Patent Publication Number: US-2021178676-A1

Title: Apparatus and method for producing three-dimensional objects

Description:
The invention relates to an apparatus and a method for producing three-dimensional objects from a deformable material. 
     An apparatus for producing three-dimensional objects from a deformable material is known from U.S. Pat. No. 9,821,905 B2. 
     WO 2014/153535 A2 discloses a printer for three-dimensional objects in which a thread-like stiffening material, for example, is discharged with the actual printing material. 
     U.S. Pat. No. 5,936,816 describes an apparatus and a method for producing three-dimensional objects from a deformable material, wherein a reinforcing fiber is discharged with the deformable material. 
     U.S. Pat. No. 6,899,777 B2 describes a continuous extrusion process in which a ceramic, metal or plastic fiber is extruded together with a thermoplastic elastomer. 
     EP 2 676 784 A1 describes a method for producing an object by extrusion. In the method, a filament is fed to an extrusion head and discharged from it together with a matrix material. 
     US 2014/0232035 A1 describes an apparatus for producing objects by extrusion, which has an extrusion needle for extruding thermoplastic material together with several fiber strands. 
     U.S. Pat. No. 9,511,543 B2 discloses a method and an apparatus for the additive production of three-dimensional objects. Several materials are extruded simultaneously as one composite material. In this case, at least one material is present in liquid form and at least one material is present in solid form. 
     DE 10 2011 050 780 A1 describes a method and an apparatus for applying a continuous fiber to an object. This is done by an application nozzle to which a continuous filament and an impregnating material are fed. 
     However, the known solutions are relatively inflexible and can therefore generally be used only to a very limited extent. 
     Therefore, it is an object of the present invention to provide an apparatus and a method for producing three-dimensional objects from a deformable material allowing a more flexible application. 
     According to the invention, this object is achieved by the features mentioned in claim  1 . 
     With the apparatus according to the invention, it is possible to discharge different quantities of the deformable material due to the two discharge openings, which have different cross-sections. Each discharge opening can be closed or opened independently of the other, so that either a small amount of the deformable material can be discharged to the second discharge opening with a smaller cross-section or a larger amount of the deformable material can be discharged to the first discharge opening with a larger cross-section. Furthermore, it is possible to completely close the apparatus according to the invention so that no material can escape from it. This is particularly advantageous if the apparatus is to be moved between two points without discharging deformable material. 
     Due to this design, the apparatus according to the invention can be used very flexibly, since it is always possible—in contrast to known solutions—to discharge the desired amount of deformable material. When using the second discharge opening with the smaller cross-section, very fine surfaces can be produced, whereas when using the first discharge opening with the larger cross-section, it is possible to apply very large quantities of the deformable material and thus produce very large structures in a relatively short time. 
     In a very advantageous further embodiment of the invention, it may be envisaged that the second closing device is arranged within the cavity of the first closing device. This results in a very compact construction of the apparatus according to the invention. 
     In a further advantageous embodiment of the invention, if the first closing device for selectively closing and opening the first discharge opening is adjustable in its longitudinal direction by means of an adjusting arrangement, very fast closing or opening of the first discharge opening is possible on the one hand. On the other hand, the cross-section of the first discharge opening can thereby be adjusted continuously in principle, as it is possible to position the first closing device in any position between complete opening and complete closing of the first discharge opening. Furthermore, such a solution allows a relatively simple design of the drive of the adjusting arrangement for adjusting the closing device, which can be provided so as to require little installation space. 
     Another advantageous embodiment of the invention may consist in that the second closing device for selectively closing and opening the connecting bore is adjustable in its longitudinal direction by means of an adjusting arrangement. If the second closing device is also adjustable in its longitudinal direction, similar advantages result as with the adjustment of the first closing device in its longitudinal direction. Furthermore, the connecting bore extending through the first closing device, which connects the cavity leading to the second discharge opening with the chamber of the housing, can be closed and opened very easily in this way. The adjusting arrangement used to adjust the second closing device may be the same adjusting arrangement that is used to adjust the first closing device. 
     As an alternative to the adjustment of the second closing device in its longitudinal direction, it is also possible that the second closing device can be rotated around its longitudinal axis by means of an adjusting arrangement for selectively closing and opening the connecting bore. The connecting bore can also be closed or opened in this way. 
     If, in a further advantageous embodiment of the invention, the adjusting arrangement comprises a control sleeve with at least one groove in which at least one pin connected to one of the closing devices engages, the control sleeve and the at least one closing device being rotatable relative to one another, a reliable possibility for actuating at least one of the closing devices results. In the case that both the first and the second closing device are adjustable in their longitudinal direction by means of the adjusting arrangement, the control sleeve may have separate grooves for both closing devices, which may have a similar design. However, the control sleeve can also be used to rotate the second closing device about its longitudinal axis. 
     A simple and reliable relative movement between the control sleeve and the at least one closing device results if the control sleeve and/or the at least one closing device can be rotated by means of a drive device which is operatively connected to the control sleeve and/or the at least one closing device via a transmission arrangement. 
