3D printing head

Abstract

This invention relates to a printhead (1) for pumpable plastic-viscosity mixtures, such as for 3D concrete printing or 3D mortar printing. The printhead (1) includes: a mixing chamber (2) having a sidewall (21), a supply opening (3), and an outlet (4) designed as a nozzle element (41); means for connecting a material delivery hose (31) at the supply opening (3) of the mixing chamber (2); and at least one jetting device (5) having a jetting nozzle (51) for jetting at least one liquid additive. According to the invention, two or more jetting nozzles (51) are arranged on the printhead (1) at the sidewall (21) of the mixing chamber (2). Furthermore, the plurality of jetting nozzles (51) are connected via a single supply line (52) for jetting.

Description

[0001] The present invention relates to a 3D printing head according to the preamble of claim 1.

[0002] In the processing of shotcrete, nozzle systems designed as 3D printing heads for ejecting concrete, mortar, etc., are known. When rapid hardening of the material to be processed is desired, an additive can be added to the concrete, mortar, etc., shortly before ejection, ideally having already been thoroughly mixed in the nozzle.

[0003] For example, a nozzle implemented as a 3D printing head for discharging concrete or mortar is known from DE 10 2020 003 760 A1, having a housing and an elastic material mixing chamber defined by a peripheral wall disposed within the housing. The mixing chamber extends along a longitudinal axis at least between a supply opening and an outlet. An actively driven mixing device in the form of a stirrer is arranged within the mixing chamber. A tapered discharge opening is fluid-guidedly connected to the outlet of the mixing chamber, at which concrete or mortar is discharged from the nozzle. A cavity extending axially and circumferentially between the elastic peripheral wall of the mixing chamber and the surrounding housing is arranged, substantially surrounding the mixing chamber circumferentially. During nozzle operation, the elastic peripheral wall of the mixing chamber can deform into the cavity. This prevents the formation of deposits on the peripheral wall of the mixing chamber.

[0004] Similarly, a nozzle for discharging concrete or mortar is known, for example, from EP 3 431 172 A1. The nozzle has a main opening for supplying concrete, at least one additional opening for supplying additives, particularly setting accelerators, and a discharge opening. An actively driven mixing mechanism with a mixing tube is provided between the additional opening and the discharge opening. To enable the use of this nozzle for 3D printing, the inner diameter of the mixing tube is specified to be at most 8 cm, preferably at most 6 cm, and particularly 2-4 cm. The process can be designed so that the concrete or mortar has already begun to harden in the nozzle. Due to the narrow mixing tube, the concrete can be discharged from the nozzle uniformly, precisely, and point-to-point. A valve for briefly stopping the material flow can be provided between the mixing mechanism and the discharge opening. Furthermore, the nozzle can have a compressed air inlet for blowing out the concrete, so that material discharge can also be carried out using compressed air.

[0005] The principles of manufacturing and processing colored concrete are already known in the field of concrete construction. During the mixing process, liquid or solid coloring materials are added to the components of the concrete formula. This colors the entire material, which is then processed.

[0006] Against this backdrop, an apparatus for manufacturing buildings or objects from colored concrete is known from DE 10 2021 121 046 A1. This apparatus operates quickly, efficiently, and reliably, and is easy to clean. The described apparatus is for 3D concrete printing, comprising an extruder implemented as a 3D printing head, movably fixed to a robotic arm. The extruder has an inlet and a nozzle outlet, and a delivery channel for a flow of liquid concrete located between them. A concrete delivery pump and a concrete delivery hose for supplying liquid concrete are connected upstream of the extruder. The extruder also has a spraying device for injecting a setting accelerator into a mixing pipe or mixing chamber to mix with the liquid concrete flow. Furthermore, another spraying device is provided for injecting at least one colorant into the liquid concrete flow, wherein, viewed from the flow direction of the liquid concrete flow, the spraying device for the corresponding colorant is arranged before the spraying device for the setting accelerator.

[0007] For nozzle systems implemented as 3D printing heads, the following problem exists in principle: due to the additives mixed in that promote the hardening of concrete or mortar, more deposits may form inside the nozzle. It is particularly important to be able to add these additives in a targeted and extremely precise dosage when flow through the nozzle temporarily stops and then resumes.

