3D concrete print head
The 3D concrete print head ensures homogeneous mixing by pre-mixing additives with raw materials in the supply line, resulting in improved mixing quality and a more compact, efficient design suitable for additive incorporation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- MAI INT
- Filing Date
- 2022-10-20
- Publication Date
- 2026-04-20
AI Technical Summary
Existing 3D concrete printing heads face challenges in ensuring homogeneous mixing of materials and require a more compact and lightweight design for efficient operation, particularly when incorporating additives like curing accelerators or rheological modifiers.
The 3D concrete print head design allows additives to mix with concrete or mortar raw materials upstream of the mixing chamber, using an additive line that opens into the material supply line, potentially with multiple channels and flow enhancements like nozzles or static mixers, to ensure thorough mixing before entering the mixing chamber.
This design achieves better mixing quality and a more compact, lightweight print head, enhancing operational efficiency and adaptability to various material properties.
Smart Images
Figure 2026512621000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a 3D concrete printing head for two-component or multi-component materials. Materials that can be processed with such a 3D concrete printing head can be concrete, mortar or geopolymers and mixtures of these materials. For example, pre-mixed dry mortar in a factory can be used, and this dry mortar may contain geopolymers. Therefore, the expression "3D concrete printing head" used within the scope of the context of this specification should not be understood to mean that only concrete can be processed with a 3D concrete printing head. Rather, this expression should be understood to mean including the processing of the materials described above.
Background Art
[0002] A 3D concrete printing head needs to continuously feed out a sufficiently mixed two-component or multi-component material in order to ensure homogeneous material properties of the material fed out by the 3D concrete printing head. Otherwise, there is a risk that the components produced by 3D concrete printing processing may irregularly exhibit different material properties depending on the location. Furthermore, the 3D concrete printing head should be as compact and lightweight as possible so that it can be moved quickly and accurately, especially swiveled, for example by a robotic arm.
[0003] In order to achieve the desired properties of the material fed out by the 3D concrete printing head, additives are usually added to the concrete or mortar etc. that forms the material base of the material. Depending on the desired material properties, a plurality of additives may be used. Such additives are, for example, curing accelerators or inhibitors, coloring pigments, and / or substances that affect the rheological properties of the material to be processed. Such substances may be so-called plasticizers that change the thixotropy of the material to be processed, or flow aids that enhance the fluidity of the material mixture.
[0004] Regardless of the exact properties of the additives used, in a 3D concrete printhead, it is crucial to thoroughly mix the additives with the concrete or mortar that forms the material base before the material is dispensed as a whole from the 3D concrete printhead. DE 10 2020 003 760 A1 discloses a 3D concrete printhead that seeks to ensure that the concrete or mortar raw materials are homogeneously mixed with the additives used within the mixing chamber of the 3D concrete printhead by introducing the concrete or mortar raw materials and additives or multiple additives into the mixing chamber simultaneously but separately from each other through a common opening in the perimeter wall of the mixing chamber. This makes the entire length of the mixing chamber available for homogeneous mixing of the materials introduced into the mixing chamber. [Overview of the project] [Problems that the invention aims to solve]
[0005] The fundamental objective of this invention is to ensure homogeneous mixing of the materials used and to provide a 3D concrete print head with a simpler structure than the 3D concrete print head known from DE 10 2020 003 760 A1. [Means for solving the problem]
[0006] Building upon the prior art described above, this objective is achieved according to the present invention by a 3D concrete print head having the features of claim 1. The 3D concrete print head according to the present invention is designed to allow the concrete or mortar raw materials and additives to be used to come into contact with each other and be mixed before entering the mixing chamber. To achieve this, an additive line, whose end is located on a material supply line leading to the mixing chamber, opens to the material supply line through an additive opening, the additive opening being located upstream of the material supply opening where the material supply line opens to the mixing chamber. Thus, the additive opening is not located on the material supply opening in the periphery wall of the mixing chamber as in the prior art described above, but is set back into the material supply line, thereby separating it from the housing wall of the mixing chamber. The distance of the additive opening from the housing wall or material supply opening should be at least approximately equal to the diameter of the material supply opening, but may be significantly larger. By significantly reducing the volume of the material supply line relative to the mixing chamber, better and faster mixing of concrete or mortar raw materials and additives or multiple additives in the material supply line becomes possible, and thus, the length of the mixing chamber can be shortened compared to the prior art while maintaining the same diameter. Within the context of the objectives to be achieved, this results in a 3D concrete print head that is more compact and lighter, which can result in better mixing quality despite its more compact structure.
