WO2017005803A1 - 3d printing with a pasty, inhomogeneous printing material - Google Patents

Abstract

In the case of a method for carrying out 3D printing which uses a pumpable material mixture, which comprises pasty, inhomogeneous material, and in which the material mixture is discharged in the form of a strand of material (18) from a nozzle (11), and subsequently made to solidify, the invention proposes that a first pumpable, inhomogeneous component (23) is fed as a strand of material (18) to a mixing opening (12) and is passed through the mixing opening (12), a second pumpable component (24) is brought up to the strand of material (18) comprising the first component (23) from the outside in the region of the mixing opening (12), and the two components (23, 24) are subsequently passed through an outlet opening (14) of the nozzle (11), wherein the free cross section Q2 of the outlet opening (14) that allows material to pass through is smaller than the free cross section Q1 of the mixing opening (12) in such a way that the material mixture is squeezed with a so-called squeezing ratio Q1/Q2 > 1. The invention also proposes a device for carrying out the method.

Description

 "3D printing with a pasty, inhomogeneous printing material"

Description: The invention relates to a method for carrying out a 3D

Pressure.

From US 5,134,569 A a generic foreign method is known in which a polymer is conveyed to a nozzle and solidified by external treatment sources.

A generic method is known from practice: Here, an inhomogeneous, pasty, pumpable, mineral material is used in the form of concrete. Due to the mineral components with different grain sizes, this material is said to be inhomogeneous.

Solidification in the context of the present proposal is a hardening of the material strand that has escaped from the nozzle. Depending on the material used alone can cause the cooling such a solidification, z. B. in thermoplastic material. For mineral materials, the setting, z. As the above-mentioned concrete, cause the solidification. In polymer systems, crosslinking can cause the solidification. When processing pasty material, depending on the material used, the problem arises that the material solidifies sufficiently quickly. If, in order to create a three-dimensional body, the strand of material emerging from the nozzle of the printer does not solidify sufficiently quickly, it dissipates.

This problem is exacerbated when individual layers of the material strand are laid on top of each other and then the bottom layer must be so strong that it can safely carry the weight of the layers above it. Would the lower layers give way in such a way that their height is reduced, it would not be ensured that the emerging from the nozzle material strand can be stored as intended on the top layer. Rather, it may not be ruled out that the material strand from the nozzle hangs in the air in an undefined manner and is deposited somewhere on the drop, but not necessarily at the intended location.

If a material mixture is adjusted so that it solidifies very quickly, this is basically advantageous for the stability of the material strand discharged from the nozzle. However, unplanned service interruptions can cause the material mixture in the nozzle and in the nozzle upstream areas of the printing device solidifies, in which the material mixture is. Subsequently, a considerable amount of time consuming cleaning work is required to the

To make the printing device ready for use again. The usable for production time in which the printing device is ready for operation, their so-called availability, is thereby adversely affected.

The invention has for its object to improve a generic method to the effect that a paste SD printing multi-layer objects with fast construction progress and high component final strength is possible. Furthermore, the invention is based on the object, one for carrying out this Specify method suitable device, which has a high availability.

This object is achieved by a method according to claim 1 and an apparatus according to claim 13. Advantageous embodiments are specified in the subclaims.

In other words, the invention proposes that the mixing of the two components, of which one component can simplifyly be referred to as a "binder" and the other component as a "hardener", takes place only in the region of the nozzle, ie, shortly before the exit of the material strand from the nozzle. Thus, for the mechanism of solidification, a comparatively short, so-called pot-time can be used, that is to say a comparatively short period of time until the completion of the solidification process, for example by selecting the suitable composition of the two components. This rapid solidification ensures that a component with several superimposed layers can be created without the lower, in particular the lowest layer can deform undesirable.

The fact that the mixing takes place only in the region of the nozzle and not earlier, it is ensured that in case of disturbances in the process, if the device used for this must be stopped, so an interruption of the printing process, not in a large part of the printing device used both Components are present together and in a mix; Otherwise, in the case of an interruption in operation, this would mean that the material mixed from both components solidifies in the printing device. As a result laborious and time consuming cleaning would be required to free the used printing device from the solidified material and render it functional again. In order to enable the processing of pasty, inhomogeneous material, an intensive mixing of the two components in the region of the nozzle is provided according to the proposal. To effect this mixing, according to the proposal no moving mixing elements such as impellers o. The like. Required.