[0008] The purpose of this invention is to further improve the efficiency and reliability of 3D printing heads.

[0009] This objective is achieved by a 3D printing head having the features of independent claim 1. The dependent claims relate to advantageous improvements and variations of the invention.

[0010] This invention includes a printhead for pumpable plastic-viscosity mixtures, such as for 3D concrete printing or 3D mortar printing. The printhead includes:

[0011] A mixing chamber having side walls, a supply opening, and an outlet designed as a nozzle element;

[0012] A device for connecting a material delivery hose at the supply opening of the mixing chamber;

[0013] At least one spraying device having a spray nozzle for spraying at least one liquid additive.

[0014] According to the present invention, two or more jet nozzles are arranged on the side wall of the mixing chamber on the print head. Furthermore, the multiple jet nozzles are connected via a single supply line for jetting.

[0015] Preferably, all injection nozzles may be connected to a single supply line for injection. In this case, the supply line may surround the sidewall of the mixing chamber to supply the injection nozzles.

[0016] In this way, liquid additives, such as setting accelerators or color mixtures, are supplied from a central supply unit to the spray nozzles. The central supply unit also allows for uniform control of the pressure state of all spray nozzles and corresponding adjustment of delivery capacity. Precise control of spray initiation, spray volume, and the spraying process is possible using electronic controls and pneumatic cylinders. Preferably, during spraying, the valves do not open and close simultaneously, but rather sequentially along the circumferential sidewall of the mixing chamber. Typically, at least one valve is always open during operation. It is also envisioned that the mixing ratio of the liquid additive with the viscous mortar or concrete can be adjusted by simultaneously opening a certain number of valves.

[0017] A particular advantage of this invention lies in this special spraying method, which ensures uniform pressure at each nozzle, thereby making the plastic-viscosity mixture particularly uniform with the liquid additive.

[0018] In a preferred embodiment of the invention, the supply line at the sidewall of the mixing chamber can be designed as an annular channel supplying the injection nozzle. The annular channel may partially or completely surround the mixing chamber at the sidewall. The injection nozzle then enters the annular channel to inject the at least one liquid additive into the mixing chamber. The specific design of the annular channel and the positioning of the injection nozzle, the geometry of the mixing chamber, and the associated material flow of the plastic-viscosity mixture may be important.

[0019] Advantageously, the sidewalls of the mixing chamber can be designed to be cylindrical and / or conical, and the annular channel of the supply line can be arranged around the periphery of the mixing chamber. In this case, due to the shape of the mixing chamber, it is substantially rotationally symmetrical about a longitudinal axis, thereby allowing the material flow of the plastic-viscosity mixture to flow axially along the longitudinal axis in the injection nozzle region. To take advantage of this symmetry, the annular channel can be arranged along the entire periphery or only in segments to supply the injection nozzle.

[0020] In another preferred embodiment of the invention, the supply line at the mixing chamber can be designed as an annular shape to supply the jet nozzle. Here, the annular surface for supplying the jet nozzle surrounds the mixing chamber in a ring shape along its periphery. Therefore, the annular surface forms the annular end of the central supply line, into which the jet nozzle is connected.

[0021] In a preferred embodiment of the invention, a plurality of colorant spray nozzles for spraying colorant can be connected at the sidewall of the mixing chamber via a single colorant supply line for colorant spraying. In this design, the spraying device having spray nozzles for spraying a coagulation accelerator as a first liquid additive also includes colorant spray nozzles according to the same principle, which are also connected to and supplied to each other via another central supply line for the color mixture.

[0022] Alternatively, advantageously, the spraying device with the spray nozzle may additionally include means for spraying the colorant. In this design, the coagulation accelerator and the liquid color component are combined and introduced into the mixing chamber via the spray nozzle in a further process.

[0023] Advantageously, the device for spraying the colorant can be connected to a supply line at the mixing chamber. If the liquid additive is combined early in the central supply line, the additive can be fully to completely mixed before the mixture enters the mixing chamber via the spray nozzle. Thus, the additive is prepared for further mixing with plastic-viscosity mixtures, such as concrete or mortar, to achieve further homogeneous mixing.

