Patent Publication Number: US-2004045941-A1

Title: Device for sintering, removing material and/or labeling by means of electromagnetically bundled radiation

Description:
[0001] The invention relates to a device for sintering, removing material and/or labeling by means of electromagnetically bundled radiation, especially a laser sintering machine and/or laser surface-processing machine having the additional features of the precharacterizing clause of claim 1.  
       [0002] Known from DE 198 46 478 is a laser sintering machine where a construction space is accommodated in a machine housing in whose top area is located a scanner into which the beam of the sintering laser is coupled. Arranged under the scanner is a vertically displaceable working material platform, in the vicinity of which is provided a material-supplying device with a coater serving for supplying powder, paste or liquid sintering material from a supply container into the processing area above the working material platform. The work piece platform is removable from the construction space as a changeable element. Only sintering processes can be carried out with this device. Besides, after preparing a work piece, the non-sintered, loose powder must be returned to the supply chamber manually, using a sieve. Before producing a work piece with another sintering material, the supply container as well as the coater must be cleaned, which considerably lengthens the down times between two construction operations.  
       [0003] The object of the invention is to develop a device with the further features of patent claim 1, such that with it the down times between two construction processes are considerably shortened, and the device is more flexibly usable. This objective is met by the entire teaching of claim 1. Advantageous further configurations are obtained from the subclaims 2-26.  
       [0004] As core of the invention, first to be seen is that the vertically displaceable work piece platform, the supply container and the coater are constructed to be removed from the construction space as one process platform/changeable unit and, for carrying out similar or other processing operations, capable of being placed in the construction space are other process platform/changeable units of the same or similar configurations, e.g. without supply container and coater. Accordingly, the laser, with the optical components coupled to it, is appropriately separated from the work piece to be processed, or to be precise, from the required sintering material. Therefore, it is possible, immediately after ending a sintering process or some other work piece operation, to carry out the next processing operation merely by changing out the process platform/changeable units. The completely separate units additionally have the advantage that the laser is usable for different operations. Moreover, in the event of a damaged component in the area of the work piece to be processed, e.g. in the case of a defective coater, the laser machine can continue to be used without considerable down times. The entire device in accordance with the invention is, accordingly, usable in extremely flexible fashion, whereby between two processing operations only extremely short down times occur for changing out the replaceable units, and therewith the processing laser is better used to capacity.  
       [0005] Another process platform/changeable unit of a different construction can display a table-like clamping surface and therewith co-operating clamping elements for work pieces. The clamping surface is located on the work piece platform. This platform is, for example, suitable for labeling, ablation, welding or for distance measurement with the laser. The work piece platform or rather the clamping surface integrated into the changeable unit can in practice be constructed to be vertically displaceable, in order, e.g. to be able to set exactly the required distance to the scanner. In practice, however, the scanner is also appropriately displaceable in all directions, thus also in the vertical direction.  
       [0006] In advantageous further development, this additional process platform unit and/or the integrated work piece platform can be automatically rotatable about at least one vertical axis and/or pivotable about horizontal axes. This enables an extremely flexible processing of the work piece located on the work piece platform whereby, in particular, its edge surfaces, beveled surfaces or undercuts can be processed in simple fashion, with uniform quality, with the laser beam impinging thereupon. The rotatability and tiltability about the horizontal and/or the vertical axes can be accomplished by motorized drives that are in practice controlled by a process computer of the device. Thus an exact as well as a rapid and reproducible setting of an optimal position of the work piece platform is possible.  