     In another advantageous embodiment of the invention, the transmission arrangement may be a gear drive or belt drive. The control sleeve or at least one of the closing devices can be driven very easily by means of the drive device, for example by means of an electric motor, both by means of a belt drive and by means of a gear drive, whereby a particular advantage of a belt drive or a gear drive can be seen in its insensitivity to high temperatures. 
     Another advantageous embodiment of the invention may consist in that at least one of the closing devices is held in a non-rotatable manner. This prevents unwanted rotational movements of the at least one closing device, thus ensuring reliable operation of the apparatus. 
     A solution based on a method is evident from the features of claim  10 . 
     The method according to the invention, wherein the step of discharging the deformable material from the second discharge opening having a smaller cross-section is performed before the step of discharging the deformable material from the first discharge opening having a larger cross-section, makes it possible to expand or stiffen a structure previously formed by material discharged from the second discharge opening so that a high surface quality is present on the outer periphery of an object formed by the method according to the invention by the comparatively thin strands of the deformable material discharged from the second discharge opening, whereas the larger cross-section of the first discharge opening allows a large quantity of the deformable material to be discharged in a very short time, so that larger components can also be produced in a comparatively short time. 
     In particular, by discharging the deformable material from the first, larger discharge opening, an inner, stiffening area of the object to be produced, also known as infill, can be formed. In principle, the deformable material discharged from the second discharge opening forms a framework which is stiffened by the deformable material discharged from the first discharge opening. 
     The deformable material discharged from the first discharge opening can be introduced into the previously formed framework in the manner of a lattice structure, which leads to better stiffening of the object produced by the method according to the invention. Accordingly, this saves a considerable amount of time compared to known methods. The method according to the invention is particularly, but not exclusively, suitable for thin-walled components which have an internal volume formed by the deformable material discharged from the first discharge opening. 
     This also exploits the effect that the strands of the deformable material with a larger cross-section do not negatively affect the fine surface of the border formed from the strands of the deformable material with a smaller cross-section, but instead lie against the inside of the structure formed first. 
    
    
     
       Embodiment examples of the invention are schematically represented below with reference to the drawings. 
       In the drawings: 
         FIG. 1  shows an apparatus for producing three-dimensional objects from a deformable material; 
         FIG. 2  shows the apparatus of  FIG. 1  in a first configuration; 
         FIG. 3  shows the apparatus of  FIG. 1  in a second configuration; 
         FIG. 4  shows the apparatus of  FIG. 1  in a third configuration; 
         FIG. 5  shows a further embodiment of the apparatus for producing three-dimensional objects from a deformable material; 
         FIG. 6  shows the apparatus of  FIG. 5  in another configuration; 
         FIG. 7  shows an exemplary flow chart of a method for producing three-dimensional objects from a deformable material; 
         FIG. 8  shows three modes for performing the method for producing three-dimensional objects from a deformable material; 
         FIG. 9  shows a schematic view of an apparatus according to the invention in a first position; 
         FIG. 10  shows the apparatus of  FIG. 9  in a second position; 
         FIG. 11  shows the apparatus of  FIG. 9  in a third position; 
         FIG. 12  shows a more detailed view of the apparatus according to the invention in the position shown in  FIG. 9 ; 
         FIG. 13  shows a perspective view of a part of the apparatus of the invention as shown in  FIGS. 9 to 12 , and 
         FIG. 14  shows a top view of an alternative embodiment of a part of the apparatus according to the invention shown in  FIGS. 9 to 12 . 
     
    
    
       FIG. 1  shows an apparatus  1  for producing three-dimensional objects  2 . An exemplary three-dimensional object  2  is shown in  FIG. 8  in different modes of a method for producing the three-dimensional object  2 . 
     The apparatus  1  comprises a housing  3 , which serves to receive a deformable material  4 , from which, among other things, the three-dimensional object  2  can be produced. To feed the deformable material  4  to the housing  3  a feed device  5  is used, which may comprise, for example, an extruder not shown. The feed device  5  also comprises a feed line  6  which leads directly to the housing  3  and feeds the deformable material  4  to the housing  3 . For example, the deformable material  4  in the feed device  5  can be in the form of a solid granulate. In a manner not shown, the extruder can be connected to the print head or the housing  3  by means of a movable or flexible connecting hose, which may be designed in particular as a heating hose, in order to compensate for movements between these two elements. This results in a lower mass to be moved at the print head. 