[0024] In another preferred embodiment of the invention, three or more injection nozzles may be arranged at the same or different intervals between them on the sidewall of the mixing chamber. For example, the injection nozzles may be arranged in groups or pairs. Where appropriate, accessories positioned around the mixing chamber may result in the injection nozzles being arranged at different intervals between them for space reasons. The arrangement of the injection nozzles focuses on factors that substantially affect the injection characteristics and ensure uniform mixing of the liquid additive with the plastic-viscosity mixture in the mixing chamber.

[0025] In a preferred embodiment of the invention, four, six, or eight injection nozzles may be arranged on the side wall of the mixing chamber. Considering symmetry, for example for a cylindrical mixing chamber, an even number of injection nozzles may be a simple and preferred solution for achieving uniform mixing.

[0026] Advantageously, the injection nozzles can be opened individually or in groups for injection. Individual or group control of the injection nozzles allows for variable introduction of the liquid additive in terms of quantity, location, and timing. Precise quantity control of the additive is important depending on the material flow and the properties of the plastic-viscosity mixture located in the mixing chamber.

[0027] Advantageously, the adjacent, sequentially arranged injection nozzles can be opened in sequence for injection. This timing sequence can be achieved by cyclically adding the mixture to the pumpable plastic-viscosity mixture around the mixing chamber, and is associated with a stirring device within the mixing chamber.

[0028] In a preferred embodiment of the invention, the injection nozzle can be implemented as a pneumatic solenoid valve. For example, the valve is actuated by a double-acting pneumatic cylinder, which is in turn controlled by a solenoid valve. The solenoid valve alternately opens and closes the compressed air passage simultaneously. This pushes the pneumatic cylinder forward or backward. Alternatively, the injection nozzle can also be implemented as an electric cylinder.

[0029] Preferably, the spray nozzle may have a nozzle needle by means of which the spray openings arranged in the sidewall can be opened and closed. In practice, there is a risk that foreign matter, such as mortar or concrete additives, may enter the spray nozzle and prevent the liquid additive from passing through. In addition to controlling the spraying process, the nozzle needle is also adapted to mechanically unclog and clean the spray openings. For this purpose, the nozzle needle can also extend through the spray openings into the mixing chamber and, where appropriate, loosen hardened residues at the spray openings.

[0030] Advantageously, a mixing device that rotates about a central axis can be arranged inside the mixing chamber, the rotation of which is associated with the injection of the jet nozzle. A mechanical agitator is also adapted to scrape off material located on the inner wall of the mixing chamber and continue its conveying.

[0031] In another preferred embodiment of the invention, during injection, the mixing element of the mixing device can pass through a correspondingly opened injection nozzle. Thus, the injection behavior of the mixing device, for example implemented as a stirrer, and the respective valves can be coordinated. For this purpose, an element of the stirrer can be passed through a valve opening shortly after the injection of the coagulation accelerator.

[0032] Advantageously, devices for cleaning the jetting device and / or the mixing chamber can be arranged. For this purpose, flushing and drain lines are envisioned, which will remove the mixture in the material flow from the mixing chamber and the jetting device. In particular, the hardening material components should be removed from the printhead.

[0033] In another preferred design, a device for cleaning the mixing chamber can be arranged between the side wall and the agitator. For this purpose, a spray nozzle extending into the mixing chamber is preferably arranged in the upper region. Water or other cleaning fluid is applied to the spray nozzle. For example, the nozzle can automatically open as the water pressure increases, and its function does not require a separate control unit. When the water pressure decreases, the nozzle automatically closes again when a predetermined minimum pressure is reached. Electronically controlled spray nozzles can also be used for precise metering and, where appropriate, for selecting different cleaning fluids.

[0034] Advantageously, the means for cleaning the mixing chamber can be arranged at the supply opening located downstream of the material delivery hose. Since the plastic-viscosity mixture discharged from the material delivery hose comes into contact with the liquid additive in the area of ​​the supply opening, it may be advantageous to arrange an additional cleaning device in this area.

