light Guide 35 Excitation light 36 Processing Table 37 Tabletop 38 Tempering Channels 39. Dispenser 40 Storage Chambers 41 Application opening 42 Wall 43 Lifting Cylinder 44 Basics 45 Bottom end 46 Edge 47 Colors 48 Recovery tank 49 Aspirator 50 filters 51 Supply Line 52 Distance Sensor 53 Criteria 54 beams 55 Control and Regulators 56 Glass plate 57 Support 58 Lower side 59 Direction of movement 60 Lifting device 61 Powder layer

Claims

1. An apparatus for carrying out additive manufacturing of parts by particularly selective melting or sintering, A light source (25) for generating a beam of light (24), A processing head (13) wherein the light beam (24) is coupled to the light source (25) by a beam guide so as to be guided to the processing head (13), or the light source (25) is directly positioned on the processing head (13) so as to be guided from the processing head (13) onto the processing area, Equipped with, The processing head (13) is movably mounted so as to be able to direct the light beam (24) to different positions in the processing area. Multiple processing heads (13) are provided to direct the optical beams (24) towards the processing area, The processing heads (13) are each positioned on carriages (17) that are movable along the traverse (14), The processing head (13) is formed as a straight cantilever beam, is made of plastic, and is positioned on one of the carriages (17) by a swivel arm (18) that can swivel only around a vertical pivot axis (20). The apparatus wherein at least two carriages (17) are independently and movably mounted on the traverse (14), and the processing head (13) is positioned on each carriage (17).

2. The apparatus according to claim 1, characterized in that the swivel arm is formed to have a length of at least 5 cm.

3. The apparatus according to claim 1 or 2, characterized in that the beam guides for each of the light beam beams (24) are formed by reflector elements (27, 28) at least along the swivel arm (18).

4. The apparatus according to any one of claims 1 to 3, characterized in that the swivel arm (18) is made of fiber-reinforced plastic, and / or reflector elements (28) are provided at each end away from the swivel axis (20) in order to direct each of the light beams (24) onto the processing area.

5. The apparatus according to any one of claims 1 to 4, characterized in that one of the light sources (25), or one of the resonators (33) of a laser functioning as a light source (25), is positioned at each of the free ends of the swivel arm (18) away from the rotation axis (20).

6. The apparatus according to any one of claims 1 to 5, characterized in that a plurality of beam guides are provided and at least partially formed as light guides (21, 26).

7. The apparatus according to any one of claims 1 to 6, characterized in that a plurality of traverses (14) are provided, which are parallel to each other and arranged on a single plane.

8. The apparatus according to claim 7, characterized in that the traverse (14) is positioned in a stationary state.

9. The apparatus according to any one of claims 1 to 8, characterized in that a plurality of light sources (25), in particular arrays of light-emitting diodes and / or semiconductor lasers, are provided, and each light source (25) is assigned to one or more processing heads (13).

10. The apparatus according to any one of claims 1 to 9, characterized in that a multiplexer is provided for distributing one of the light beams of the light source (25) to different beam guides, and each of the beam guides is connected to one of the processing heads (13).

11. The apparatus according to any one of claims 1 to 10, characterized in that a control device is provided which is designed to move a plurality of processing heads (13) simultaneously and / or to apply a beam of light (24) simultaneously.

12. The apparatus according to any one of claims 1 to 11, characterized in that a powder bed (3) forming the processing area is provided.

13. A glass plate (56) whose surface forms a support surface for powder (11), a processing area on the glass plate (56), a light source (25) for generating a light beam beam (24), and a processing head (13) disposed below the glass plate (56), wherein the light source (25) is coupled to the processing head (13) by a beam guide so that the light beam beam (24) is guided to the processing head (13), or the light source (25) is connected to the processing head (13) so that the light beam beam (24) is guided from the processing head (13) through the glass plate onto the processing area. The apparatus according to any one of claims 1 to 12, further comprising: (13) a processing head (13) directly positioned on the processing area, wherein the processing head (13) is movably mounted so as to be able to direct the light beam (24) to different positions in the processing area, a plurality of processing heads (13) are provided to direct the light beam (24) to the processing area via the glass plate (53), and each processing head (13) is positioned on a carriage (17) that is movable along the traverse (14).

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