Rather, the mixture is due to a change in the geometry in the nozzle: the first component of the material to be processed first passes through a mixing opening. In the region of this mixing opening, the second component is supplied, ie either shortly before, or exactly in the mixing opening, or shortly after this mixing opening, the addition of the second component advantageously taking place in the mixing opening.

Downstream of the mixing opening, ie in the flow direction behind the mixing opening, the outlet opening of the nozzle is arranged, from which the entire material strand containing the first and the second component emerges from the nozzle. The outlet opening has a smaller free, the material passage cross-section than the upstream mixing opening of the nozzle, so that the material is literally squeezed at the transition from the mixing opening to the outlet opening.

The so-called squeezing ratio is determined by the ratio of the larger free cross section Q1 of the mixing opening to the free cross section Q2 of the outlet opening. By this squeezing ratio, which is greater than 1, an intensive mixing of the two components is ensured before they leave the outlet opening of the nozzle, so that subsequently the solidification of the material strand is ensured due to the intensive mixing of its two components.

Depending on the materials used, the solidification of the cladding layer can take place, for example, by light rays from the environment, or by atmospheric moisture, so that even before the

Two-component reaction and before completion of the solidification of the material strand, the cladding layer has sufficient strength to allow the deposition of another strand of material on the previously deposited layer of the material strand.

Advantageously, the mixing opening may have radially inwardly directed notches in the course of its circumference, that is, for example, a cross section which is contoured similar to a flower having a plurality of petals, or which is contoured similarly to a multi-beam star, or the like. The second pumpable component is introduced into these indentations. The subsequent squeezing of the material mixture up to its exit from the outlet nozzle causes the second component introduced into the indentations to be literally enclosed by the first component and thus penetrates deep into the interior of the entire material strand. Depending on the squeezing ratio and the pressure acting thereon on the material, a dendritic branching of the second component enclosed in the interior of the first component can take place. Such ramifications arise in particular because the material mixture of the two components is not homogeneous, but is designed inhomogeneous due to embedded particles. Particularly advantageously, the second component is introduced in each of the several existing notches to the first component in order to effect the most uniform possible mixing of the entire material strand. However, depending on the materials used, production of the printing device or its nozzle may be sufficient to provide only a single indentation or, in the case of multiple indentations, the second component only in the region of a single indentation on the surface first component, or at least not all the notches of the first component, if it turns out that for the material mixture used in each case sufficiently thorough mixing of the two components and thus a sufficiently rapid and complete solidification of the deposited from the nozzle strand of material can be ensured.

Advantageously, the strand of material dispensed from the nozzle is not solidified by a single solidification mechanism, but rather is solidified in a "duale" process.This "dualeye" process based on two different solidification mechanisms means that, on the one hand, a first solidification mechanism Through solidification of the discharged material from the nozzle strand causes, by means of two mutually reactive components. This first solidification mechanism may require a relatively longer period of time. Within a shorter time, ie, before the material strand is completely solidified, however, the strength of the material strand can be improved insofar as by means of a second solidification mechanism, an outer shell layer is solidified, so that a solid shell of the material strand is formed, the material strand a imparts increased load-bearing capacity and, prior to its solidification, makes it possible to deposit one or more further layers of material strands on this layer of the material strand. Similar to the wall of a pipeline, this outer, already solidified coating layer of the material strand ensures that mechanical stresses do not lead to deformation of the material strand before it is completely solidified and reaches its final mechanical load capacity.

In order to bring about the solidification of the outer coating layer in the context of this "dualeye" process, the material strand, which already contains both components, can be exposed from the outside to an influence which promotes solidification the envelope layer of the Material strand out. For example, this influence can be heat, so that a heating device can be provided downstream of the outlet opening, through which the material strand emerging from the outlet nozzle flows. Optionally, the outlet nozzle itself may also be heated in order to exert, in addition to the mixing-through effect, the influence which can be used on the material strand for the solidification of the coating layer.

As an alternative to heat, depending on the materials used, which are contained in the material strand, moisture may be released onto the surface of the strand of material, such as water or other reactive moisture, and as a third influence, an annular radiation source may be provided externally on the strand of material acts and thus promotes the solidification of an outer shell layer of the material strand.

