Patent Publication Number: US-2005116391-A1

Title: Apparatus and process for producing a three-dimensional shaped body

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
      Not applicable.  
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not applicable.  
     BACKGROUND OF THE INVENTION  
     FIELD OF THE INVENTION  
      The invention relates to an apparatus and a process for producing a three-dimensional shaped body which is consolidated by means of electromagnetic radiation or particle radiation, at locations corresponding to the respective cross section of the shaped body, having a beam source for generating a beam and a beam-deflection device for deflecting the beam onto the layer which is to be consolidated, having a carrier in a build-up chamber, arranged in a process chamber, for receiving the shaped body which is to be formed.  
     TECHNICAL FIELD  
      The present invention deals with additive manufacturing processes in which complex, three-dimensional components are built up in layers from material powders. The application areas for the invention include, in addition to rapid prototyping and the related disciplines of rapid tooling and rapid manufacturing, in particular the production of series tools and functional parts. These include, for example, injection moulds with cooling passages close to the surface and also individual parts and small series of complex functional components for medical technology, mechanical engineering, aircraft and automotive construction.  
      The generative manufacturing processes which are of relevance to the present invention include laser melting, which is known, for example, from DE 196 49 865 C1, in the name of Fraunhofer-Gesellschaft, and laser sintering, which is known, for example, from U.S. Pat. No. 4,863,538, in the name of the University of Texas.  
      In the laser-melting process which is known from DE 196 49 865 C1, the components are produced from commercially available, single-component metallic material powders without binders or other additional components. For this purpose, the material powder is in each case applied as a thin layer to a building platform. This powder layer is locally fused using a laser beam in accordance with the desired component geometry. The energy of the laser beam is selected in such a way that the metallic material powder is completely fused over its entire layer thickness at the location of incidence of the laser beam. At the same time, a shielding gas atmosphere is maintained above the zone where the laser beam interacts with the metallic material powder, in order to avoid defects in the component which may be caused, for example, by oxidation. It is known to use an apparatus shown in  FIG. 1  of DE 196 49 865 C1 to carry out the process.  
      In the laser-sintering process which is known from U.S. Pat. No. 4,863,538, the components are produced from material powders which have been specially developed for laser sintering and which, in addition to the base material, contain one or more additional components. The different powder components differ in particular in terms of the melting point. In the case of laser sintering, the material powder is applied to a building platform as a thin layer. This powder layer is locally irradiated with a laser beam in accordance with the geometry data of the component. The low-melting components of the material powder are fused by the laser energy which is introduced, while others remain in the solid state. The layer is secured to the previous layer by means of the fused powder components, which produce a bond on solidification. After a layer has been built up, the building platform is lowered by the thickness of one layer, and a new powder layer is applied from a storage vessel.  
      EOS GmbH Electro Optical Systems offers laser-sintering installations for processing plastics EOSINT P 700 and for processing sand EOSINT S 750, which installations have a process chamber, two lasers and two scanning units. The aim of these installations is to rapidly build up components of large volume.  
      According to WO 02/36331, Concept Laser GmbH proposes, for the production of components of relatively large volume, an apparatus for sintering, removal of material and/or writing by means of electromagnetic, focussed radiation, in which a scanner is arranged on a scanner carrier which can be displaced by motor means, in the style of a compound slide, over the building platform.  
      This apparatus includes a laser-processing machine with exchangeable technology modules for sintering, removal of material and/or writing. A plurality of building spaces are provided in a machine housing. The scanner carrier executes a reciprocating movement between the building spaces, so that a plurality of building spaces can be covered in any desired order. By way of example, it is proposed to provide four building spaces in an arrangement which approximates to a square, in order for four components to be built up, or processed in some other way, simultaneously and in parallel in a single machine. For this purpose, it is necessary for the scanner carrier to move to and fro between the building spaces in order to allow this simultaneous production of a plurality of components in the building spaces of a machine.  
      This arrangement has the drawback that the accessibility to the individual building spaces in a machine housing is made more difficult by the scanner carrier which can be displaced by motor means in the style of a compound slide and extends transversely across the building spaces. Furthermore, the parallel mode of action in the individual building spaces means that it is only possible to remove a finished component and carry out the necessary conversion work for a new component when the shaped bodies which are to be built up in parallel with the finished component in the further building spaces have also been completed. This has an adverse effect on the economics of this apparatus, since the component with the longest build-up time determines the removal and conversion work. Furthermore, the influences which arise during the production process, such as for example temperature, sparks which fly when a shaped body is being built up, may have an adverse effect on the further working processes proceeding in parallel therewith, such as for example coating, cooling, etc.  
     SUMMARY OF THE INVENTION  
      Therefore, the invention is based on the object of providing an apparatus and a process for producing a three-dimensional shaped body in which the production time is shortened and the flexibility of production and the quality of the shaped bodies are increased.  
