Abstract:
The present invention relates to a method for producing three-dimensional components, using a three-dimensional printing method, an auxiliary structure being additionally formed beyond an extension of the one or more components during the construction of components. The invention also relates to an auxiliary structure for components produced by means of three-dimensional printing methods, the auxiliary structure being constructed along with the component and extending beyond a dimension of the one or more components.

Description:
CLAIM OF PRIORITY  
       [0001]    The present application claims priority from German Application No. DE 102007033434, filed on Jul. 18, 2007 and is the National Phase of PCT Application PCT/DE2009/001073, filed on Aug. 06, 2007, disclosure of which is hereby in-corporated by reference herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present invention relates to a method for producing three-dimensional components, using a three-dimensional printing method. 
       BACKGROUND  
       [0003]    Methods for producing three-dimensional components have been known for some time. 
         [0004]    For example, a method for producing three-dimensional objects from computer data is described in the European patent specification EP 0 431 924 B1. In this method, a particulate material is deposited in a thin layer onto a platform, and a binder material is selectively printed on the particulate material, using a print head. The particle area onto which the binder is printed sticks together and solidifies under the influence of the binder and, if necessary, an additional hardener. The platform is then lowered by a distance of one layer thickness into a build cylinder and provided with a new layer of particulate material, which is also printed as described above. These steps are repeated until a certain, desired height of the object is achieved. A three-dimensional object is thereby produced from the printed and solidified areas. 
         [0005]    After it is completed, this object produced from solidified particulate material is embedded in loose particulate material and is subsequently removed therefrom. This is done, for example, using an extractor. This leaves the desired objects, from which the remaining power is removed, for example by brushing. 
         [0006]    Other powder-supported rapid prototyping processes work in a similar manner, for example selective laser sintering or electron beam sintering, in which a loose particulate material is also deposited in layers and selectively solidified with the aid of a controlled physical radiation source. 
         [0007]    All these methods are referred to collectively below as “three-dimensional printing method” or “3D printing method”. 
         [0008]    In all of these three-dimensional printing methods, the loose, unsolidified particulate material supports the structural body during and after construction of the structural body. However, additional support structures, which are necessary, for example, in a different layering method (the so-called stereolithographic method), are usually not required in the 3D printing method. 
         [0009]    This characteristic has so far been regarded as a great advantage of the 3D printing method, since manual post-processing of the components is not required in order to remove any support structures. 
         [0010]    However, if a method such as powder-supported rapid prototyping is used in order to produce a larger number of objects, a variety of problems may potentially arise. 
         [0011]    After they are completed, the parts are entirely covered by loose particulate material and are therefore initially not visible to the operator. If the operator uses an extractor to remove the loose particulate material, the produced objects are in danger of being damaged by the suction nozzle. In the case of small parts, in particular, the parts are also in danger of being unintentionally drawn into the suction nozzle. 
         [0012]    Large, filigree structures may also be damaged after production when they are removed from the powder bed, if parts of the object are still located in the powder bed and are somewhat more difficult to remove. 
         [0013]    It is also possible for components to become dislodged and slip or collapse under their own weight if the loose particulate material beneath the component is carelessly removed. 
         [0014]    For all of these reasons, it has not yet been possible to automate the removal of the components from the powder bed. 
       SUMMARY OF THE INVENTION 
       [0015]    An object of the present invention is therefore to provide a method and a device which make it possible to easily and safely remove any 3D-printed object from the loose particulate material. 
         [0016]    According to the invention, this object is achieved by a method for producing three-dimensional components using a three-dimensional printing method, an auxiliary structure additionally being formed beyond the extension of the one or more components during the construction of components. 
         [0017]    The object is also achieved by an auxiliary structure according to the invention for components produced by means of three-dimensional printing methods, the auxiliary structure being constructed along with the component and extending beyond a dimension of the one or more components. 
         [0018]    By additionally constructing an auxiliary structure of this type, it is a great deal easier to handle potentially small and filigree-structured components. 
         [0019]    According to a preferred embodiment of the method according to the invention, the auxiliary structure is additionally constructed in such a way that two simultaneously constructed components are interconnected directly or indirectly by the auxiliary structure. 
         [0020]    In such an embodiment of the present invention, it potentially become even easier to handle the produced components, since multiple components may be removed at the same time. This may be advantageous, in particular, if the components are relatively small. 