     The deformable material  4  is discharged from the housing  3  through a first discharge opening  7 , which in this case is located at the bottom of the housing  3 . Furthermore, the apparatus  1  comprises a closing device  8  which serves to selectively close and open the first discharge opening  7  and which in the present case is designed in such a way that the cross-section of the first discharge opening  7  can be changed by means of the closing device  8  at least in several steps, in particular continuously. The variable cross-section of the first discharge opening  7  allows the web width and height of the individual layers of the deformable material  4  to be changed during printing. For example, the extrusion volume of the deformable material  4  discharged from the first discharge opening  7  can be up to 2 cm 3  per second, which is much higher than in known solutions, so that the three-dimensional object  2  can be produced in much less time. The above-mentioned extrusion volume is only an example. The apparatus  1  can be used for extremely small applications, e.g. at cellular level, as well as for extremely large applications, e.g. at ship or house building level, and for any applications in between. The size and of the apparatus and the possible extrusion volume are therefore correspondingly dimensioned. The first discharge opening  7  can have a round, oval, rectangular, polygonal or similar shape. In particular, free-form surfaces or shapes without any symmetry are also possible. 
     The area where the first discharge opening  7  is located may be a regular pyramid shape, for example with three or more corners, a cone or truncated cone, a hemisphere or a spherical tip. Irregular shapes of this area are also possible. 
     In the present case, the closing device  8  is a needle  8   a , which not only forms the closing device  8 , but also has a bore  9  extending through it in a longitudinal direction and through which the deformable material  4  or an additional material  10  can be passed. Preferably, the bore  9  has an inner diameter which substantially corresponds to the outer diameter of the additional material  10  or may be slightly larger. The bore  9  thus allows the additional material  10  to be embedded in the printing process. If the needle  8   a  forms the closing device  8 , this enables the formation of a very compact apparatus  1 , since in this case the needle  8   a  is not only used for discharging the additional material  10 , but also for closing the first discharge opening  7 , through which the deformable material  2  is discharged, thus eliminating the need for a large number of components. 
     The bore  9  inside the needle  8   a  can be concentric or non-concentric, i.e. off-center, inside the needle  8   a . There may also be two or more bores  9 , which can be arranged regularly or irregularly relative to each other. If several of the bores  9  are provided, several additional materials  10 , which may optionally be different, can also be discharged through the second discharge opening  11 . Furthermore, the bore  9  may be split in the longitudinal direction x or two or more bores may converge. 
     In the lower part of the needle  8   a  there is a second discharge opening  11 , which serves to discharge the additional material  10  from the needle  8   a . The additional material  10  is fed into the bore  9  of the needle  8   a  by means of a second feed device  12 , which in this case is located above the needle  8   a.    
     The second feed device  12  for the additional material  10  may comprise a suitable drive device, for example one or more piezo elements, a stepper motor or the like. For example, the second feed device  12  may have two counter-rotating rollers, with the additional material  10  lying between the rollers. Depending on the arrangement of the feed device  12 , these rollers can push or pull the additional material  10  into the bore  9  of the needle  8   a . The second feed device  12  can be located directly before the needle  8   a , directly after the needle  8   a , inside the needle  8   a  or elsewhere. Of course, the first feed device  5  could also be arranged differently with respect to the housing  3 . For example, the additional material  10  may be in wound form on a coil or the like associated with the second feed device  12 . 
     In the present case, the needle  8   a  is continuously movable in its longitudinal direction x in relation to the housing  3 , whereby the flow rate or the discharge volume of the deformable material  4  through the first discharge opening  7  is continuously variable and very precise control of the quantity of the deformable material  4  discharged through the first discharge opening  7  is possible. A corresponding drive or shifting device for moving the needle  8   a  in the longitudinal direction x is not shown in the figures. 
     Of course, in addition or as an alternative to the needle  8   a , other components can be used to change the cross-section of the first discharge opening  7 . The cross-section of the first discharge opening  7  can also be changed, for example, by replacing the area in which the first discharge opening  7  is located. If necessary, a template with different hole diameters may be located in this area, or a turret design is possible that has several of the first discharge openings  7 , each with a different cross-section. These holes or bores with different cross-sections forming the first discharge opening  7  can be arranged radially or linearly. Furthermore, in particular, continuously adjustable cross-sections of the first discharge opening  7  in the manner of an iris, a loop or spiral made of a temperature-resistant material, for example a metal band or thread, of Kapton, Kevlar or a high-temperature resistant silicone are possible. Another possibility is to create the constriction by radially arranged fingers, the distance between which is variable. Furthermore, it is possible to compress flexible material in the area of the first discharge opening  7 , which is designed similar to the connection mechanism of a bicycle pump and consists, for example, of silicone or a metal with nano-size pores. It is also possible to combine all the above-mentioned designs. 
     Furthermore, the apparatus  1  has a very schematically shown pressure generating device  13 , which serves to generate and control a pressure on the deformable material  4  located in the housing  3 . The pressure generating device  13  can be designed in a similar manner as a spring, whose force acting on the deformable material  4  is adjustable, however. The pressure generating device  13  for generating and controlling a pressure on the deformable material  4  located in the housing  3  results in a uniform discharge of the deformable material. 