[0007] The additive line may be made of, for example, a metal or plastic material. Preferably, the additive line, especially its ends, is provided with a lining to prevent material buildup. Such a lining may be made of, for example, polytetrafluoroethylene (Teflon®). If the entire additive line or at least its ends are made of such friction-reducing material, lining of the additive line or its ends is not required. To increase the flow rate of the additive into the material supply line, thereby achieving better initial mixing of the additive with the material already flowing in the material supply line, the ends of the additive line may further be in the form of a nozzle or may be provided with a nozzle.
[0008] According to one embodiment of the 3D concrete print head of the present invention, the additive line may have two or more channels, each opening into the material supply line through a corresponding additive opening. This allows two or more additives to be fed into the material supply line by a single additive line. Whether the additive line has only one channel or multiple channels, the ends of the additive line are preferably arranged concentrically with the material supply line, that is, the cross-sections of the material supply line and the additive line have a common center.
[0009] Regardless of whether the end of the additive line is concentric with the material supply line or not, the end of the additive line can be mounted to be axially displaceable, thereby allowing the distance from the housing wall of the mixing chamber to the additive opening (or multiple additive openings if multiple channels are present in the additive line) to be varied. This allows the portion of the material supply line available for mixing and homogenization before inflow into the mixing chamber to be made longer or shorter, thereby adapting to the mixing characteristics of the additive used.
[0010] To improve mixing quality even when the portion available for mixing and homogenization in the material supply line is very short, in some embodiments of the 3D print head according to the present invention, a flow cross-section constriction is present in the material supply line downstream of the additive opening and upstream of the material supply opening. Such a flow cross-section constriction may particularly take the form of a Laval nozzle. The flow cross-section constriction locally increases the flow velocity in the material supply line, thereby resulting in more thorough mixing of the concrete or mortar raw materials and additives in the material supply line. Alternatively, or in addition to the above, a static mixer may be present in the material supply line downstream of the additive opening and upstream of the material supply opening, which similarly further thoroughly mixes the additives and concrete or mortar raw materials in the material supply line.
[0011] As previously explained, an additive line may have two or more channels to allow multiple additives to be fed into the material supply line. Alternatively, or in addition to this, multiple additive lines, each with an end located in the material supply line, may be arranged such that their additive openings open into the material supply line. Multiple additive lines may open into the material supply line at the same point when viewed in the flow direction of the material supply line. The ends of multiple additive lines may be axially positioned in the material supply line or project radially into the material supply line, and may be offset from each other in the circumferential direction of the material supply line. For example, the ends of multiple additive lines may project radially into the material supply line such that their additive openings are located near the center of the material supply line. In this case, all additives fed into the material supply line through such additive lines will merge in the core region of the flow through the material supply line, thereby mixing thoroughly with each other and with the concrete or mortar raw materials flowing into the material supply line immediately after they are fed in.
[0012] Alternatively, the ends of multiple additive lines may project tangentially into the material supply line, and they may also be offset from one another in the circumferential direction of the material supply line. By feeding the additives tangentially into the material supply line in this way, a vortex action can be imparted to the flow in the material supply line, which enhances mixing and thereby improves the quality of the mixture. Embodiments are also possible in which some ends of the multiple additive lines project radially into the material supply line, and the other ends of the multiple additive lines project tangentially into the material supply line.