         [0021]    In a method according to the invention, the auxiliary structure may advantageously include materials of the component. 
         [0022]    Such an embodiment of the method according to the invention makes it easy to construct the auxiliary structure and also requires only a reasonable amount of additional time to construct the auxiliary structure. 
         [0023]    According to a particularly preferred embodiment of the present method, the auxiliary structure is largely formed from the same material as the one or more components. This potentially makes it particularly easy to additionally build the auxiliary structure. 
         [0024]    According to a particularly preferred embodiment of the method according to the invention, multiple layers of components are formed on top of each other. This means that, during a single build process, multiple components may be formed not only next to each other, but also on top of each other. In the event that particularly small or even only particularly flat components are to be constructed, this is a possible embodiment of the method. 
         [0025]    The auxiliary structure may have any conceivable shape. However, it may be advantageous if, in the event that multiple components are produced on top of each other, a separate auxiliary structure containing all components on a layer is formed on each layer of components. 
         [0026]    In the method, as described according to the invention, it is possible according to an embodiment of the present invention to form the component and the auxiliary structure with the aid of particulate materials deposited in layers and by adding a further material or by selectively applying energy. 
         [0027]    According to the method, the auxiliary structure is preferably formed in such a way that it is connected to at least one component. It is therefore also conceivable that in some embodiments it is advantageous to interconnect all components of a manufacturing process. 
         [0028]    It may also be advantageous to form predetermined break points at junctions between the component and auxiliary structure in the method according to the invention. 
         [0029]    According to an embodiment of the invention, it has also proven to be helpful if the auxiliary structure further forms a holder or coupling device, since this makes it particularly easy to handle the formed components. A holding device of this type may be a holder for a handling tool. 
         [0030]    A further improvement achievable by an auxiliary structure according to the present invention is that the auxiliary structure may enable the handling of components to be automated. 
         [0031]    To make the components particularly easy to handle, the auxiliary structure, according to one embodiment, connects at least two component on a component layer. 
         [0032]    It may also prove to be particularly advantageous if the auxiliary structure interconnects all constructed components. This makes it particularly easy to remove the components after they have been completed, and this may be done in a single operation. 
         [0033]    According to an embodiment of the invention, it may be useful to always orient the auxiliary structure on one side of the build cylinder in order to have a uniform starting point for any removal devices and then to group the desired components on this side, which saves space. Due to known build time considerations, it would then be possible for the rest of the auxiliary structure to follow the contours of the components as closely as possible. 
         [0034]    It would be possible to connect the auxiliary structure directly to the one or more components. 
         [0035]    A further possibility would be to connect the auxiliary structure indirectly to the one or more components, for the auxiliary structure does not necessary have to be integrally connected to the component. Embodiments are also conceivable in which the auxiliary structure holds the component in a positive fit or is even positioned a short distance away from the component, permitting slight movements of the component. 
         [0036]    It may also be possible to design the auxiliary structure as a kind of lattice box surrounding the component, which has only thin strips for separating the space segments. 
         [0037]    According to a particularly preferred embodiment of the present invention, the determination of the suitable auxiliary structure should be automated as much as possible in process-preparing software. 
         [0038]    For example, a possible workflow would be to place the parts to be built in the virtual build space, using a computing program. In a subsequent step, the operator marks the positions on the components for connecting the auxiliary structure. The process software subsequently computes the optimized auxiliary structure and also dimensions it on the basis of the available data relating to component volume and therefore weight. 
         [0039]    Next, the entire build space, including the auxiliary structure, is divided into the desired layers, and this data is then transferred to the layering process, which enables the component and the auxiliary structure to be constructed by means of the desired 3D printing method. 
         [0040]    The auxiliary structure may also be used to facilitate component identification, for example by applying component numbers or component codes to the strips for the corresponding components. These codes may be provided, for example, in machine-readable form so that they may be supplied to an automated evaluation system. 
         [0041]    According to a further embodiment of the invention, a method for producing three-dimensional components from a particulate base material is provided. The base material is deposited in layers and subsequently connected selectively along a contour of the component predetermined by a controller by adding a further material or applying energy. The component is completed by repeating this operation multiple times. In the present case, an auxiliary structure is preferably constructed along with the component, and this auxiliary structure holds the one or more components to be constructed in the desired position within the build space even without the supporting effect of the surrounding powder material. 