     The pressure generating device  13 , which may also serve as a pressure reservoir, can be designed in many different ways. For example, it may be a mechanical pressure generating device  13  which may have one or more disk springs, spiral springs, wave springs, coil springs, volute springs, leaf springs, rubber dampers, rubber bands and any combination of the above elements. Furthermore, it may also be a pneumatic and/or hydraulic pressure generating device that works with positive or negative pressure, for example. An electromechanical design of the pressure generating device  13  is also conceivable. The pressure generating device  13  can also be included in the feed device  5 , e.g. in the form of a mechanically rotating screw that controls the volume within the housing  3  by changing the rotation speed. 
     For example, the volume within the housing  3  can be measured by means of a distance meter working according to an optical measuring principle and/or with ultrasound or with a hydraulic or pneumatic pressure sensor. It is also possible to generate a control system that can be adapted to the respective principle of the pressure generating device  13  and/or the feed device  5 . It can therefore work with the spring travel and an externally exerted pressure, a pneumatic or hydraulic pressure in a pressure chamber as well as an externally exerted pressure and/or a servomotor forming part of the pressure reservoir and an externally exerted pressure. 
     Furthermore,  FIG. 1  very schematically shows a separating device  14  for separating the additional material  10 . The separating device  14  may have one or more cutting edges, which may be flat, angular, scissor-shaped or round in the shape of a cigar cutter. The separating device  14  can be provided before the needle  8   a , after the needle  8   a  or in the needle  8   a . There may be one or more fixed cutting edges and one or more cutting edges moving relative to one another. Furthermore, two or more cutting edges moving relative to one another may be provided, such movement also being possible in two axes with respect to each other. Combinations of these are also conceivable. Separation of the additional material  10  by means of the separating device  14  is particularly useful or appropriate when switching from one of the modes described below for operating the apparatus  1  to another mode or when changing the position of the apparatus  1 . The separating device  14  can be controlled in such a way that the additional material  10  is fed or no longer fed during a subsequent mode change. The separating device  14  for separating the additional material  10  ensures flexible working when using the additional material  10 . 
     Generally, the additional material  10  can assume both technical and purely optical tasks. The additional material  10  is preferably a stiffening material, such as a thread of a strong or high-strength material, such as aramid, carbon, Kevlar or the like. The additional material  10  can also be made of a wide variety of materials, such as natural fibers, e.g. wood, stone dust, hemp fibers, cotton or the like; synthetic fibers, plastic filaments, glass fibers, electrical conductor materials, hoses, cannulas, organic or artificial fabrics, chemical or organic liquids, such as adhesives, and gases in any form. However, it is also possible to use a resin as the additional material  10 . 
     The additional material  10  preferably in the form of a fiber may be twisted, loose, fragmented or braided. It may be in the form of short, long and continuous fibers. The fiber can have a pre-embossed shape and can be spiral or folded, for example. Such a fiber can also be pre-treated, for example by soaking it in a liquid that hardens due to certain environmental influences. The liquid can also harden within the needle  8   a  or when leaving it. The fiber can be fused or sheathed with a matrix material. It is also possible to paint, polish, statically charge or compress the fiber which forms the additional material  10 . 
     In one embodiment, the additional material  10  could have a sheath of a flexible material, with the core of the thread located inside the sheath providing increased tensile strength even if the material of the sheath is damaged. Furthermore, the fiber or thread can limit the elongation of the flexible material of the sheath. In this context, a separate sheathing system for the fiber forming the additional material  10  is also conceivable. This system can be arranged immediately before the feed of the additional material  10  into the needle  8   a , or it can be placed elsewhere. 
     It is also possible to select the additive material  10  so that a chemical reaction with the deformable material  4  results to change the state of the deformable material  4  and/or of the additional material  10 . 
     The deformable material  4  may be any type of liquid that solidifies after exiting the first discharge opening  7  due to the temperature difference from the ambient temperature. Also, photochemical solidification or curing of the deformable material  4 , for example by irradiation with certain light sources or, if necessary, by ambient light is possible. Chemical curing or solidification is also possible through the reaction of two components that are located in the deformable material  4  or form the deformable material  4 . The deformable material  4  may also be a two-component material that cures under certain conditions. It is also conceivable that the deformable material can be cured by means of radiation at specific wavelengths, e.g. UV radiation. 
     Furthermore, a temperature control unit  15  is arranged around the housing  3 , allowing the deformable material  4  to be heated and/or cooled. In the present case, the temperature control unit  15  is connected to a temperature sensor  16 , which serves to measure a temperature of the deformable material  4 . The housing  3  can be provided with further temperature control devices, especially heating devices, in the area of the first discharge opening  7 . 
     In addition, a feedback valve  17 , which serves to return unneeded deformable material  4 , and a pressure sensor  18 , which is part of the pressure generating device  13  and facilitates the control or regulation of the pressure on the deformable material  4  located in the housing  3 , are arranged at the housing  3 . 
     The feedback valve  17 , which forms part of a recirculation system for the deformable material  4 , may be designed as a pressure relief valve to prevent damage to the entire apparatus  1  and in particular to the print head comprising the first discharge opening  7  and the second discharge opening  11 . For example, it could be a control valve with a recirculation channel, in which excess, deformable material is returned in liquid or solid form further up the process. However, a feedback line extending from the feedback valve  17  to the first feed device  5  is not shown in the figures. 