      This object is achieved by an apparatus in that at least two process chambers are provided, in that each process chamber is hermetically locked off and is in each case designed to be separate from the adjacent process chamber, and in that the beam-deflection device and the at least two process chambers are positioned in a processing position with respect to one another. This invention is carried out by a process for producing a three-dimensional shaped body, wherein in a first process chamber a layered build-up is carried out by successive consolidations of layers of a pulverulent build-up material, which is consolidated by means of electromagnetic radiation or particle radiation, to produce a shaped body, and at least a cooling, an extraction of build-up material that has not been consolidated, a removal of the finished component, a conversion or setting-up for the production of a new shaped body is carried out in at least a second process chamber.  
      The apparatus according to the invention significantly improves the economics of the production of shaped bodies. A shaped body is completely produced in a first process chamber, while cooling and unloading of the previously produced shaped body take place in at least one further process chamber, or the process chamber is converted or set up for a shaped body which is to be produced subsequently. This results in a high utilization of the capacity of the beam source, since it is transferred to the next process chamber immediately after a shaped body has been produced, in order to produce the next shaped body in the at least one further process chamber.  
      Furthermore, the formation of at least two hermetically locked process chambers allows a shaped body to be built up using a defined material in a first process chamber, whereas a shaped body can be built up using the same material powder or a material powder which is different from the first shaped body can be built up in at least one further process chamber. This arrangement is of particular importance for use in medical technology, since a high degree of purity of the material powders used is required.  
      Furthermore, the apparatus according to the invention has the advantage that it is possible to realise layers without the need for an operator, since a number of shaped bodies which corresponds to the number of process chambers can be produced in direct succession without any intervention from an operator.  
      The positioning of the at least one beam-deflection device directly to a process chamber, furthermore, provides good accessibility to the second or further process chambers in order for the shaped bodies produced to be removed and to allow the process chamber to be converted or set up for a subsequent working process as required.  
      The hermetically locked configuration of the process chamber also has the advantage that it is possible to produce a shaped body without any influence from immediately adjacent conversion work, cooling processes, impurities from the environment or the like.  
      According to an advantageous configuration of the invention, it is provided that each process chamber has an extraction means for build-up material that has not been consolidated, which extraction means comprises at least one barrier device. This barrier device prevents build-up material from being extracted from a process chamber which is currently carrying out the layered build-up of a shaped body when extraction of the build-up material that has not been consolidated is being carried out in a further process chamber. The working processes in one process chamber can proceed without interference from and independently of the working processes in the adjacent process chambers.  
      Furthermore, arranging the barrier devices in a closed position with respect to the process chamber has the advantage that a shielding gas atmosphere is maintained during the working process for consolidation of the individual powder layers. This increases the process reliability and, at the same time, ensures that there is only a low consumption of shielding gas.  
      According to a further advantageous configuration of the invention, it is provided that a fan is provided for the at least two process chambers, and at least one barrier device is provided in the extraction means between the fan and each process chamber. To reduce the overall space required and also the costs, by way of example a fan is provided, which is designed for operation for at least two process chambers. This also makes it possible to simplify the structure. To hermetically lock the process chambers and to operate them independently of one another, at least one barrier device is arranged in the extraction means between the fan and each process chamber, so that when the fan is operated extraction by suction is carried out at that process chamber in which the shaped body has been fully produced, while there is no extraction by suction for the other, further process chambers. This makes it possible to eliminate the possibility of the process chambers influencing one another when common component parts are used.  
      The process chambers have inlet openings, which can advantageously each be closed by a barrier device. The barrier devices are therefore assigned directly to the process chamber, so that further disruptive influencing factors are eliminated. The barrier devices of the inlet openings may be actuable together with the barrier devices of the outlet openings.  
      According to a preferred embodiment, the barrier devices are provided at least in an outlet opening which is in communication with a build-up chamber and with a powder trap. This provides for the hermetic locking of the process chamber. In addition, it is possible to provide for a feed opening, which supplies a volumetric flow during extraction of the process chamber, likewise to be closable by a barrier device. It is preferable for a barrier device to be provided in an outlet opening of a manual extraction device. This manual extraction device is used for manual extraction of powder residues. Consequently, the hermetic locking and the use of the fan can be optimized.  
      Each barrier device can preferably be actuated separately or jointly as a group for each process chamber by means of a control and arithmetic unit. This allows autonomous operation of the process chambers and process monitoring.  
      According to an advantageous embodiment of the invention, the barrier devices are designed as pinch valves and can preferably be actuated pneumatically. These pinch valves have the advantage of being virtually free from wear and having short reaction times. As an alternative to pneumatic actuation, it is also possible to provide hydraulic, electrical or electromagnetic actuation.  