Advantageously, it can be provided that the material mixture in the nozzle is tempered before the outlet opening by means of a heating device and is heated to a predetermined temperature. Regardless of the above-described influence to cause the solidification of a cladding layer, in this embodiment of the method, a temperature control of the material mixture is provided within the nozzle in order to influence the flowability of the material mixture advantageous. It can therefore be provided that within the nozzle, the material mixture is brought to a first, relatively low temperature in order to promote the flowability of the material mixture within the nozzle. In the region of the outlet opening or shortly after the outlet opening, the heating of the material mixture can be provided with a second, higher temperature, in contrast, in order to assist in the solidification of the aforementioned coating layer of the material strand. Advantageously, in the proposed method, the first, referred to as a binder component contain elastomer particles. The elastomer particles are configured as granules, that is, as irregularly shaped bodies, which are compared to uniform geometric bodies, such as. As beads, have the advantage to effect each other an improved mechanical support, so that components with relatively high mechanical strength can be created, which are very stable especially against pressure loads. For example, surfaces can be created that are walkable and can withstand traffic or sports loads. The elastomer granulate is present with different sized grains as a granule mixture. This also improves the mechanical strength of the finished product contained in the printer, and further reduces the free void volume of the granules by the granule mixture of grains of different sizes, which can be economically advantageous. For example, a mechanically comminuted recycled material can be used as granules, while otherwise the first component as binder can contain, for example, a polyurethane. Due to a reduced void volume of the elastomer granulate, accordingly, less polyurethane is required to achieve a certain volume of the first component, which is accordingly economically advantageous.

Advantageously, the first component can contain as elastomeric granules an EPDM granules. EPDM has excellent bonding properties, so that the layers superimposed on 3D printing can be reliably joined together and very stable, yet elastic components can be created, namely printed.

An application example of the proposed method is to process a strand of material containing EPDM granules to flat sheets, which then as a floor covering For example, for sports floors, raceways u. Like. Can be used. Due to the excellent adhesiveness color different areas can be permanently interconnected, so that, for example, dividing lines between different tracks, logos, or any alphanumeric markings can be easily introduced into the soil by first the desired labels are printed according to the proposed method and then be surrounded with the rest, pourable material of a different color, this free-flowing differently colored material is then crosslinked or solidified in a conventional manner.

In practical experiments it has proven to be advantageous to use in the first component granules with grain sizes between 0 and 1, 5 mm. The particular distribution of the different particle sizes in a granule mixture depends inter alia on the size reduction method used, so that an approximately Gaussian distribution of the granules over the different particle sizes will typically result. A granulate mixture between 0 and 1, 5 mm grain size can be processed, for example, with a printing device in which the outlet opening of the nozzle has a circular geometry and has a diameter of 3 mm. Depending on this nozzle diameter, strands of material can be deposited from the nozzle, which enable a comparatively high resolution of optical patterns in the area of the floor design. However, if other applications are pursued with the proposed method, for example, the production of weather-resistant elements for outdoor use, such as artificial stones o. The like. In the field of gardening or landscaping, so can nozzles with exceptionally large outlet openings are used and, accordingly, then Material mixtures in which the granulate mixtures have a different particle size range, For example, smaller grain sizes to create very precise and finely textured surfaces or larger grain sizes to achieve a faster construction progress, for example, to create essentially load-bearing structures that are either covered by other materials or should be arranged in a sufficiently large viewing distance that a accordingly fine elaborated Surface design is not required.

Advantageously, it can be provided that the first component is conveyed by means of an extruder before it enters the mixing opening. Due to the fact that this first component, which is indeed inhomogeneous and contains the granules, is conveyed by means of an extruder, it is subjected to mechanical action, so that on the one hand it undergoes a kind of pre-compaction by arranging the individual granules of the granulate mixture as close as possible mentioned above, the smallest possible void volume of the granule mixture cause. Secondly, the grains of the granular mixture are brought into a kind of preferred orientation, so that the subsequent passage of the material mixture through the nozzle and its mixing and outlet openings is favored. With regard to the material flow of the first component is also noted that when using elastomeric granules, the fine grain fractions act as a flow improver, which make pumping the first component either possible or at least possible with a lower energy input.