[0013] Depending on the characteristics of the additives used, it may be advantageous not to feed those additives, or all of the additives, into the material supply line at the same point when viewed in the flow direction of the material supply line. This is the case, for example, when some additives are not easily miscible with each other and therefore must be mixed individually with the concrete or raw materials first. To achieve this goal, some embodiments of the 3D concrete print head according to the present invention are distinguished in that the additive openings of the multiple additive lines are arranged one behind the other when viewed in the flow direction of the material supply line. Thus, the additive openings of the multiple additive lines are axially separated from each other in the material supply line. As already described above, the ends of the multiple additive lines may project radially or tangentially into the material supply line, and preferably may be offset from each other in the circumferential direction of the material supply line.
[0014] In another embodiment of the 3D concrete print head according to the present invention having multiple additive lines, the ends of the multiple additive lines are arranged axially and front to back in the material supply line. Thus, it is also achieved that the additive openings of the multiple additive lines are axially separated from each other in the material supply line. In the last embodiment described, a static mixer or flow cross-section constrictor may be present between two additive openings of the multiple additive lines to enhance the mixing and homogenization process and thereby improve the mixing quality, the additive openings being continuous along the flow direction of the material supply line. As already described, the flow cross-section constrictor may have the form of a Laval nozzle in particular.
[0015] The 3D concrete print head configuration according to the present invention can be specifically adapted to any intended use and any combination of materials to be processed, due to its numerous possible modifications. In addition, the 3D concrete print head according to the present invention in any embodiment ensures excellent mixing and homogenization of the materials used, and is very easy to handle due to its compact and lighter structure, which in particular reduces the requirements for handling robots.
[0016] Embodiments of the 3D concrete print head according to the present invention will be described in more detail below with reference to illustrative schematic drawings. [Brief explanation of the drawing]
[0017] [Figure 1] This shows a partial longitudinal section of a first embodiment of the 3D concrete print head according to the present invention. [Figure 1a] Figure 1 shows a cross-sectional view AA, which has an additive line arranged concentrically with the material supply line and has a single channel. [Figure 1b] Figure 1 shows a cross-sectional view AA, which has two channels and an additive line arranged concentrically with the material supply line. [Figure 1c]Fig. A-A cross-sectional view of Fig. 1 shows three additive lines that are offset in the circumferential direction and project radially into the material supply line. [Figure 1d] Fig. A-A cross-sectional view of Fig. 1 shows two additive lines that are arranged on opposite sides of each other and project radially into the material supply line. [Figure 1e] Fig. A-A cross-sectional view of Fig. 1 shows two additive lines that are arranged on opposite sides of each other and project tangentially into the material supply line. [Figure 2] Fig. shows a detailed view of a modification of the embodiment shown in Fig. 1. [Figure 3] Fig. shows a detailed view of a further modification of the embodiment shown in Fig. 1. [Figure 4] Fig. shows a partial longitudinal sectional view of an embodiment having a flow cross-section narrowing in the material supply line. [Figure 5] Fig. shows a partial longitudinal sectional view of an embodiment having a static mixer in the material supply line. [Figure 6] Fig. shows a partial longitudinal sectional view of an embodiment having three additive lines arranged axially one behind the other in the material supply line. [Figure 7] Fig. shows a partial longitudinal sectional view of an embodiment having two additive lines arranged axially one behind the other in the material supply line and a static mixer arranged between the additive lines.
Best Mode for Carrying Out the Invention
[0018] FIG. 1 shows a first embodiment of a 3D concrete print head 10 for introducing concrete, mortar, etc. in a partial longitudinal cutaway view. The 3D concrete print head 10 has a housing 12 in which a mixing chamber 14 is disposed, and the mixing chamber is defined by a housing wall 16. The expressions "above", "upward", "below", "downward", and "sideways" used with respect to the accompanying drawings should not be construed as absolute, but rather relate to the depiction of the 3D concrete print head 10 shown in the drawings. It should be understood that the 3D concrete print head 10 can take any desired and necessary orientation during operation.
[0019] In the illustrated embodiment, the mixing chamber 14 is in a cylindrical form and may thus be referred to as a mixing pipe in some cases.