      Furthermore, to make each process chamber autonomous, it is advantageously provided that the extraction of build-up material that has not been consolidated comprises a separation device and a filter. This allows the build-up material which has not been fused and consolidated to be recycled without impurities, for example from a further material from an adjacent process chamber, so that it is possible to reduce the amount of material used and, at the same time, ensure the purity of the processed materials on account of a closed circuit. It is advantageously provided for the powder which has been removed from the process chamber to be processed further by screening or the like. This further processing or preparation may be provided by a device provided in the apparatus or externally, and in the case of the latter, external option, it is preferable to form an interface with the separation apparatus, for which purpose a collection vessel is provided exchangeably for the external purification and preparation or further processing of the powder.  
      According to a further advantageous configuration of the invention, it is provided that there is a suction fan for at least two process chambers, which is in each case connected downstream of a separation apparatus belonging to the process chamber, for the extraction of build-up material that has not been consolidated and for the cooling of the process chamber and preferably the building platform. This allows isolated separation of the build-up material that has not been consolidated while using a common fan, in order to maintain the separation between the build-up materials used in the respective process chamber. It is preferable for the barrier device to be arranged upstream of the filter and the separation device, close to the process chamber. Each hermetically sealed process chamber is accessible through a closable opening facing towards the beam-deflection apparatus. This makes it possible to provide good accessibility to the process chamber, provided that the beam-deflection device is positioned at the further process chamber.  
      It is advantageously provided that the closable opening comprises a region which substantially transmits the electromagnetic radiation and is at least larger than a building platform provided on a lifting table for receiving at least one shaped body. This creates sufficient space for the electromagnetic radiation to be introduced. At the same time, the operating staff can carry out a visual check and monitoring of the process chamber. The transparent region provided in the closable opening is preferably formed from a glass, which preferably comprises two surfaces provided with an antireflection coating. This allows optimum beam introduction and optimum impingement of the radiation on the layer which is to be built up.  
      To hermetically lock the process chamber, it is advantageously provided that a feed device for supplying the build-up material is provided in a position which closes off the process chamber at least after the build-up material has been fed into the process chamber. This configuration makes it possible to prevent oxidation from the penetration of air during fusion of the build-up material and to prevent undefined cross sections from being built up by the introduction of further build-up material. At the same time, it is possible to prevent powder which is intended for build-up purposes being sucked into the process chamber during the process of extracting build-up material that has not been consolidated following production of the shaped body.  
      A seal is provided for the purpose of sealing between the process chamber and a cover which can be closed by the opening. As a result, a seal for hermetic locking is formed in a simple way. Shielding or inert gas is fed to and discharged from the process chamber while the layers are being built up. A closed circuit resulting from the closed process chamber and line routing reduces the operating costs.  
      Furthermore, to hermetically lock the process chamber, it is advantageously provided that at least one seal or a sealing configuration of the parts is provided between the carrier for receiving a shaped body and a build-up chamber surrounding the carrier. During fusion, the process chamber is filled with shielding or inert gas and is operated at a superatmospheric pressure, in order to prevent oxygen from entering the process chamber.  
      To hermetically lock the process chamber, it is advantageously provided that an encircling groove with a sealing ring is arranged on a lifting table which is part of a carrier. The diameter of this sealing ring is preferably designed to be slightly variable, so that a configuration with sealing contact is produced as a result of the different levels of heating during production of the shaped body.  
      It is preferable for the sealing ring to be formed from a material which is worn to a greater extent than the peripheral wall of the build-up chamber. As a result, simple replacement of the sealing ring after multiple use is sufficient to achieve a sealed arrangement in the build-up chamber.  
      The peripheral wall of the build-up chamber preferably has a surface hardness which is higher than that of the build-up material. As a result, it is possible to form a low-maintenance build-up chamber. It is advantageous for the build-up chamber to be surface-coated, preferably chromium-plated.  
      Furthermore, it is advantageous for a sealing ring or stripper to be provided adjacent to or assigned to an end face of the building platform, in order to form a first seal. This stripper, which is advantageously designed as a felt ring, has the advantage that it is possible to compensate for a relatively extensive temperature variation between the peripheral wall of the build-up chamber and the building platform. To increase the quality of the shaped body, the building platform is heated, so that temperature differences which lead to differing expansion of the building platform and the build-up chamber are produced between the building platform and the peripheral wall of the build-up chamber and are compensated for by the stripper.  
      Furthermore, for hermetic locking of the process chamber, it is advantageously possible to provide a shaft seal which is provided on a lifting rod of the lifting table. According to a further advantageous configuration of the invention, a beam-deflection device which can be positioned with respect to the individual process chambers is provided. This makes it possible to reduce the production costs for the apparatus according to the invention by virtue of the fact that a common beam source and a common beam-deflection device are used irrespective of the number of process chambers.  