In first practical experiments, it has been found that the proposed method can advantageously be carried out with materials in which a urethane acrylate or urethane methacrylate is combined with isocyanate reagents in the material mixture. On the one hand, these materials enable reliable solidification in favor of a high stability and, on the other hand, a fast initial strength can be achieved. Tels a solidified shell layer, so that with the proposed method and using these materials within a relatively short time, a comparatively large volume of material can be constructed, with the large volume of material is not meant the volume, which occupies the body produced with its envelope contour, but rather, the volume of material dispensed from the printer. This ability to build up a large volume in a short time means fast work progress and consequently low production times for the objects to be printed.

In order to influence the process, at least one additional material which originates from the group of the following materials may advantageously be used in the material mixture: A reactive diluent may be used, for example consisting of mono-, di-, tri- or polyfunctional acrylates which corresponds to urethane or urethane meth acrylate can be added to affect its viscosity. Advantageously, a viscosity of less than 10,000 mPas is set, so that the corresponding, pasty material mixture is easily pumped. The material mixture may have a photoinitiator to enable solidification by means of light radiation, for example to obtain the outer cladding layer, by correspondingly irradiating the material strand with light or exposing it to ambient light. Advantageously, an inhibitor can be used to influence the pot life of the solidification reaction of the two components and to prevent premature solidification of the material strand. Rheological auxiliaries can be added to the material mixture in order to influence the flow properties of the two components or of the entire material mixture, be it within the printing device, for example within the nozzle, in order to optimally adjust the material there, or if it is as fluid as possible around the material einzustel- len, when it has escaped from the nozzle and then, after filing on possibly a previous position, should not flow.

For carrying out the proposed method can advantageously be used a device whose nozzle has a nozzle channel through which flows the Mate almischung. The nozzle channel leads the material mixture first to the aforementioned mixing opening and then to the outlet opening of the nozzle. In the region of the mixing opening, this nozzle has at least one feed channel, so that here a second component can be supplied to the first component, which passes through the mixing opening. In this case, the mixing opening has a free cross section, designated Q1, which designates the area in the mixing opening through which material can flow through the mixing opening. The outlet opening downstream of the mixing opening has a free cross-section, designated Q2, which is less than the free cross-section Q1 of the mixing opening, in order in this way to produce the abovementioned squeezing effect and thus the mixing of the two components.

The mixing opening may advantageously have the above-mentioned notches in the course of its circumference, so that the material flow of the first component passing through this mixing opening also has such a notch in cross-section. In this notch of the mixing opening of the supply channel opens, in this way to allow the introduction of the second component as deep as possible in the cross section of the first component and thus to support a very intensive mixing of the two components.

Depending on which material is to be processed, the nozzle may advantageously have a heater, so that the nozzle channel through which the material mixture flows can be tempered at a predetermined temperature. For example, besides the above-mentioned elastomeric granules, too mineral constituents are present in the first or second component, or metallic or natural chips, for example wood chips, can be processed as constituents of the first component if the printed components are to have the corresponding optical or also mechanical properties.

In one embodiment of the device can be advantageously provided that in the flow direction behind the outlet opening of the nozzle an annular radiation source is arranged, which surrounds the emerging from the nozzle strand of material, and the jets are directed radially inward, namely on the strand of material. In this way, a radiation-assisted solidification of the outer shell layer of the material strand can be effected.

Alternatively, or in addition to the above-mentioned annular radiation source, a heater can be arranged downstream of the outlet opening in the flow direction, so that the creation of the outer one by means of a corresponding heat effect

Covering layer can be supported, depending on which materials are present in the material strand and which influences accordingly favor the solidification of an outer shell layer.

Advantageously, a friction-reducing surface coating can be provided inside the nozzle, for example made of PTFE, in this way especially where the first component flows, or where the second component flows, or where both components or the material mixture prepared from two components, the nozzle flows through, reduce the wall friction resistance and to support a low-resistance, easy flow through the nozzle.

The invention will be explained in more detail below with reference to the purely schematic illustrations. It shows

1 is a perspective view of an apparatus for performing a 3D paste printing method,

2 shows two cross sections through a nozzle which can be used in the device of FIG. 1,

 3 shows a cross section through a nozzle with a to FIG.

 FIG. 4 shows a view similar to FIG. 2, but for a further alternative embodiment of a nozzle, and FIG

Fig. 5 is a schematic, greatly simplified, perspective view of a nozzle. In Fig. 1, 1 denotes a device as a whole, which serves to deposit pasty, inhomogeneous material in the 3D printing process in layers.