[0020] The mixing chamber 14 extends axially along a longitudinal axis L from an end 18 of the mixing chamber 14 at the upper part in the figure to a lower end formed by a mixing chamber outlet opening 20. In particular, the mixing chamber 14 extends here between a material supply opening 19 disposed sideways and the mixing chamber outlet opening 20. The material supply opening 19 functions to introduce concrete, mortar, etc. into the mixing chamber 14. In all embodiments shown herein, the material is introduced into the mixing chamber 14 in a circumferential region of the housing wall 16, but it is also possible to arrange for the material to be introduced in an end region of the housing wall 16, for example, at the upper end 18 of the mixing chamber 14 (not shown). In order to form sufficient space for the material supply opening 19 at the upper end 18 of the mixing chamber 14, the upper end 18 of the mixing chamber 14 may need to be made slightly wider compared to the illustrated embodiment.
[0021] The mixing chamber 14 contains an actively driveable mixing device, which here takes the form of a mixer 22 having a mixing shaft 24 extending axially through the mixing chamber 14 and fitted with a plurality of radially outward projecting mixing blades 26. An electric motor is connected to the upper end of the mixing shaft 24 and functions to rotate the mixing shaft 24, and by extension the entire mixer 22, allowing the mixing shaft 24 to rotate around its longitudinal axis L. Instead of the electric motor 28 shown herein, the mixing shaft 24 may be driven in a different way, mechanically, pneumatically, or hydraulically. The illustrated mixer 22 should likewise be considered merely an example. Instead of the illustrated mixer 22, any other mixer or any other mixing device capable of achieving the desired mixing in the mixing chamber 14 may be used.
[0022] Below the mixing chamber 14, a discharge component 30 is positioned, with its open end forming the discharge opening 32 of the 3D concrete print head 10. In the embodiments shown herein, the discharge component 30 is in any case attached to the housing 12 and may have a flow cross section that tapers conically in the flow direction. As shown in the figures, the mixing chamber outlet opening 20 of the mixing chamber 14 is fluidly connected to the discharge component 30 and, consequently, to the discharge opening 32, so that material can be discharged from the mixing chamber 14 through the discharge opening 32 during the operation of the 3D concrete print head 10.
[0023] To enable the introduction of the mixing chamber 14 for the material to be extruded, the material supply opening 19 of the mixing chamber 14 is connected to a material supply line 34, which extends outward from the material supply opening 19 and may be in the form of, for example, a supply pipe and / or a supply hose. The main components of the material mixture extruded by the 3D concrete print head are supplied to the mixing chamber 14 through the material supply line 34. For example, the material supply line 34 may be directly connected to a concrete or mortar mixing device (not shown) which produces concrete or mortar, etc., and injects it into the mixing chamber 14 of the 3D concrete print head 10 through the material supply line 34.
[0024] In order to successfully implement the 3D concrete printing process, it is generally necessary to add one or more additional substances to the material to be processed, which is supplied to the mixing chamber 14 through the material supply line 34, in order to precisely adjust the properties of the material mixture extruded by the 3D concrete print head 10. These additional substances are referred to here as additives.
[0025] To introduce such additional substances into the material to be processed by the 3D concrete print head 10, at least one additive line 36 is used, having an end 38 located in the material supply line 34. The end 38 has an additive opening 40 into which the additive line 36 opens directly into the material supply line 34. The additive opening 40 is positioned before the material supply opening 19, when viewed in the direction of flow of the material flowing through the material supply line 34, so that the additive supplied through such an additive line 36 can mix with the material flowing through the material supply line 34 even before the additive enters the mixing chamber 14. In other words, the additive opening 40 is located upstream of the material supply opening 19, at a distance X from the housing wall 16 of the mixing chamber 14. This distance X is such that the material flowing through the material supply line 34 (which at this time includes the additive or a plurality of additives) is sufficiently and thoroughly mixed in this portion X even before it enters the mixing chamber 14. The distance X should be at least approximately equal to the diameter of the material supply opening 19, but the distance X may be a multiple of the diameter of the material supply opening 19, for example, 2, 3, 4, or 5 times the diameter. Larger distances X are also possible in principle. In the mixing chamber 14, the material mixture that enters through the material supply opening 19 is then further mixed and homogenized.