[0035] In a preferred embodiment of the invention, a modularly constructed stirrer can be arranged in the mixing chamber, wherein at least mixing blades, spacer rings, and sidewall scrapers, as modules, are arranged on the stirring shaft. For the modularly constructed stirrer, the individual modules can be variably selected according to the material flow, and can ensure particularly uniform mixing of the plastic-viscosity mixture with the liquid additive. The individual modules are fitted onto the stirring shaft and held together by end fasteners. Both the stirring shaft and the individual modules are designed to prevent relative rotation between them.

[0036] The embodiments and variations of the present invention will be described in more detail below with reference to the accompanying drawings, wherein:

[0037] Figure 1 An angled view of the printhead is shown schematically.

[0038] Figure 2 An internal view of a jet nozzle with a nozzle needle is schematically shown;

[0039] Figure 3 A schematic longitudinal cross-sectional view of the printhead is shown.

[0040] Figure 1 A schematic perspective view of a printhead 1 for discharging pumpable plastic-viscosity mixtures, such as concrete, mortar, etc., is shown. The printhead 1 has a mixing chamber 2, defined by a sidewall 21. Inside the mixing chamber 2 are arranged... Figure 1 An invisible agitator is present, which is driven to rotate by a drive unit 7. In the illustrated embodiment, the mixing chamber 2 is designed to be cylindrical.

[0041] A material delivery hose 31 for the plastic-viscosity mixture is connected to the mixing chamber 2 via the supply opening 3. An outlet 4 in the form of a nozzle element 41 is formed on the mixing chamber 2 along the material flow direction. After passing through the mixing chamber 2, the hardenable plastic material is discharged from the printhead 1 via the nozzle element 41 for processing.

[0042] An injection device 5 is arranged on the cylindrical sidewall 21 of the mixing chamber 2, the injection device having four injection nozzles 51 for injecting liquid additives into the mixing chamber 2. In the illustrated case, an annular channel 53 is formed around the entire circumference of the cylinder, and the injection nozzles 51 are connected to the annular channel. In this case, the annular channel 53 centrally supplies all four injection nozzles 51 and serves as a continuation of the supply line 52, connecting to the injection nozzles 51 for supplying liquid additives. The injection device 5 also includes another supply line as a device 55 for injecting colorant, which leads into the supply line 52. The liquid additive is in particular a coagulation accelerator or color component. Each injection nozzle 51 has a uniform pressure state during injection via the central supply line 52. As a means of cleaning the injection device 5 and the mixing chamber 2, a flushing line 6 is arranged to remove the mixture in the material flow from the mixing chamber 2 and the injection device 5 from the printhead 1 at the end of the printing process.

[0043] Figure 2 An internal view of a jet nozzle 51 with a nozzle needle 54 is schematically shown. The nozzle needle 54 is designed to enter and completely seal the jet opening 22 formed in the sidewall 21. Figure 2 In the mixed chamber 2, the nozzle needle 54 is in the open position, allowing liquid additives to enter the mixing chamber 2 from the annular channel 53 via the injection opening 22. To close the chamber, the nozzle needle 54 is moved into the injection opening 22, thereby interrupting the liquid flow. If foreign matter from the mixing chamber 2 enters the injection opening 22, it is removed when the nozzle needle 54 is closed.

[0044] Figure 3 A schematic longitudinal cross-sectional view of the printhead 1 in the region of the mixing chamber 2 is shown. An agitator 8 is arranged inside the cylindrical mixing chamber 2, and the agitator is driven to rotate by a drive unit 7.

[0045] The cleaning device 61 of the mixing chamber 2 is arranged in the upper region, between the side wall 21 and the agitator 8. Preferably, a water jet nozzle is used as the cleaning device 61. The jet nozzle 61 automatically opens when the water pressure increases. When the water pressure decreases, the jet nozzle 61 automatically closes again.

[0046] Another cleaning device 62 for cleaning the mixing chamber 2 is arranged at the supply opening 3. This portion of the printhead 1 forms a certain dead zone during the cleaning process, which is reliably removed by the other cleaning device 62.

[0047] A modularly constructed agitator 8 is arranged in the mixing chamber 2 of the printhead 1. The agitator 8 includes a stirring shaft 81 on which mixing blades 82, spacer rings 84, and sidewall scrapers 83 are arranged. These components ensure that the plastic-viscosity mixture is mixed with the liquid additive in a particularly uniform manner. The individual modules are fitted onto the stirring shaft and held together by locking nuts 85 at the ends.