       FIGS. 2, 3 and 4  show different configurations or positions that can be assumed by the apparatus  1  and methods that can be performed with the apparatus  1 , which can also be described as different modes of the apparatus  1 . 
     In the configuration according to  FIG. 2 , the closing device  8  is in such a position that the first discharge opening  7  is open and the deformable material  4  is discharged to it. In this configuration, no additional material  10  is fed through the second discharge opening  11 . This can be achieved either by the second feed device  12  not conveying, or by the second discharge opening  11  being closed by a closing device not shown. 
     In the configuration of the apparatus  1  according to  FIG. 3 , however, the first discharge opening  7  is closed by means of the closing device  8  or the needle  8   a , so that no deformable material  4  is discharged. However, by means of the second feed device  12  not shown in  FIGS. 2 to 6 , the additional material  10  is fed through the hole  9  of the needle  8   a  and discharged through the second discharge opening  11 . 
     When the apparatus  1  is configured according to  FIG. 4 , the deformable material  4  is discharged through the at least partially opened first discharge opening  7  and the additional material  10  is discharged through the second discharge opening  11 . Due to the arrangement shown of the needle  8   a  within the housing  3 , the deformable material  4  surrounds the additional material  10 . 
       FIGS. 5 and 6  show an alternative embodiment of the apparatus  1  in two different configurations or positions. As described in more detail below, in the configuration of the apparatus  1  according to  FIG. 5 , three materials are discharged, whereas in the configuration of the apparatus  1  according to  FIG. 6  only one material is discharged. 
     In these embodiments, the diameter of the material dispensed through the first discharge opening  7  can also be changed gradually by arranging several of the needles, namely needle  8   a  as well as another needle  8   b  and, if necessary, further needles, which are not shown in  FIGS. 5 and 6 . This means that either the deformable material  4  can be discharged in different thicknesses, or different materials, namely a further deformable material  19 , in addition to the deformable material  4 , with in principle any number of sheaths, can be discharged, with the second needle  8   b  forming the wear device  8  in this case. The needles  8   a ,  8   b  and, if necessary, further needles can be moved individually in relation to each other and therefore any combination is possible regarding the discharge of the deformable material  4 , the additional material  10  and the further deformable material  19 . 
     Similar to the embodiment described above, the quantity of the discharged deformable material  4  and/or  19 , i.e. its flow rate, can also be controlled here by the position of the needles  8   a  and  8   b  by placing the needles  8   a  and/or  8   b  in different positions in their longitudinal directions x. 
     If only one material is to be discharged in different thicknesses, the walls of the inner needle  8   a  can be open or, as shown in  FIG. 6 , contain holes or openings  20 , allowing the deformable material  4  to flow into the needle  8   a  and/or  8   b , as shown in  FIG. 6 . 
     The apparatus  1  described above can be used very flexibly with the two discharge openings  7  and  11 , through which the deformable material  4  or the additional material  10  can be discharged. This makes it possible to discharge either only the deformable material  4 , only the additional material  10 , or the deformable material  4  and the additional material  10  simultaneously. In this way, the apparatus  1  can be used for a wide variety of tasks, including those which cannot be performed with known devices. This allows an extremely flexible use of the apparatus  1 , so that it can be used very beneficially. 
     A particular advantage of the apparatus  1  is that the cross-section of the discharge opening  7  for the deformable material  4  can be changed by the closing device  8 , thereby making it possible to change the quantity of material discharged within a specific time as well as the extrusion volume. This makes it possible, for example, to discharge large quantities of the deformable material  4  in order to produce relatively large objects  2  in a short time. In a possibly upstream step, finer surface structures can be generated. This is especially useful when details on the surface must be recognizable. Furthermore, this flexible use of the apparatus  1  makes it possible to produce objects  2  that require a higher surface quality. 
       FIG. 7  shows an exemplary flow chart of a method for the production of the three-dimensional object  2 , which is described in more detail below. Basically, in the method of producing the three-dimensional object  2  from the deformable material  4 , the deformable material  4  is discharged from the first discharge opening  7  of the housing  3  and the additional material  10  is discharged from the second discharge opening  11  of the needle  8   a . These two steps can be performed in different sequences, as described below. The process described below therefore provides for the discharge of both the deformable material  4  and the additional material  10 , so that a wide variety of tasks with regard to the production of three-dimensional objects  2  can be processed extremely flexibly. 
     For example, in a first step the deformable material  4  and in a second step the additional material  10  can be discharged to smooth and/or stiffen a structure formed by the deformable material  4 . In such a process, a comparatively large body or object can be formed in a relatively short time by means of the deformable material  4 , which can then be expanded and/or smoothed and/or stiffened by the additional material  10  by means of smaller surface structures. 