      For simple, correct positioning of the beam-deflection device, it is advantageous to provide a linear guide, along which the beam-deflection device can be displaced and can preferably be positioned accurately with respect to the process chamber. The linear guide is advantageously arranged at a low height above the respective process chamber, so that there is a short distance between the deflection device and the layer which is to be built up in order to produce a shaped body in order in particular to achieve a narrow width of the fused track.  
      According to an alternative configuration of the invention, there is provision for the at least two process chambers to be displaceable with respect to the beam-deflection device. By way of example, it is possible to provide a type of turret arrangement or to provide a plurality of process chambers in a row, which process chambers can be displaced with respect to a stationary beam-deflection device. In particular in the case of a turret-like arrangement, it is possible to achieve very high utilization of the beam source and unsupervised production of shaped bodies over a prolonged period of time.  
      According to a preferred embodiment of the invention, it is provided that at least two hermetically locked, separate process chambers and a beam source and a beam-deflection device, which can be positioned at at least two process chambers, are provided in a machine housing in order to form a multichamber system. This apparatus has the advantage that those components which ensure autonomous operation of each process chamber are provided multiply, and those components which are required for the overall installation to function are provided just once. This makes it possible to create an apparatus which allows high utilization of the beam source and at the same time is optimized in terms of production costs.  
      In particular, the apparatus according to the invention makes it possible to carry out a process for producing a three-dimensional shaped body in which complete production of a shaped body is carried out in a first process chamber, with cooling and unloading of a finished shaped body, conversion or setting up of the process chamber for the production of a further shaped body being possible in parallel in at least a second process chamber. This creates the conditions for economic production of shaped bodies. Furthermore, it is possible to process different materials. The hermetically locked process chambers enable different process parameters to be run in order to satisfy particular demands on the build-up, the surface quality and on a low-stress, crack-free build-up of the shaped bodies.  
      According to a preferred embodiment, each process chamber has at least one inlet opening leading into the process chamber and at least one outlet opening leading away from it for shielding or inert gas. As a result, a suitable shielding gas or inert gas can be supplied as a function of the material used to build up the shaped body. Consequently, the respective process chambers are configured completely independently of one another and can be set to specific requirements for production of a shaped body.  
      According to an advantageous embodiment of the process, it is provided that barrier devices for the at least one further process chamber are held in a closed position during the extraction of build-up material that has not been consolidated or the cooling of a shaped body that has been produced in a process chamber. As a result, the process chambers are hermetically locked with respect to one another, and the working steps which take place and are ongoing in the respective process chambers do not influence one another. This increases utilization of the apparatus and improves the quality of the shaped body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention and further advantageous embodiments and refinements thereof are described and explained in more detail below on the basis of the examples illustrated in the drawings. According to the invention, the features revealed in the description and the drawings can be employed individually on their own or in any desired combination. In the drawings:  
       FIG. 1  shows a diagrammatic side view of an apparatus according to the invention,  
       FIG. 2  shows a diagrammatic sectional illustration of a process chamber in a working position during production of a shaped body,  
       FIG. 3  shows a diagrammatic sectional illustration of the process chamber shown in  FIG. 2  after layered build-up of a shaped body, in a cooling position,  
       FIG. 4  shows a diagrammatic sectional illustration of the process chamber shown in  FIG. 2  after layered build-up of a shaped body in an extraction position,  
       FIG. 5  shows a diagrammatic part-section through a process chamber with a feed device, and  
       FIG. 6  shows a diagrammatic illustration of two process chambers and a connection between the associated components. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
       FIG. 1  diagrammatically depicts an apparatus  11  according to the invention for the production of a three-dimensional shaped body by successive consolidation of layers of a pulverulent build-up material. The production of a shaped body by laser fusion is described, for example, in DE 196 49 865 C1. The apparatus  11  comprises a beam source  16 , which is arranged in a machine frame  14 , in the form of a laser, for example a solid-state laser, which emits a directed beam. This beam is focused via a beam-deflection device  18 , for example in the form of one or more actuable mirrors, as a deflection beam onto a working plane in a process chamber  21 . The beam-deflection device  18  is arranged such that it can be displaced by motor means along a linear guide  22  between a first process chamber  21  and a further process chamber  24 . The beam-deflection device  18  can be moved into a precise position with respect to the process chambers  21 ,  24  by means of actuating drives. Furthermore, the machine frame  14  provides a control and arithmetic unit  26  for operation of the apparatus  11  and for setting individual parameters for the working processes used to produce the shaped bodies.  
      The first process chamber  21  and at least one further process chamber  24  are arranged separately from one another and are hermetically isolated from one another.  