       [0007] Limit (stop) elements can be provided in the construction space in order to be able to bring different process platform/changeable units into defined processing positions within definite, minimum bounds. In one particularly advantageous variant of embodiment the process platform/changeable units can display a coding that can be recognized by the laser elements of the device, so that an exact, automatically executable positioning of the process platforms is possible. Furthermore, because of the coding, it is possible for the device&#39;s process computer to select processing programs such as, e.g. sintering/fusing and/or labeling, ablation, welding, distance measuring and the like. In this way e.g. it is possible also to automatically set the radiation energy and focusing of the laser beam for the particular process.  
       [0008] The process platform/changeable units can in practice be made lockable in their processing position in the construction space with locking elements. To automatically line up the process platform/changeable units in a processing position, the locking elements can be motor driven.  
       [0009] To be able to execute a rapid and simple change out of the process platform/changeable units, the changeable units can be constructed as rolling modules provided with castors and capable of being placed into the construction space. To obtain a stable unit, the process platform/changeable units can display a box-like housing that simultaneously represents a protective jacket against external influences (e.g. against contamination or mechanical effects). Also capable of being arranged inside the box-like housing are motorized drives for changing the position or location of the work piece platform.  
       [0010] To guarantee optimal processing of the work pieces, it is possible, when bringing the process platform/changeable units into the construction space, to automatically produce electrical connections and/or (fluid) flow channel connections between the device and the changeable unit. The laser device and the processing device thus operate together as a unit. The flow channels serve for aeration with inert gas in the construction space to prevent oxidation of the work piece or of the working substance during the laser processing. In his case, the flow channels are preferably arranged such that there is produced in the construction space a defined laminar flow by injection and removal with inert gas, e.g. argon. Particularly advantageously, the inert gas that has already flowed through the construction space can be processed and re-supplied to the construction space. Capable of being arranged in or at the end of the flow channels are filters that clean the gas flowing through.  
       [0011] Additionally, each process platform/changeable unit can display a separate process contrivance, whereby there occurs a transfer of data to the laser device via a data transfer means located in the construction space. The guidance of the laser as well as the movement of the process platform can, therewith, be optimally synchronized to each other, so that exact laser beam guidance can be executed. The data transfer means can be constructed as optical interfaces and are, therefore, in great measure independent of contamination in the form of sintering material. Besides this contactless data transfer means, these means can additionally or alternatively display plug contacts.  
       [0012] Particularly advantageously, a position recognition device for the process platform/changeable units can be arranged in the construction space, whereby any platform positions or locations from the process computer of the device can be recognized and be taken into account at the time of run off of the applicable process technology.  
       [0013] Furthermore, the clamping elements can also be associated with a manipulator that can be controlled via the process computer and, therewith, hold the work piece in exactly the desired position.  
       [0014] Advantageously, the position of the clamped work piece can be automatically recognized. In this way, an exact processing of the work piece can be excecuted without having to position it precisely manually beforehand.  
       [0015] In one special form of embodiment, a removal device for loose and/or non-sintered powder in the vicinity of the work piece platform can be arranged on the process platform/changeable unit. In practice, the removal device can be integrated in the process platform/changeable unit. This automatic elimination of the excess powder can reliably prevent the machine user from coming into contact with the powder.  
       [0016] The removal device can advantageously be provided in the lower part of the process platform/changeable unit, since the work piece platform, after the construction process, is driven downwardly and the non-sintered powder can be removed there.  
       [0017] The removal device can include an evacuation device that is disposed in the lower part of the vertically displaceable work piece platform and, there, the loose powder is in great part evacuated. A conveying contrivance for transport of the powder into the supply container can be connected to the evacuation device. The conveying contrivance can here be constructed, for example, as a worm drive. In this method of returning the powder into the supply container, reliably prevented for one thing is that the powder become contaminated. The automatic return transport of the powder, for another thing, represents a special timesaving process step that replaces the extremely inconvenient, manual shoveling out of the powder. 
     