     Furthermore, or alternatively, it could be envisaged that in a first step the additional material  10  is discharged and that in a second step the deformable material  4  is discharged in order to expand a structure formed by the additional material  10 , for example to fill it. In this way, a rigid structure, e.g. a frame, can be created using the additional material  10 , which can then be expanded, e.g. filled, in a subsequent step with the deformable material  4 . 
     In order to be able to produce objects in a very short time and yet with a high surface quality, the deformable material  4  can be discharged in several steps in a further method. So, in a subsequent step, the first discharge opening  7  is opened with a considerably smaller cross-section than in a previous step. This is made possible by the closing device  8 , which can be adjusted at least in several steps, especially in an infinitely variable manner. 
       FIG. 8  shows the three different modes for performing the method described above. As can be seen, all modes are selectable independently of the previous printing mode, with the three-dimensional object  2  on the right-hand side being only an example, of course. One of the results is that the surface resolution of the three-dimensional object  2  was smoothed by the striped, small structures compared to the coarse structure. It is also evident that the coarse structure, with or without a core, may also be present on the surface. 
     The entire apparatus  1  can be arranged on a motion system. This may be a multi-axis robot arm, a gantry system, one or more rotary joints, one or more linear drives, such as mechanical spindles, hydraulic or pneumatic cylinders, a toothed belt, a cable, electromagnetic direct drives or the like, a roller system, a mobile base, a mobile table with corresponding linear and/or rotary axes, or a combination of several systems. If necessary, the apparatus  1  can also be placed on a flying object, such as a drone. 
       FIGS. 9 to 14  show inventive embodiments of the apparatus  1  for producing three-dimensional objects  2  from the deformable material  4 . The devices  1  described in  FIGS. 9 to 14  are partly similar, but partly also different from the embodiments of the apparatus  1  shown in  FIGS. 1 to 6 . Therefore, all the features of the apparatuses  1  according to  FIGS. 9 to 14  are described below. It is also possible to transfer certain features and properties of the apparatuses  1  shown in  FIGS. 1 to 6  to the apparatuses  1  shown in  FIGS. 9 to 14  and vice versa. In the following, identical components are identified by the reference numerals already used for the apparatuses  1  according to  FIGS. 1 to 6 . 
     The apparatus  1  has the housing  3 , which has a chamber  21  for receiving the deformable material  4  not shown in  FIGS. 9 to 14 . The deformable material  4  is fed via the feed line  6  into the chamber  21  of the housing  3  by means of the feed device  5 , which in this case is designed as an extruder. In the present case, the feed device  5  is designed in such a way that it assumes the function of the pressure generating device  13 , so that the latter is not required. Although chamber  21  is not referenced in  FIGS. 1 to 6 , it is of course also present there. The temperature control unit  15 , optionally comprising the temperature sensor  16 , can also be provided, but is not shown in  FIGS. 9 to 14 . 
     The deformable material  4  can be discharged from the chamber  21  of the housing  3  via the first discharge opening  7 , which is also present here. For selective closing and opening of the first discharge opening  7 , the closing device  8  is also used here, which will be referred to as first closing device  8  in the following. The first closing device  8 , similar to the closing device shown in  FIGS. 1 to 6 , is provided in the form of a needle. The first closing device  8  has a cavity  22  extending through it in the longitudinal direction x in the present case, said cavity  22  being connected via a connecting bore  23  to the chamber  21  of the housing  3 , which chamber  21  is arranged annularly around the first closing device  8 , and leading to the second discharge opening  11 . In this design, the cavity  22  tapers in the direction of the second discharge opening  11  in a step that is located above the connecting bore  23 . Such tapering is not absolutely necessary. The second discharge opening  11  is therefore a discharge opening provided in the first closing device  8 , which serves to discharge the deformable material  4  from the cavity  22  of the first closing device  8 . Accordingly, the deformable material  4  can be discharged alternatively to the first discharge opening  7  or the second discharge opening  11 . Furthermore, it is possible to discharge the deformable material  4  to both the first discharge opening  7  and the second discharge opening  11 . These different ways of configuring the apparatus  1  will be described in detail below. The second discharge opening  11  has a smaller cross-section than the first discharge opening  7 . In this case, the connecting bore  23  extends perpendicular to the cavity  22 , but this is not absolutely necessary. 
     The connecting bore  23  is similar to the holes or openings  20  in the walls of the inner needle  8   a  described above with reference to  FIG. 6 , or conversely, the function of the connecting bore  23  described here can be realized with the holes or openings  20  in the walls of the inner needle  8   a . The connecting bore  23  can also be regarded as the second feed device  12  according to the embodiment example of  FIG. 1 . However, the connecting bore  23  does not discharge the additional material  10  but the deformable material  4 . 
     The apparatus  1  also has a second closing device  24 , which serves to selectively close and open the connecting bore  23  and is located within the cavity  22  of the first closing device  8 . In this way, the supply of the deformable material  4  via the connecting bore  23  into the cavity  22  of the first closing device  8  can be interrupted so that the second discharge opening  11  can in principle be closed by means of the second closing device  24 . Similar to the first closing device  8 , the second closing device  24  is also in the form of a needle. 