       FIG. 2  illustrates the process chamber  21 , by way of example, fully in cross section. The process chamber  21  comprises a housing  31  and is accessible through an opening  32  which can be closed off by at least one closure element  33 . The closure element  33  is preferably designed as a pivotable cover which can be fixed in a closed position by locking elements  34 , such as for example toggle lever elements. A seal  36 , which is preferably formed as an elastomer seal, is provided at the housing  31 , close to the opening  32 , to seal off the process chamber  21 . The closure element  33  has a region  37  which transmits the electromagnetic radiation of the laser beam. It is preferable to use a window  38  made from glass or quartz glass which has antireflection coatings on the top side and the underside. The closure element  33  may preferably be of water-cooled design.  
      The process chamber  21  comprises a base surface  41 . A build-up chamber  42 , in which a carrier  43  is provided and guided such that it can move up and down, opens out into this base surface  41  from below. The carrier  43  comprises at least one base plate  44 , which is driven such that it can be moved up and down by means of a lifting rod or lifting spindle  46 . For this purpose, a drive  47 , for example a toothed belt drive, is provided to move the fixed lifting spindle  46  up and down. The base plate  44  of the carrier  43  is cooled by a fluid medium, which preferably flows through cooling passages in the base plate  44 , at least during the layered build-up. An insulation layer  48  made from a mechanically stable, thermally insulating material is arranged between the base plate  44  and the building platform  49  of the carrier  43 . This prevents the lifting spindle  46  from being heated by the heating of the building platform  49 , with an associated effect on the positioning of the carrier  43 .  
      An application and levelling device  56 , which applies a build-up material  57  into the build-up chamber  42 , moves along the base surface  41  of the process chamber  21 . A layer is built up on the shaped body  52  by selective fusion of the build-up material  57 .  
      The build-up material  57  preferably comprises metal or ceramic powder. Other materials which are suitable and used for laser fusion and laser sintering are also employed. The individual material powders are selected as a function of the shaped body  52  to be produced.  
      On one side, the process chamber  21  has an inlet nozzle  61  for the supply of shielding gas or inert gas. At an opposite side, there is an extraction nozzle or extraction opening  62  for removing the supplied shielding or inert gas. During production of the shaped body  52 , a laminar flow of shielding or inert gas is generated, in order to avoid oxidation during fusion of the build-up material  57  and to protect the window  38  in the closure element  33 . It is preferable for the hermetically locked process chamber  21  to be held at a superatmospheric pressure of, for example, 20 hPa during the build-up process, although significantly higher pressures are also conceivable. This means that it is impossible for any atmospheric oxygen to penetrate into the process chamber  21  from the outside during the build-up process. During circulation of the shielding or inert gas, it is simultaneously also possible to realise cooling. It is preferable for cooling and filtering of the shielding or inert gas to remove entrained particles of the build-up material  57  to be provided outside the process chamber  21 .  
      The build-up chamber  42  is preferably of cylindrical design. Further geometries may also be provided. The carrier  43  or at least parts of the carrier  43  are matched to the geometry of the build-up chamber  42 . In the build-up chamber  42 , the carrier  43  is moved downwards with respect to the base surface  41  in order to effect a layered build-up. The height of the build-up chamber  42  is matched to the build-up height or the maximum height to be built up for a shaped body  52 .  
      A peripheral wall  83  of the build-up chamber  42  directly adjoins the base surface  41  and extends downwards, this peripheral wall  83  being suspended from the base surface  41 . At least one inlet opening  112  is provided in the peripheral wall  83 . This inlet opening  112  is in communication with a feed line  111  which accommodates a filter  126  outside the housing  31 . Ambient air is fed to the build-up chamber  42  through the inlet opening  112  via the filter  126  and the supply line  111 . Furthermore, the build-up chamber  42  has at least one outlet opening  113  in the peripheral wall  83 , to which outlet opening there is connected a discharge line  114  which leads out of the housing  31  and opens out into a separation device  107 . Downstream of the latter there is a filter  108  which discharges the volumetric flow that has been discharged from the build-up chamber  42  via a connecting line  118 . It is advantageously provided that the inlet opening  112  and the outlet opening  113  are aligned with one another. It is also possible for the openings  112 ,  113  to be arranged offset with respect to one another, both in terms of the height and in terms of their feed position in the radial direction or at right angles to the longitudinal axis of the build-up chamber  42 .  