A liquid A, for example a polyurethane, and a solid B, for example an EPDM granulate, are each fed to a mixer 2 and mixed there with one another. Together they form a first component 23 of the paste strand to be printed in the SD printing process. If appropriate, the first component 23 may also contain additives which are added in the mixer 2 or later to the two constituents of the first component 23 mentioned above. The first component 23 is conveyed by means of a feed pump 3 through a transport line 4, wherein in Fig. 1 right schematically a section of the first component 23 is shown, which is located in the transport line 4. Granulate 22 with different sized EPDM grains is surrounded by the liquid A. The transport line 4 can be heated in order to ensure optimum flow properties of the first component 23. For this purpose, a pipe heater 5 is schematically indicated, which surrounds the transport line 4 on a small portion of the transport line 4. The first component 23 passes into a buffer container 6, which serves to equalize the material flow and has a filling sensor 7 indicated schematically. The fill sensor 7 can monitor the fill level within the buffer tank 6 in a first embodiment; In this case, the supply pump 3 is turned on when it falls below a minimum level or increases their speed, and when exceeding a maximum level in the buffer tank 6, the feed pump 3 is turned off or reduced their speed. The filling sensor 7 may be configured in a second embodiment as a pressure sensor which detects the pressure within the buffer tank 6; In this case, the supply pump 3 is switched on or falls below a minimum pressure, the speed increases, and when exceeding a maximum allowable pressure in the buffer tank 6, the feed pump 3 is turned off or reduced their speed. The design of the filling sensor 7 as a pressure sensor has the advantage that the buffer container 6 is always completely filled and is thus avoided that air bubbles enter the material.

The buffer container 6 is followed by a metering screw 8 which is rotated by a drive motor 9 and extends from the buffer container 6 into a nozzle channel 10 of a nozzle 11. The metering screw 8 runs conically, so that it intensively processes and compresses the material transported by it, thereby aligning the solids content of the first component 23 in the manner of a preferred orientation, which improves the flow properties of the first component 23. The metering screw 8 extends until just before a mixing opening 12 which is disposed within the nozzle 1 1. In FIGS. 2-4, a mixing opening 12 is shown in each case, and downstream of the mixing opening 12, an outlet opening 14 of the nozzle 11 which can be seen from FIGS. 2 and 4 is arranged in the flow direction. By means of a feed channel 15 and a pump 16, a second liquid H can be introduced into the nozzle 1 1 in the region of the mixing opening 12. While the first fluid A may be referred to simply as a "binder", the second fluid H may also be referred to as a "hardener" to simplify matters, so as to express that the two fluids A and H react with one another and solidify cause the material mixture, which contains the first liquid A, the solid B, the second liquid H and optionally additives such as a reactive diluent, a photoinitiator, an inhibitor or theological aid. The second liquid H therefore constitutes a second component 24, so that the material mixture to be printed out consists of these two components 23 and 24. The additives may be contained exclusively in the first component 23 or exclusively in the second component 24, or may be distributed to both components 23 and 24.

A pneumatic switch 17 serves to switch the addition of the second component 24 in the nozzle 1 1 on or off, so that, for example, only hardener or the second component 24 flows into the nozzle 1 1 when it moves and deposits a strand of material, that is, when the first component 23 flows through the nozzle 1 1.

In the illustrated embodiment, the nozzle 1 1 is moved in the direction of the arrow R, so that a strand of material 18, which contains the entire material mixture of the two components 23 and 24, emerges from an outlet opening 14 of the nozzle 1 1, comes down and there a substrate 19 is deposited. An already deposited part of this strand of material 18 can be seen lying left of the nozzle 1 1 on the substrate 19.

1, a device 20 is further indicated in the region of the outlet opening 14, which surrounds the material strand 18 in an annular manner and is annular on the material strand 18 from the outside. acts. The device 20 serves to bring an outer shell layer of the material strand 18 to solidification before the reaction of the two components 23 and 24 can durcherstarren the material strand 18 over its entire cross-section. The device 20 is indicated purely schematically in FIG. 1: it can be an integral part of the nozzle 11 and surround the outlet opening 14. For example, the outlet opening 14 may be heated when the heat causes the solidification of a cladding layer of the material strand 18. However, the device 20 may also be connected downstream of the nozzle 1 1, viewed in the flow direction of the material strand 18, and for example retrofitted to the nozzle 1 1 or be arranged independently of the nozzle 1 1 just behind the outlet opening 14. The course of the material strand 18 is shown purely schematically, it has been found in practical experiments to be advantageous that the material strand 18 is discharged from the outlet opening 14 or from the device 20 at a height above the substrate which is approximately half the diameter of the outlet opening 14 equivalent.