       FIGS. 9, 10 and 11  show three different configurations or positions of the apparatus  1 . In the configuration of  FIG. 9 , the first discharge opening  7  is closed by means of the first closing device  8 . The second closing device  24  closes the connecting bore  23  and thus also the second discharge opening  11 . In this configuration, therefore, no deformable material  4  can emerge from the apparatus  1 . 
     In the configuration of  FIG. 10 , the first discharge opening  7  is closed by means of the first closing device  8  as shown in  FIG. 9 . In contrast, the connecting bore  23  is opened by the second closing device  24 , so that the deformable material  4  is discharged via the chamber  21  and the connecting bore  23  to the second discharge opening  11 . Since the second discharge opening  11  has a much smaller cross-section than the first discharge opening  7 , the deformable material  4  discharged accordingly has a very small cross-section or is very thin. 
     When the apparatus  1  is configured according to  FIG. 11 , both the first discharge opening  7  and the connecting bore  23  are open. This allows the deformable material  4  to be discharged through the first discharge opening  7 . The deformable material  4  can also be discharged through the connecting bore  23  to the second discharge opening  11 . However, since the first discharge opening  7  is also released, this portion of the deformable material  4  is less relevant or not relevant. 
     Preferably a method for producing the three-dimensional objects  2  from the deformable material  4  is performed by means of the apparatus  1 , said method comprising the following steps: a step of discharging the deformable material  4  from the first discharge opening  7  of the chamber  21  of the housing  3 ; a step of discharging the deformable material  4  from the second discharge opening  11  of the cavity  22 , which has a smaller cross-section than the first discharge opening  7 . The step of discharging the deformable material  4  from the second discharge opening  11  is performed before the step of discharging the deformable material  4  from the first discharge opening  7  of the housing  3  to expand and/or stiffen a structure formed by the deformable material  4  discharged from the second discharge opening  11  with the deformable material  4  discharged from the first discharge opening  7 . Of course, the apparatus  1  also allows to produce a three-dimensional object  2  as often as desired and in a different sequence of process steps. 
     In the embodiment example of the apparatus  1  shown in  FIGS. 9, 10 and 11 , the two closing devices  8  and  24  are adjustable in their longitudinal direction referred to as “x” by means of an adjusting arrangement  25 . For this purpose, the adjusting arrangement  25  in the embodiment example shown has a control sleeve  26 , which is also shown in  FIGS. 9, 10 and 11 . The control sleeve  26  in turn has two grooves  27  and  28 , one above the other in the present case, in which the respective pins  29  and  30  engage, which are each connected to one of the closing devices  8  or  24 . Here, the control sleeve  26  and at least one of the closing devices  8  and/or  24 , in the present case both closing devices  8  and  24 , are rotatable relative to each other. In the embodiment example shown, the pin  29  connected to the first closing device  8  engages in the lower groove  27  of the control sleeve  26 . The pin  30  connected to the second closing device  24  engages in the upper groove  28  of the control sleeve  26 . By means of the control sleeve  26  and the pins  29  and  30  engaging in the grooves  27  and  28 , the three positions of the two closing devices  8  and  24  shown in  FIGS. 9, 10 and 11  can be adjusted by positively guiding the pins  29  and  30  in the grooves  27  and  28 . This means that exactly one axial position of the closing devices  8  and  24  is assigned to each rotary position of the control sleeve  26 . So, in the embodiment example shown, the two closing devices  8  and  24  are not only positively guided by means of the control sleeve  26  but also coupled to each other via the control sleeve  26 . 
     The course of the two grooves  27  and  28  can best be seen in the position of the control sleeve  26  according to  FIG. 10 . This course of the grooves  27  and  28  ensures the described movement of the two closing devices  8  and  24 . It can be seen that for the transition from the state shown in  FIG. 9  to the state shown in  FIG. 10 , the groove  27  receiving the pin  29  connected to the first closing device  8  extends horizontally, which means that the first closing device  8  is not lifted when the control sleeve  26  rotates. Instead, only the second closing device  24  is raised, since the groove  28 , which receives the pin  30  connected to the second closing device  24 , is oblique. In the right-hand area of the control sleeve  26  shown in  FIG. 10 , the two grooves  27  and  28  are both oblique, which means that if the pins  29  and  30  are located in these areas, both the first closing device  8  and the second closing device  24  are lifted in the direction of their longitudinal axis x. The closing movement of the two closing devices  8  and  24  takes place in the opposite direction of these rotary movements, i.e. from the configuration of  FIG. 11  via the configuration of  FIG. 10  to the configuration of  FIG. 9 . 