    
    
     [0018] The invention is explained in more detail with the aid of advantageous examples of embodiment in the sketches.  
     [0019] They show:  
     [0020]FIG. 1 a greatly simplified perspective representation of the device in accordance with the invention;  
     [0021]FIG. 2 a section through a simplified perspective representation of the device in a side view in accordance with the invention, and  
     [0022]FIG. 3 a section through a simplified representation of another process platform/changeable unit in a side view. 
    
    
     [0023] Reference number  1  designates overall the device for sintering, ablation and/or labeling by means of electromagnetically bundled radiation. In the case of device  1  we are dealing with a laser sintering and surface processing machine, with a construction space  3  accommodated in a machine housing  2  above which is disposed a scanner  4 , into which is coupled the beam of a sintering source of energy. The laser beam coming out from the scanner  4  is given the reference number  5 . The scanner  4  is displaceable in all directions via a cross slide support  6 . Located in the construction space  3  for carrying out stereographic construction procedures is a vertically displaceable work piece platform  7 , a supply container  8  and a coater  9 , which are constructed as a process platform/changeable unit  10  capable of being removed from the construction space  3  as a connected unit. For carrying out like or other processing operations, other process platform/changeable units  10  of the same or different designs can be brought into the construction space  3 , e.g. as can be seen in FIG. 3. Obtained with the process platform/changeable units  10  is a separation of the laser, or to be precise, optical components as well as the components to be processed, so that the device  1  is for one thing more flexibly usable, and for another thing the down times between the individual processing operations, e.g. because of cleaning measures or cooling procedures, are considerably reduced.  
     [0024] The process platform/changeable unit  10  in accordance with FIG. 2 essentially serves for carrying out the stereographic construction procedures. According to the sketch, the work piece platform  7  is vertically displaceable by means of a scissors jack  18 .  
     [0025] The other process platform/changeable unit  10  in accordance with FIG. 3 displays a table-like clamping surface  11  and therewith cooperating clamping elements  12 , with which the work piece to be processed can be positioned and held securely, especially during the processing operation. The work material platform  7  in the case of this changeable unit  10  is likewise constructed to be vertically displaceable by means of a scissors jack  18 . Besides the scissors jack  18 , there naturally exist other possibilities for vertical displacement, as e.g. a hydraulic or pneumatic drive unit. The process platform/changeable unit  10  is also automatically rotatable about a perpendicular axis  14 , whereby the scanner  4  and the work piece  13  can execute an increased number of motions relative to each other, and an optimal processing of the work piece  13  will be guaranteed. The other process platform/changeable unit  10  can also be tiltable about horizontal axes, of which a horizontal axis  15  is sketched in, for example in FIG. 3. Besides, there also exists the possibility that the process platform/changeable unit  10  can be tiltable about diagonal axes. tiltable about diagonal axes. Tiltability of the process platform/changeable unit  10  and/or the work piece platform  7  guarantees an optimal processing, e.g. of beveled surfaces or undercuts on work piece  13 . Rotatability and tiltability about the horizontal axis  15  and/or the vertical axis  14  is accomplished by (not represented in more detail in the sketches) motorized drives that are controlled by a process computer of device  1 , in order to bring about an exact setting (adjustment) of the process platform/changeable unit  10  or the work piece  7 .  
     [0026] As can be recognized in FIG. 1, provided in the construction space  3  are stop elements  16  in order to be able to bring different process platform/changeable units  10  into defined process positions.  
     [0027] Furthermore, each process platform/changeable unit  10  displays coding that is recognized by the laser elements of device  1 . Because of the coding, the process computer of the device  1  can select different process programs, such as e.g. sintering/fusing and/or labeling, welding, measuring distance, etc. Accordingly, processing of the work piece  13  can occur immediately after setting in the changeable unit  10 , without needing to program the process computer beforehand.  
     [0028] In order to stay in the set position during the processing operation, the process platform/changeable unit  10  can be locked in the construction space  3  with stop elements. The stop elements here are motor driven in order to automatically adjust the process platform/changeable unit  10  in a processing operation position. However, the stop elements are not represented in more detail in the sketch.  
     [0029] To guarantee a rapid and simple change out of the process platform/changeable units  10 , they are constructed as rolling modules equipped with castors  17  capable of being placed into the construction space  3 .  
     [0030] The process platform/changeable units  10  display box-like housings  18  in which are arranged the scissors jacks  19  as well as motorized drives for resetting the position or location of the process platform/changeable units  10  and/or the work piece plates  7 .  
     [0031] When bringing the process platform/changeable units  10  into the construction space  3 , electrical connections and/or flow channel connections are automatically provided between the device  1  and the process platform/changeable unit  10 . Additionally, each process platform/changeable unit  10  displays a separate processor device, whereby there follows a transfer of data over data transfer means disposed in the construction space  3 . The data transfer means can, for example, be constructed as optical interfaces that are, in particular, relatively insensitive to contamination. Additionally arranged in the construction space  3  is a location recognition device for the process platform/changeable units  10 . With this any process platform locations or positions are recognized by the process computer of device  1 , and are taken into account when running off the particular process technology. The flow channels  20  serve for conducting inert gas (e.g. argon) into the construction space  3 , where expended gas is processed, e.g. via filters and re-supplied to the construction space  3 . The flow channels  20  for inert gas conduction and recovery are represented in the sketches in accordance with FIG. 2 only in the changeable unit  10 . Naturally, it is also possible that the flow channels  20  also be integrated in the process platform/changeable unit  10  in accordance with FIG. 3, with which the work pieces  13  have material removed and are labeled. Additionally, it is then advantageous to close off to the outside the construction space  3  in which the work piece is located.  
     [0032] Besides this, the clamping elements  12  are disposed on a manipulator that can be controlled via the process computer, and that brings the clamped work piece  13  into the optimal processing position and holds it there during the processing operation. Moreover, the location of the clamped work piece  13  can be automatically recognized (e.g. by the location recognition device), so that an exact processing is possible without expensive positioning measures.  
     [0033] The process platform/changeable unit  10  in accordance with FIG. 2 further displays a removal device  21  for loose and/or non-sintered powder that falls in the area of the work piece platform  7 . The removal device  21  is provided in the lower region of the process platform/changeable unit  10 . After ending the construction process of the sinter work piece, the work piece platform  7  moves downward. There, the loose and/or incompletely sintered powder is suctioned off by the suctioning device  22 , to the removal device  21 . Connected to the suctioning device  22  is a conveying contrivance  23  that transports the powder into the supply container  8 . An automatic powder return that is extremely time saving is thereby obtained, and the returned powder is protected against contamination.