Apart from the exemplary embodiment of the device 20 as a heater, the device 20, depending on the materials that form the material strand 18, and depending on the curing mechanisms, be configured as a radiation device, which irradiates, for example, UV rays annular from the outside onto the strand of material 18 or the device 20 can serve to apply a liquid from the outside onto the strand of material 18, for example water or another hardening liquid, by sprinkling or by means of small spray nozzles.

2 shows two cross sections through the nozzle 1 1 in order to clarify the size ratios of the two different openings. In FIG. 2, a mixing opening 12 is shown on the left. An arrow schematically illustrates the material flow of the two Components 23 and 24 to a Austhttsöffnung 14, which is shown in Fig. 2 right.

Within a cylindrical housing of the nozzle 1 1, the mixing port 12 is located with a diameter Q1. Due to the corresponding inner contour of the mixing opening 12, this has a plurality of notches 21. A strand of pasty material of the first component 23, which flows through this inner contour of the mixing opening 12, accordingly has an outer contour with such indentations. Around this inner contour of the mixing opening 12, another section of the mixing opening 12 extends with a circular outer contour. For example, in the flow direction of the material mixture, the inner contour of the mixing opening 12 can widen from the contour provided with the notches 21 to the circular contour, so that in this widened area the mixing opening 12 has an annular feed channel 15. The feed channel 15 is circular outside, filled with the second component 24, and bounded inwardly by the provided with the many notches material strand of the first component 23, which emerges from the petal-like contour of the mixing port 12.

In the further course of the nozzle 1 1, this material mixture, consisting of the interior, petal-like strand of the first component 23 and the supplied through the feed channel 15 second component 24 passes into the outlet opening 14. This has a circular cross section with the diameter Q2, The size ratio Q1 / Q2 results in a squeezing ratio whose value is greater than 1 and which apart from the geometric shaping and contouring of the mixing opening 12 is a measure of the intensity of the mixing of the two components 23 and 24 represents the material mixture. 3 shows a second embodiment of a mixing opening 12. Again, the petal-like geometry of the mixing opening 12 for the first component 23 is provided as in FIG. 2. However, a single, annular feed channel 15 does not run around the entire mixing opening 12, but each notch 21 is associated with its own feed channel 15, which leads the second component 24 into the respective notch 21 of the mixing opening 12, and thus into the respective notch of the paste strand of the first component 23rd

Fig. 4 shows cross-sections through a further embodiment of a nozzle 1 1. Similar to FIG. 2, the material flow from the mixing opening 12 to the outlet opening 14 is also indicated here by an arrow. The embodiment of FIG. 4 is provided for processing a granule mixture with larger grain diameters than in the embodiment of FIG. 2, therefore the values Q1 for the mixing opening 12 and Q2 for the outlet opening 14 are each larger than in the embodiment of FIG As shown in FIG. 4 results in a squeezing ratio whose value is greater than 1, since the diameter Q2 of the outlet opening 14 is smaller than the diameter Q1 of the mixing opening 12. Purely by way of example, the mixing opening 12 in turn notches 21, but they have a has a rectilinear and non-rounded inner contour and therefore not similar to a petal, but is contoured much like a star.

Based on Fig. 5, the position of the mixing port 12 and the outlet opening 14 within the nozzle 1 1 is indicated. Both openings are punctured and indicated purely schematically, without their respective inner contour. Already on the basis of the outer contour of the nozzle 11, it can be seen that its cross-section decreases from the region where the mixing opening 12 is arranged towards the end of the nozzle 11, where the outlet opening 14 is arranged. In the embodiment shown in Fig. 5, the supply of the second component 24 by feed channels 15, of which only two pieces are shown, initially axially parallel through the wall of the nozzle 1 1 to the mixing port 12. Only there do the feed channels 15 open into the mixing port 12. Alternatively to the illustrated course of the feed channels 15, 12 transverse bores can extend radially through the wall of the nozzle 1 1 at the outside of the nozzle 1 1 at the level of the mixing opening. These transverse bores may form the feed channels 15 or at least a portion of the respective feed channel 15.