       FIG. 12  shows a detailed view of an embodiment of the adjusting arrangement  25  for adjusting the two closing devices  8  and  24  of the apparatus  1 . It can be seen that the control sleeve  26  can be rotated by means of a drive device  32  which is operatively connected to the control sleeve  26  via a transmission arrangement  31 . In the present case, the transmission arrangement  31  is designed as a gear drive, but a belt drive or another suitable drive may also be provided. A direct drive through the drive device  32  is also conceivable. The drive device  32  may also be a pneumatic cylinder or a linear drive with a suitable transmission ratio. 
     The drive device  32  may be designed as an electric motor, for example. In the present case, the drive device  32  drives a gear  33 , which meshes with another gear  34 . The gear  34  in turn drives a housing  35  arranged inside it, which is firmly connected to the control sleeve  26 . In this way, the control sleeve  26  can be rotated about its longitudinal axis by means of the drive device  32 . The housing  35  serves to protect the control sleeve  26  with the grooves  27  and  28  as well as the pins  29  and  30  engaging in the grooves  27  and  28  of the control sleeve  26 . The housing  35  is rotatably mounted relative to another housing  36  of the adjusting arrangement  25  by means of two bearing devices  37 . 
     In order to ensure the movement of the first closing device  8  in its longitudinal direction x, i.e. in the vertical direction of the apparatus  1  shown in the figures, and to prevent rotation of the latter, the first closing device  8  is held in a non-rotatable manner. In the present case the first closing device  8  is held to the housing  3  of the apparatus  1 . The second closing device  24  is rotationally mounted on the housing  36  by a guide bearing  40 . In the present case, the closing device  8  is held in a non-rotatable manner by means of the sleeve  38 , whose outside is firmly connected to the housings  3  and/or  36  and whose inside has a non-circular cross-section which corresponds to the outer cross-section of the first closing device  8  in this area. For example, the sleeve  38  may have teeth, a polygon or the like on its inside, which ensures that the first closing device  8  is held in place or held in a non-rotatable manner. However, it would also be possible to mount the second closing device  24  in a non-rotating manner on the housing  36  by means of a corresponding sleeve  38 . Furthermore, the first closing device  8  of a construction similar to the guide bearing  40  could also be rotationally mounted on the housings  3  and/or  36 . This could require additional changes in the area of the two discharge openings  7  and  11 . 
     In contrast to the embodiment example of the apparatus  1  shown in  FIGS. 9 to 11 , the embodiment example of the apparatus  1  according to  FIG. 12  has a through hole bore  39  in the second closing device  24  through which the additional material  10  not shown can be passed. The bore  39  thus corresponds in principle to the bore  9  of the embodiment of the apparatus  1  as shown in  FIGS. 1 to 6 . The additional material  10 , which may have passed through the bore  39 , emerges in the area of the second discharge opening  11  and can be enveloped by the deformable material  4  discharged through the second discharge opening  11 . However, it is also possible to envelop the additional material  10  with the deformable material  4  discharged through the first discharge opening  7 . 
       FIG. 13  shows the control sleeve  26  with the two grooves  27  and  28  and the pins  29  and  30  engaging in these grooves in a perspective view. In the present case, two grooves  27  and  28  and two pins  29  and  30  are provided, but other numbers are also conceivable, such as three grooves  27  and  28  and three pins  29  and  30 . In contrast to the embodiment shown in  FIG. 13 , the grooves  27  and  28  can be connected continuously along the rotation direction of the control sleeve  26 . For example, the groove  27  may be a continuously closed guide that makes it possible to select any position of the closing device  8  by rotating the control sleeve  26  in one direction. This minimizes the control effort and reduces the pitch of the grooves  27  and  28 . 
     Contrary to the above description, an embodiment is also conceivable in which the control sleeve  26  is fixed and the closing devices  8  and  24  are rotated. These would then be positively guided in a similar way as described above by means of the pins  29  and  30  engaging in the grooves  27  and  28  of the control sleeve  26 , whereby the same or a similar movement of the closing devices  8  and  24  as described above could be achieved. Furthermore, the coupled movement of the two closing devices  8  and  24  by means of the adjusting arrangement  25  or the control sleeve  26  is not absolutely necessary. 
       FIG. 14  shows an alternative embodiment of the control sleeve  26 . One of the two closing devices  8  or  24  can be controlled in a manner similar or identical to the movement according to  FIGS. 9 to 13 . In contrast, the other of the closing devices  8  or  24  is moved from its closed position to its open position shown in  FIG. 14  by rotating it, thus opening the connecting bore  23 . For this purpose, one of the two closing devices  8  or  24  to be rotated can be driven by the drive device  32  of the adjusting arrangement  25 , if necessary without involving the control sleeve  26 . At least in the area of the connecting bore  23 , the driven one of the two closing devices  8  or  24  has a corresponding profile that allows the connecting bore  23  to be closed in one angular position and to be opened in another. 
     The apparatus  1  shown in  FIGS. 9 to 14  and described above is in principle scalable as desired. Moreover, further discharge openings and their associated closing devices can be provided, for example within the second closing device  24 . In addition, bores corresponding to the connecting bore  23  should then be provided in the closing devices.