[0026] In the exemplary embodiment shown in Figure 1, the additive line 36 enters the material supply line 34 laterally, and then the end 38 of the additive line 36 is inserted axially within the material supply line 34, i.e., in the direction of the material flow into the material supply line 34. However, the additive line 36 may be inserted into the material supply line 34 in a manner other than that shown, for example, from the rear relative to the flow (not shown).
[0027] Figures 1a to 1e show cross-sectional views of AA in Figure 1, respectively, of various configurations of the arrangement of one or more additive lines 36 in the material supply line 34. Figure 1a substantially corresponds to the embodiment shown in Figure 1, where the additive line 36 comprises only a single channel 42 for supplying additives to the material supply line 34. According to this exemplary embodiment, the end 38 of the additive line 36 is positioned concentrically with the cross-section of the material supply line 34, that is, the end face 44 of the end 38, which is the end face containing the additive opening 40, and the cross-section of the material supply line 34, which is circular, share the same center. However, the end 38 of the additive line 36 does not necessarily have to be positioned in the center of the material supply line 34 in this way, and may be positioned eccentrically in the material supply line 34 (not shown). The material supply line 34 also does not have to have a circular cross-section.
[0028] Figure 1b shows an exemplary embodiment similar to Figure 1a, but in contrast to Figure 1a, the additive line 36' has a rectangular cross-section instead of a circular one. Furthermore, the additive line 36' includes two channels 46, 48, each having an additive opening 40', 40'', thereby allowing two additives to be introduced into the material supply line 34 according to this embodiment. The end 38 of the additive line 36' is oriented axially in the material supply line 34, as in Figure 1, and its center is at the center of the cross-section of the material supply line 34. As described above with respect to Figure 1a, an eccentric arrangement is also possible here (not shown).
[0029] Figure 1c shows another exemplary embodiment in which the corresponding ends 38 of each of the three additive lines 36a, 36b, and 36c project radially into the material supply line 34. The additive lines 36a, 36b, and 36c are offset from each other in the circumferential direction of the material supply line 34, and in each exemplary embodiment they are offset by 120° from each other, but they all open into the material supply line 34 at the same point when viewed in the axial direction of the material supply line 34. According to Figure 1c, it is possible to introduce three different additives into the material supply line 34 into the core of the flow into the material supply line 34, and these three additives mix with each other immediately after exiting the corresponding additive lines 36a, 36b, and 36c through the additive openings 40a, 40b, or 40c as a result of converging with each other. In modified embodiments not shown herein, the additive lines 36a, 36b, and 36c are positioned offset in the axial direction of the material supply line 34, in which case they do not open into the material supply line 34 at the same point. The offset of the additive lines 36a, 36b, and 36c in the circumferential direction of the material supply line 34 can also be provided in this modified embodiment, but may be omitted.
[0030] Figure 1d shows a configuration similar to Figure 1c, having only two additive lines 36a and 36b, in which case, according to this exemplary embodiment, these lines are arranged opposite each other. Arrangements in which the additive lines 36a and 36b are not opposite each other are also possible (not shown). Otherwise, the description made with respect to Figure 1c applies similarly, namely, the two additive lines 36a and 36b may open into the material supply line 34 at the same point in the axial direction of the material supply line 34, or at points separated in the axial direction.