         [0042]    If, according to a particularly preferred embodiment of the present invention, the auxiliary structure has a different color than the component, it may be, for one thing, particularly easy to handle the components, since it is very easy even for a machine to determine what the auxiliary structure represents and where it should be possible to grip the formed structure. 
         [0043]    For the purpose of more detailed explanation, the invention is described in further detail below on the basis of preferred embodiments with reference to the drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]      FIG. 1  shows an auxiliary structure designed as a frame according to a first preferred embodiment of the present invention. 
           [0045]      FIG. 2  shows a possible shape of an auxiliary structure for connection to the components, according to a further embodiment of the present invention. 
           [0046]      FIG. 3  shows a system of multiple components in a build cylinder according to a third preferred embodiment of the method according to the invention. 
           [0047]      FIG. 4  shows an automated means of removing components provided with auxiliary structures. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0048]      FIG. 1  shows a top view of a connection of multiple components  1  having an auxiliary structure  2 , auxiliary structure  2  including a frame  4  surrounding components  1 . Components  1  are connected to frame  4  by strips  3 . 
         [0049]    According to the embodiment of the invention illustrated in  FIG. 1 , auxiliary structure  2  includes frame  4 , which surrounds components  1  on a plane and is connected to the individual components by strips  3 . Frame  4  is dimensioned in such a way that all components  1  connected thereto are held on this frame  4  by the force of their own weight without damaging the frame. 
         [0050]    To limit the amount of powder consumed, it is possible to provide at least part of auxiliary structure  2  with a non-solid design. For example, it would be possible to produce at least part of frame  4  from hollow or open profiles whose interiors may be accessible to cleaning agents via corresponding openings. 
         [0051]    For example, frame  4  may have a rectangular cross section; however other cross sections, such as round or oval ones, are also conceivable without further limitation. 
         [0052]    To shorten the build time for auxiliary structure  2 , it may be advantageous, according to a preferred embodiment of the invention, to position auxiliary structure  2  as closely as possible to components  1  and thereby give it a minimal dimension. 
         [0053]      FIG. 2  shows a possible means of connecting an auxiliary structure  2  to a component  1  according to a further embodiment of the present invention. 
         [0054]    To limit post-processing work for removing strips  3  or the contact points of strips  3  on component  1 , it may be advantageous to provide auxiliary structure  2  with a minimal number of connecting points  10  to components  1 . 
         [0055]    Strips  3 , along with their connecting points  10 , may be designed with so-called predetermined break points  9  to facilitate removal, these predetermined break points being provided with a geometrically defined constriction  9 , as illustrated by way of example in  FIG. 2 . 
         [0056]    Alternatively or in addition, it would also be possible to produce predetermined break point  9  by reducing the solidity, for example by reducing the binder deposit. 
         [0057]    Connecting points  10  are also preferably located at points on components  1  which do not require an exact surface. It is thus undesirable for a poorly placed connecting point to mar the visual appearance. 
         [0058]    Preferred locations for connecting points  10  may be, for example, on the rear or inside surfaces of component  1 . However, when selecting connecting points  10 , it is also important to ensure that accessibility is maintained and that the connections may be removed without residue. For this reason, outwardly curved surfaces are potentially more suitable, since they are more easily accessible than inwardly curved surfaces. 
         [0059]    The number of connecting points  10  should preferably also be selected in such a way that they are sufficient to hold connected component  1  in any position by the force of its own weight and, if possible, also under the influence of weaker or stronger additional forces following post-processing work. 
         [0060]      FIG. 3  shows a system of multiple components  1  in a build cylinder  4  after components  1  have been constructed, according to a further preferred embodiment of the method according to the invention. 
         [0061]    In 3D printing as well as in other RP methods, it is possible to produce components in multiple layers on top of each other, depending on the component size and component shape. Access to the individual layers is usually only from one side, ordinarily from the side on which the particulate material is introduced. 
         [0062]    In order to reach the underlying components, the top components must first be removed. 
         [0063]    As shown in  FIG. 3 , it may therefore be advantageous to divide components  1  and associated auxiliary structures  2  into different planes which, if necessary, run parallel to the layering plane. This enables the individual “component planes” to be removed easily and successively. 