      The building platform  49  is composed of a heating plate  136  and a cooling plate  132 . Heating elements  87  are illustrated by dashed lines in the heating plate  136 . Furthermore, the heating plate  136  comprises a temperature sensor (not shown in more detail). The heating elements  87  and the temperature sensor are connected to supply lines  91 ,  92 , which in turn are routed through the lifting spindle  46  to the building platform  49 . A peripheral groove  81 , in which one or more sealing rings  82  are fitted, is provided at the external periphery  93  of the building platform  49 ; the diameter of the sealing ring(s)  82  can be altered slightly and matched to the installation situation and temperature fluctuations. The sealing ring(s)  82  bear(s) against a peripheral wall  83  of the build-up chamber  42 . This sealing ring  82  has a surface hardness which is lower than that of the peripheral wall  83 . The peripheral wall  83  advantageously has a surface hardness which is greater than the hardness of the build-up material  57  provided for the shaped body  52 . This makes it possible to ensure that there is no damage to the peripheral wall  83  during prolonged use, and only the sealing ring  82 , as a wearing part, has to be replaced at maintenance intervals. It is advantageous for the peripheral wall  83  of the build-up chamber  42  to be surface-coated, for example chromium-plated.  
      The base plate  44  comprises a water cooling system which is in operation at least while the shaped body  52  is being built up. Cooling liquid is fed to the cooling passages provided in the base plate  44  via a cooling line  86  which is fed to the base plate  44  through the lifting spindle  46 . The cooling medium provided is preferably water. The cooling allows the base plate  44  to be set, for example, to a substantially constant temperature of 20° C. to 40° C.  
      To receive a shaped body  52 , the carrier  43  has a substrate plate  51  which is positioned fixedly or releasably on the carrier  43  by means of a retaining means and/or an orientation aid. Before production of a shaped body  52  commences, the heating plate  136  is heated to an operating temperature of between 300° C. and 500° C., in order to allow the shaped body  52  to be built up with low stresses and without cracks. The temperature sensor (not shown in more detail) records the heating temperature or operating temperature while the shaped body  52  is being built up.  
      The building platform  49  has cooling passages  101 , which preferably extend transversely throughout the entire building platform  49 . It is possible to provide one or more cooling passages  101 . The position of the cooling passages  101  is, for example, illustrated adjacent to the insulating layer  48  in accordance with the exemplary embodiment. Alternatively, it is possible for the cooling passages  101  to extend not just beneath heating elements  87  but also above and/or between the heating elements  87 .  
      After completion of the shaped body  52 , the carrier  43  is lowered from the position illustrated in  FIG. 2  into a first position or cooling position  121 . This position is illustrated in  FIG. 3 . Even while the carrier  43  is being lowered, a volumetric flow from the environment can be fed via the filter  126  and the supply line  111  to the build-up chamber  42  and discharged from the build-up chamber  42  via the outlet opening  113  and discharge line  114 . The build-up chamber  42  can be cooled as early as at this stage and also while the shaped body  52  is being built up.  
      The cooling position  121  of the carrier  43  is provided in such a manner that cooling passages  101  of the building platform  42  are aligned with the at least one inlet opening  112  and at least one outlet opening  113  in the peripheral wall  83  of the build-up chamber  42 . The volumetric flow flows through the cooling passages  101 , thereby cooling at least the building platform  49 . The cooling may be effected by a pulsed suction stream. The cooling rate in the shaped body  52  can be determined by the pulse/pause ratio. It is preferable to provide for uniform cooling for a predetermined period of time, to minimize the build-up of internal stresses in the shaped body  52 . The cooling may also be provided by a volumetric flow which continuously increases or decreases in quantitative terms. It is also possible to alternate between an increase and a decrease in order to obtain the desired cooling rate. The cooling rate can be recorded by the temperature sensor provided in the heating plate  136 . At the same time, the residual temperature of the shaped body  52  can be derived via this temperature sensor. This cooling position  121  is maintained until the shaped body  52  has been cooled to a temperature of, for example, less than 50° C. At the same time, the base plate  44  can be cooled further in this cooling position  121 . In addition it is also possible to provide for cooling passages or cooling hoses to be provided adjacent to the peripheral wall  83  of the build-up chamber  42  or in the peripheral wall  83  of the build-up chamber  42 , these cooling passages or cooling hoses also contributing to cooling of the build-up chamber  42 , the shaped body  52  and the carrier  43 .  
      After the shaped body  52  has been cooled to the desired or preset temperature, the carrier  43  is transferred into a further position or suction position  128 , which is illustrated in  FIG. 4 . This suction position  128 , which is illustrated by way of example, is used to remove, in particular suck out, the build-up material  57  which has not been consolidated during production of the shaped body  52 . The build-up chamber  42  is closed by a closure element  123  prior to the application of a suction stream flowing through the build-up chamber  42 . This closure element  123  has securing elements  124  which act on or in the opening  32  in order to fix the closure element  123  tightly to the build-up chamber  42 . The closure element  123  is preferably of transparent design, so that it is possible to monitor the sucking-out of build-up material  57  that has not been consolidated. A suction stream flowing through the build-up chamber  42  generates a swirl in the build-up chamber  42 , with the result that the build-up material  57  that has not been consolidated is sucked out and fed to the separation device  107  and the filter  108 . At the same time, furthermore, the suction is responsible for cooling the build-up chamber  42 , the shaped body  52  and the building platform  49 . In addition, it is possible to effect a further supply of air via at least one nozzle in the closure element  123 .  