[0031] Figure 1e shows a further modified embodiment in which the ends 38 of two additive lines 36a and 36b project tangentially into the material supply line 34 and are offset from each other in the circumferential direction of the material supply line 34. In such a tangential arrangement of the ends 38 of the additive lines 36a and 36b, the introduced additives do not directly collide with each other in the core of the flow flowing through the material supply line 34. Instead, such tangential arrangement of the ends 38 with respect to the cross-section of the material supply line 34 imparts a vortex action to the flow in the material supply line 34, which promotes complete mixing of the introduced additives with each other and also promotes complete mixing with the material in the material supply line 34. As already described above, the ends 38 may, again, be located at the same point on the material supply line 34 when viewed axially, or they may be axially separated from each other. Instead of the two additive lines 36a and 36b shown in Figure 1e, there may be multiple additive lines having a tangential arrangement, especially when the introduction points to the material supply line 34 are axially separated from each other, and of course, there may be only a single additive line having a tangential arrangement. In addition, the embodiments shown in Figures 1c to 1e may be combined with each other, that is, some additive lines may open into the material supply line 34 at the same axial point, while other additive lines may be axially separated from this axial point and, if necessary, from each other. Also, some ends 38 of the additive lines may have a tangential arrangement as shown in Figure 1e, and other ends may be radially arranged. Combinations with the exemplary embodiments shown in Figures 1a and 1b are also possible, that is, for example, one or two additives may be introduced into the material supply line 34 in the arrangement shown in Figure 1a or Figure 1b, while further additives are supplied in the arrangements shown in Figures 1c to 1e.
[0032] Figure 2 shows a further configuration of the additive line 36', whose arrangement generally corresponds to the arrangement shown in Figure 1. Similar to the additive line 36' shown in Figure 1b, the additive line shown in Figure 2 also has two channels 46 and 48, but in the configuration shown in Figure 2, these channels 46 and 48 are arranged concentrically with respect to each other. Channel 46 has a circular flow cross-section, while channel 48 has an annular flow cross-section.
[0033] Figure 3 shows a modified embodiment from Figure 2 in which the end 38 of the additive line 36 is mounted to be displaceable in the axial direction. Thus, as indicated by arrow P, the distance X from the housing wall 16 or material supply opening 19 to the additive opening 40 can be varied. Thus, the distance X can be adapted to the mixing characteristics of the supplied additive, at least within a certain limit, and a longer portion X can be provided for such additives to mix with the material flowing in the material supply line 34, for example. As shown in Figure 3, if the bearing devices 50, 52 are provided with flow openings 54, the space concentrically surrounding the additive line 36 can be used to supply further additives into the material supply line 34, similar to the embodiment in Figure 2.
[0034] Figure 4 shows an arrangement similar to the embodiment shown in Figure 1, wherein the material supply line 34 has a flow cross-section constriction, the flow cross-section constriction being located downstream of the additive opening 40 and upstream of the material supply opening 19. In the illustrated exemplary embodiment, the flow cross-section constriction is in the form of a Laval nozzle 56. Any flow cross-section constriction, but in particular a Laval nozzle, results in an increase in flow velocity in the region of the flow cross-section constriction, thereby promoting the mixing of the additive supplied through the additive line 36 with the material flowing into the material supply line 34. If the Laval nozzle 56 is located near the material supply opening 19 as shown, such a Laval nozzle also accelerates the inflow of the material mixture flowing into the material supply line 34 into the mixing chamber 14, which also contributes to better mixing.
[0035] Figure 5 shows a modified embodiment in which a static mixer 58 is positioned downstream of the additive opening 40 and upstream of the material supply opening 19 in the material supply line 34, instead of the Laval nozzle 56 shown in Figure 4. Such a static mixer provides homogeneous mixing of the additive being fed into the material supply line 34 with the material already flowing through the material supply line 34, over a relatively short section.
[0036] Figure 6 shows an embodiment similar to that in Figure 1, in which three additive lines 36a, 36b, and 36c are arranged such that their ends 38 are aligned axially and front to back in the material supply line 34. In other words, the ends 38 are continuous along the axial direction when viewed in the flow direction of the material supply line 34.
[0037] Finally, Figure 7 shows an embodiment similar to Figure 6, having only two additive lines 36a and 36b, in which a static mixer 58 is positioned between the two additive openings 40b and 40a of the additive lines 36b and 36a to provide homogeneous mixing of the additive introduced through additive line 36b and the material flowing into the material supply line 34, the additive openings being continuous along the flow direction of the material supply line 34. Such a static mixer, or an alternative flow cross-section constriction, can of course be used multiple times as appropriate, i.e., at the rear of one, more or all of the additive openings 40a, 40b and 40c, in the embodiment shown in Figure 6.