         [0064]    Auxiliary structures  2  of the individual planes should preferably be easily separated from each other and nevertheless be fixable in place without supporting powder material. 
         [0065]    Depending on the component size and component weight, it would also be conceivable to interconnect the components on different component planes via the auxiliary structure. 
         [0066]    It may also be advantageous if the auxiliary structure interconnects the component additionally or exclusively in a direction perpendicular to the layering direction, instead of in a direction parallel to the layering direction. 
         [0067]    Connecting the components to an auxiliary structure makes it possible to use automated removal and cleaning methods. This is currently made difficult by the fact that the components are usually designed individually and have no holding means, for example for robot grippers. The use of simple gripping mechanisms would quickly cause damage to the components. 
         [0068]      FIG. 4  shows an automated means of removing components  1  provided with auxiliary structures  2 , which is made possible through the use of the auxiliary structures. 
         [0069]    By using auxiliary structure  2 , it is possible, according to an embodiment of the present invention, to define a uniform holding means for automatic removal or cleaning or post-processing. 
         [0070]    A robot  7  would be able to successively remove an auxiliary structure  2  provided with a frame and including components  1  and to supply them to a post-processing process such as cleaning. 
         [0071]    Loose particle material  6  may also be more easily removed, for example by removing at least a portion of base  5  of the vessel where the layering process took place, or if the base has closable openings which are opened at the end of the process, and if the loose particulate material, which has a sufficient fluidity, flows out through the base openings. 
         [0072]    According to this technique, components  1  are held in the predetermined position by auxiliary structure  2  and are not carried along by outflowing particulate material  6 . 
         [0073]    However, it would also be possible to remove loose particulate material  6  via the upper opening in the build container, for example by tilting the entire build container in order to pour out loose particulate material  6 . If auxiliary structure  2  is held in place on the build cylinder, for example by clamps, components  1 , including auxiliary structure  2 , remain in the predefined position is not impaired by this operation and are therefore also not damaged. 
         [0074]    It would also be possible to extract loose particulate material  6 , as is known from the prior art. A suction lance may be positioned over the powder feedstock from above, or the suction lance is inserted directly into the powder feedstock, and the loose particulate material then flows to the suction nozzle. In both cases, components  1  remain in a desired position due to auxiliary structure  2 , and they are therefore not unintentionally extracted or damaged. 
         [0075]    After a large part of loose particulate material  6  has been removed, components  1 , including auxiliary structure  2 , may be removed from the build container and supplied to a further cleaning process. This may be done using compressed air or compressed air combined with blasting media. In this case, auxiliary structure  2  again enables components  1  to remain in a desired position and the cleaning agents to be passed over components  1 . This operation may be carried out manually or automatically. For example, it would be conceivable to use an automatic cleaning system into which multiple standardized auxiliary structure frames  4 , including components  1 , are introduced, and by means of which components  1  may be cleaned of remaining residual particulate material  6  in a closed process chamber, using a fluid medium such as compressed air. 
         [0076]    Particulate material  6  separated from component  1  may then be supplied to a separator via a process chamber extraction system and fed back into the build process. 
         [0077]    The strong flow rates needed in an automatic cleaning system of this type require components  1  to be sufficiently fixed in place, which may be accomplished with the aid of auxiliary structure  2 . 
         [0078]    After cleaning, components  1  may have to be infiltrated in order to achieve certain material properties. This may be accomplished by immersing the components into a tank filled with fluid infiltration medium  8 . 
         [0079]    This operation may be greatly facilitated by auxiliary structure  2 , since multiple components  1  may be easily held at once and thus also safely immersed at once. In this case, it is also possible to easily automate the operation by introducing one or more frames, for example into a lattice box, and then immersing them together with the lattice box into infiltration tank  8 , as shown, for example, in  FIG. 4 . Of course, it is also conceivable to automate the immersion of individual “component layers”. 
         [0080]    Finally, components  1  must be separated from auxiliary structure  2 . 
         [0081]    It is helpful to distinguish the auxiliary structure from the component with the aid of colors, which may be accomplished, for example, by applying additional dye during the 3D printing process or by means of a modified chemical reaction via overhardening or underhardening. A distinction may also conceivably be made by means of a particular surface structure which is used only in the auxiliary structure.