Claims

Method for performing 3D printing, wherein a pumpable material mixture is used which contains pasty, inhomogeneous material, and the material mixture in the form of a strand of material (18) from a nozzle (1 1) is output and then solidified, characterized, a first pumpable, inhomogeneous component (23) is fed as material strand (18) to a mixing opening (12) and passed through the mixing opening (12), in the area of the mixing opening (12) a second pumpable component (24) from the outside to the the first component (23) containing material strand (18) is introduced, and then both components (23, 24) through an outlet opening (14) of the nozzle (1 1) are guided, wherein the material passage permitting a free cross-section Q2 of the outlet opening (14 ) is smaller than the free cross-section Q1 of the mixing opening (12), such that the material mixture is squeezed with a so-called crush ratio Q1 / Q2> 1. Method according to claim 1, characterized, the mixing opening (12) has notches (21) directed radially inwards over its circumference and the second pumpable component (24) in these notches (21) is guided towards the material strand (18) containing the first component (23). Method according to claim 1 or 2, characterized, that the material strand (18) containing the first component (23) and the second component (24) is in a "dual your "process is petrified, wherein first an outer shell layer of the material strand (18) is solidified and later the material strand (18) is brought to the interior to solidification. Method according to claim 3, characterized, in that the material strand (18) containing the two components (23, 24) is externally exposed to a solidification-promoting influence to solidify the outer shell layer of the material strand (18), the influence being selected from the group of the following influences:  - heat,  - Humidity,  - radiation. Method according to one of the preceding claims, characterized the material mixture in the nozzle (11) is tempered in front of the outlet opening (14) by means of a device (20) designed as a heating device and heated to a predetermined temperature. Method according to one of the preceding claims, characterized in that a first component (23) containing granules (22) of elastomer particles with differently sized grains is used. Method according to claim 6, characterized, the first component (23) contains an EPDM granulate (22). 8. The method according to claim 6 or 7,  characterized,  that the granules (22) grains with grain sizes between 0 and 1, 5 mm. 9. Method according to one of the preceding claims, characterized in that  in that a first component (23) is used which contains polyurethane as the liquid (A). 10. The method according to any one of the preceding claims, characterized  in that the first component (23) is conveyed by means of a metering screw (8) before it enters the mixing opening (12). 1 1. Method according to one of the preceding claims, characterized  in the material mixture, a urethane acrylate or urethane methacrylate is combined with an isocyanate reagent. 12. The method according to any one of the preceding claims, characterized  in that at least one material from the group of the following materials is used in the material mixture: - reactive diluents,  - photoinitiator,  - inhibitor,  - theological tool. 13. An apparatus for carrying out the method according to one of claims 1 to 12,  with a nozzle (1 1), which one of the material mixture flowed through to the mixing port (12) and the Outlet opening (14) of the nozzle (1 1) leading to the nozzle channel (10), and in the region of the mixing opening (12) at least one feed channel (15) is arranged, through which a second pumpable component (24) to the mixing opening (12) passing first component (23) can be supplied, wherein the mixing opening (12) has a free having a material passage enabling cross-section Q1, and wherein in the flow direction behind the mixing opening (12) the outlet opening (14) is arranged, which has a free, a material passage enabling cross-section Q2, which is less than the free cross-section Q1 of the mixing opening (12) , Device according to claim 13, characterized, that the mixing opening (12) has at least one radially inwardly directed notch (21) in the course of its circumference and the feed channel (15) opens into this notch (21). Apparatus according to claim 13 or 14, characterized, in that the nozzle (1 1) is heated, such that the nozzle channel (10) can be tempered at a predetermined temperature. Device according to one of claims 13 to 15, characterized, that in the flow direction behind the outlet opening (14) of the nozzle (1 1) an annular, the material strand (18) surrounding, configured as a radiation source means (20) is arranged, whose jets are directed radially inwards, on the strand of material (18) , Device according to one of claims 13 to 16, characterized, in the flow direction behind the outlet opening (14) the nozzle (1 1) an annular, the material strand (18) surrounding configured as a heater means (20) is arranged such that the heat emitted by the heater is directed radially inwards, on the strand of material (18). 18. Device according to one of claims 13 to 17,  characterized,  in that the nozzle (11) has at its first component (23) and / or the second component (24) and / or both Component (23, 24) containing material strand (18) leading inner surface having a friction-reducing surface coating. Device according to claim 18,  characterized,  the surface coating contains PTFE.