Claims
1. A 3D concrete print head (10) for two-component or multi-component materials, A housing (12), and a mixing chamber (14) located within the housing (12) and defined by the housing wall (16), A material supply line (34) having a material supply opening (19) that opens into the mixing chamber (14), At least one additive line (36) having an end (38) located in the material supply line (34), An actively drivable mixing device is arranged in the mixing chamber (14), A mixing chamber outlet opening (20), wherein the mixing chamber (14) extends along its longitudinal axis (L) at least between the material supply opening (19) and the mixing chamber outlet opening (20), The discharge opening (32) is connected to the outlet opening (20) of the mixing chamber and It has, The at least one additive line (36) opens into the material supply line (34) through an additive opening (40), the additive opening (40) is located upstream of the material supply opening (19) and at a distance (X) from the housing wall (16) of the mixing chamber (14). 3D concrete print head.
2. The 3D concrete print head according to claim 1, wherein the additive line (36') comprises two or more channels (46, 48) each opening into the material supply line (34) via additive openings (40', 40'').
3. The 3D concrete print head according to claim 1 or 2, wherein the end (38) of the additive line (36, 36') is arranged concentrically with the material supply line (34).
4. The 3D concrete print head according to any one of claims 1 to 3, wherein the end (38) of the additive line (36) is mounted so as to be displaceable in the axial direction, such that the distance (X) from the housing wall (16) of the mixing chamber (14) to the additive opening (40) is variable.
5. The 3D concrete print head according to any one of claims 1 to 4, wherein the flow cross-section constriction portion, in particular the form of a Laval nozzle (56), is located in the material supply line (34) downstream of the additive opening (40) and upstream of the material supply opening (19).
6. The 3D concrete print head according to any one of claims 1 to 5, wherein a static mixer (58) is located in the material supply line (34) downstream of the additive opening (40) and upstream of the material supply opening (19).
7. The 3D concrete print head according to any one of claims 1 to 3, wherein the additive openings (40a, 40b, 40c) of a plurality of additive lines (36a, 36b, 36c), each having its end portion (38) positioned on the material supply line (34), open into the material supply line (34).
8. The 3D concrete print head according to claim 7, wherein the plurality of additive lines (36a, 36b, 36c) open into the material supply line (34) at the same point when viewed in the flow direction of the material supply line (34).
9. The 3D concrete print head according to claim 8, wherein the ends (38) of the plurality of additive lines (36a, 36b, 36c) protrude radially into the material supply line (34) and are arranged offset from each other in the circumferential direction of the material supply line (34).
10. The 3D concrete print head according to claim 8, wherein the ends (38) of the plurality of additive lines (36a, 36b) protrude tangentially into the material supply line (34) and are arranged offset from each other in the circumferential direction of the material supply line (34).
11. The 3D concrete print head according to claim 7, wherein the additive openings (40a, 40b, 40c) of the plurality of additive lines (36a, 36b, 36c) are arranged in a front-to-back direction when viewed in the flow direction of the material supply line (34).
12. The 3D concrete print head according to claim 11, wherein the ends (38) of the plurality of additive lines (36a, 36b, 36c) protrude radially or tangentially into the material supply line (34), and are preferably offset from one another in the circumferential direction of the material supply line (34).
13. The 3D concrete print head according to claim 7, wherein the ends (38) of the plurality of additive lines (36a, 36b, 36c) are arranged axially and front to back in the material supply line (34).
14. A 3D concrete print head according to claim 13, wherein a flow cross-section constriction, in the form of a static mixer (58) or, in particular, a Laval nozzle (56), is positioned in the material supply line (34) between the two additive openings (40a, 40b, 40c) of the plurality of additive lines (36a, 36b, 36c), and the additive openings are continuous along the flow direction of the material supply line (34).