      The sucking-out of the build-up material  57  can be operated by a constant volumetric flow, a pulsed volumetric flow or a volumetric flow with an increasing or decreasing mass throughput. The suction is terminated after a predetermined duration of the suction or after a period of time which can be set by the operating staff.  
      To remove the shaped body  52 , the closure element  123  is removed from the build-up chamber  42  and the carrier  43  moves into an upper position, so that the shaped body  52  is positioned at least partially above the base surface  41  of the process chamber  21  in order to be removed.  
       FIG. 5  illustrates an exemplary embodiment for feeding the build-up material  57  via a feed device  72  into the process chamber  21 . The partial section shows a feed passage  71  which is in communication with a collection vessel or storage vessel (not shown in more detail) and provides build-up material  57 . The feed device  72  comprises a slide  73 , which preferably has a slot-like opening  74  which, in a first position, enables the build-up material  57  to pass into the opening  74 . After the slide  73  has been positioned in a second position, the build-up material  57  stored in the opening  74  is conveyed via a gap  76  into the application and levelling device  56 , which then transfers the build-up material  57  into the build-up chamber  42  as a result of a reciprocating movement indicated by arrow  77 . Cutouts  79 , through which excess build-up material  57  can be discharged into a receptacle or powder trap  80 , are provided in the base surface  41  at the reversal points for the reciprocating movement of the application and levelling device  56 . Therefore, after the build-up material  57  has been introduced into the build-up chamber  42 , the base surface  41  is substantially free of build-up material  57 . This configuration of the feed device  72  allows a portioned supply of build-up material  57  into the process chamber  28 . Furthermore, this feed device  72  allows a rapid and simple change from one build-up material  57  to another build-up material  57 , since this feed device  72  allows the build-up material  57  to be introduced into the process chamber  21  virtually without residues. Further solutions relating to the configuration of the feed device  72  are likewise possible. By way of example, the portioned supply of the build-up material  57  may also be effected by means of a controllable closure element and a sensor element by which the feed quantity is determined. It is also possible, as an alternative to the application and levelling device  56  described, to use a device which introduces the build-up material  57  into the build-up chamber  42  in the style of a printing process.  
      The double-chamber or multi-chamber principle is described below with reference to  FIG. 6 , which shows a diagrammatic plan view of the apparatus  11  according to the invention, reference also being made at the same time to the previous figures.  
      Each process chamber  21 ,  24  comprises a filter  126 , through which purified ambient air is fed to a build-up chamber  42  via a feed line  111 . A discharge line  114  discharges the volumetric flow from the build-up chamber  42 , and this flow, outside the housing  31 , is fed to a separation device  107 . A filter  108  is connected downstream of the separation device  107 . Furthermore, the process chamber  21 ,  24  in each case comprises a line  106  which discharges the build-up material  57  that has been collected in a powder trap  80  from the housing  31  and feeds it to the separation device  107  or the discharge line  114 . This line  106  is in communication with an outlet opening of the powder trap  80  in the housing  31 , through which build-up material  57  that is not required is collected.  
      Each process chamber  21 ,  24  is assigned barrier devices  176  designed as shut-off valves. In a preferred embodiment, these barrier devices  176  are provided in the outlet opening  113  of the discharge line  114  and in the outlet openings of the powder traps  80  into which the lines for discharging powder open out. Furthermore, these barrier devices  176  may be provided between the process chamber  21 ,  24  in a line section of the discharge line  114  and the line  106  upstream of a separation device  107 . Furthermore, it is advantageously provided that a barrier device  176  is also provided in a suction line  117  of a nozzle  116  for the manual extraction of build-up material  57  that has not been consolidated or assigned to the nozzle  116 . In addition, to increase reliability, it is possible to provide further barrier devices  176 . By way of example, it is possible to provide a barrier device  176  in the inlet opening  112  of the feed line  111 . Furthermore, it is additionally possible to provide a barrier device  176  in the connecting lines  118  which in each case open out from the process chamber  21 ,  24  into the fan  109  in order to form further safety functions.  
      The barrier devices  176  can be actuated individually or combined in functional groups, so that the actuation is incorporated in the individual working processes, such as production of the shaped body, cooling of the carrier and extraction of the build-up material  57  that has not been consolidated. This ensures that, for example during the extraction of build-up material  57  that has not been consolidated or during cooling of the carrier  43  in the process chamber  21 , the process chamber  24  is hermetically locked off from the process chamber  21  by closing the barrier devices  176  of the process chamber  24 . It is preferable for the barrier device  176  used to be pinch valves, which have a long service life.  
      The barrier devices  176  are preferably actuated as a function of the position of the carrier  43  in the build-up chamber  42 . Furthermore, it is also possible for the signal for actuation of the barrier devices  176  to be coupled to the control signal for operation of the fan  109 . It is preferable for all the barrier devices  176  to be closed in their at-rest position and for only the required barrier devices  176  to be opened during the suction and/or cooling in a process chamber  21 ,  24 .  
      Furthermore, a suction line  117 , which has a nozzle  116  for manual cleaning of the process chamber  21 ,  24  and the further surroundings of the process chamber  21 ,  24 , opens out into the separation device  107 .  
      A sensor element, which automatically switches on the fan  109  when the nozzle  116  is removed from the holder for the purpose of manual extraction by suction and opens the associated barrier device  176 , so that the nozzle  116  is ready for operation, is provided at the nozzle  116  or at a frame for receiving the nozzle  116 . The further barrier devices  176  remain closed.  
      The at least two process chambers  21 ,  24  furthermore preferably each have a separate cooling system  103  ( FIG. 1 ), which cools components in and at the housing  31 .  
      The air/gas which has been discharged from the build-up chamber  42  and the discharged build-up material  57  are therefore each fed to a separation device  107 , assigned to each process chamber  21 ,  24 , and a filter  108  connected downstream thereof. The separation device  107  comprises a collection vessel, in which the discharged build-up material  57  is collected. This collected build-up material  57  can be purified by a sieve arranged between the separation device  108  and the collection vessel or can be fed to an external preparation installation, in order subsequently to be used, via the feed device  72 , for further layered build-up of a shaped body  52 . The separate suction which is provided for each process chamber  21 ,  24  makes it possible to use different build-up materials while preventing mixing or contamination of the build-up material  52 . In particular the barrier devices  176  prevent the respective circuits formed for each process chamber  21 ,  24  from influencing one another or becoming mixed with one another.  
      Furthermore, the apparatus according to the invention advantageously has an extinguishing installation which is provided for each process chamber  21 ,  24  and is at least partially integrated in the respective suction system. In the suction system there is a thermal monitoring element which monitors the temperature in the suction system. As soon as a limit value, which can be set and adapted to the build-up material  57 , is exceeded, this monitoring element emits an emergency stop signal to the control and arithmetic unit  26 . The fan  109  is then shut down. At the same time, the lines  106 ,  114 ,  117 ,  118 , like the filter  108  and the separation device  107 , are filled with shielding or inert gas and the barrier devices  176  are closed. The result of this measure is that the oxygen required for possible combustion is displaced by the shielding gas. This extinguishing installation has the advantage that following a cleaning process all the component parts can be used for the further production of shaped bodies  52 .  
      At least two process chambers  21 ,  24  are operated jointly by one fan  109 . This fan  109  is preferably designed as a radial fan and is connected, via connecting lines  118 , to the respective separation devices  107  and filters  108  of the process chambers  21 ,  24 . This advantageous arrangement and configuration of the process chambers  21 ,  24 , and their assignment of component parts and the incorporation of barrier devices  176 , enables each process chamber  21 ,  24  to be autonomous and to be hermetically locked. A common beam source  16  and a common beam-deflection device  18  are also provided. The further components are provided in a number corresponding to the number of process chambers  21 ,  24 , making it possible to produce closed material circuits both for the build-up material  57  and for the shielding or inert gas.  
      While a shaped body  52  is being built up and produced in a process chamber  21 , it is possible to carry out changeover work or to suck out build-up material  57  that has not been consolidated and/or to cool the shaped body  52  in the at least one further process chamber  24 , without the adjacent process chamber(s) being affected. This allows optimum utilization of the beam source  16 . In addition, different shaped bodies  52  with different build-up materials  57  and production parameters can be built up in each process chamber  21 ,  24 .  
      The abovementioned principle is not restricted to double-chamber systems. Rather, it is also possible for three or more process chambers  21 ,  24  to be associated with one another. A beam-deflection device  18  may in each case be positioned with respect to the process chamber  21 ,  24 , in order to guide a diverted beam onto the desired location within the working plane. Alternatively, it is also possible for the beam source  16  and beam-deflection device  18  to be of stationary design and for the process chambers  21 ,  24  to be moved relative to the beam-deflection device  18 . By way of example, a turret arrangement is conceivable. In this configuration, it is also possible for both the beam-deflection device  18  and/or the radiation source  16  and the process chambers  21 ,  24  to be arranged displaceably relative to one another.