[0048] At outlet 4, the hardenable plastic material, after passing through the mixing chamber 2, is discharged from the print head 1 via the nozzle element 41 for further processing.

[0049] List of reference numerals

[0050] 1. Print head

[0051] 2. Mixing Chamber

[0052] 21 Sidewall

[0053] 22 Injection opening

[0054] 3. Supply opening

[0055] 31 Material delivery hose

[0056] 4. Exports

[0057] 41 Nozzle element

[0058] 5. Spraying device

[0059] 51 Injection Nozzle

[0060] 52 Supply pipelines

[0061] 53 Circular Channel

[0062] 54 Nozzle needle

[0063] 55. Apparatus for supplying colorant

[0064] 6. Flushing pipeline

[0065] 61. Mixing chamber cleaning device, spray nozzle

[0066] 62 Supply opening cleaning device, spray nozzle

[0067] 7 drive units

[0068] 8. Mixer

[0069] 81 Stirring Shaft

[0070] 82 Mixed blades

[0071] 83 Side wall scraper

[0072] 84 Spacer Ring

[0073] 85 Locking nut

Claims

1. A printhead (1) for pumpable plastic-viscosity mixtures, for example for 3D concrete printing or 3D mortar printing, - It has a mixing chamber (2) having a side wall (21), a supply opening (3) and an outlet (4) designed as a nozzle element (41). - It has a device for connecting a material delivery hose (31) at the supply opening (3) of the mixing chamber (2), - It has at least one spraying device (5), which has a spray nozzle (51) for spraying at least one liquid additive. Its features are, - Two or more spray nozzles (51) are arranged on the side wall (21), - Multiple spray nozzles (51) are connected via a single supply line (52) for spraying.

2. The printhead (1) according to claim 1, characterized in that, At the side wall (21) of the mixing chamber (2), the supply line (52) is designed as an annular channel (53) for supplying the jet nozzle (51).

3. The printhead (1) according to claim 2, characterized in that, The sidewall (21) of the mixing chamber (2) is designed to be cylindrical and / or conical, and the annular channel (53) of the supply line (52) is arranged on the cylindrical periphery of the mixing chamber (2).

4. The printhead (1) according to claim 3, characterized in that, The supply line (52) is designed in an annular shape at the mixing chamber to supply the jet nozzle (51).

5. The printhead (1) according to any one of claims 1 to 4, characterized in that, Multiple colorant spray nozzles for spraying colorant are connected at the side wall of the mixing chamber (2) via a single colorant supply line for spraying colorant.

6. The printhead (1) according to any one of claims 1 to 4, characterized in that, The spraying device (5) having a spray nozzle (51) further includes a device (55) for spraying colorant.

7. The printhead (1) according to claim 6, characterized in that, The device (55) for spraying colorant is connected to the supply line (52) at the mixing chamber (2).

8. The printhead (1) according to any one of claims 1 to 7, characterized in that, Three or more spray nozzles (51) are arranged at the same or different intervals on the side wall (21) of the mixing chamber (2).

9. The printhead (1) according to any one of claims 1 to 8, characterized in that, Four, six or eight spray nozzles (51) are arranged on the side wall (21) of the mixing chamber (2).

10. The printhead (1) according to any one of claims 1 to 9, characterized in that, The spray nozzles (51) can be opened individually or in groups for spraying.

11. The printhead (1) according to claims 1 to 10, characterized in that, The spray nozzles (51) arranged in adjacent locations can be opened sequentially to spray.

12. The printhead (1) according to any one of claims 1 to 11, characterized in that, The injection nozzle (51) is designed as a pneumatic solenoid valve.

13. The printhead (1) according to any one of claims 1 to 12, characterized in that, The spray nozzle (51) has a nozzle needle (54) by means of which the spray opening (22) arranged in the side wall (21) can be opened and closed.

14. The printhead (1) according to any one of claims 1 to 13, characterized in that, A mixing device is arranged inside the mixing chamber (2) and rotates about a central axis. The rotation of the mixing device is related to the spraying of the spray nozzle (51).

15. The printhead (1) according to claim 14, characterized in that, During injection, the mixing element of the mixing device passes through the correspondingly opened injection nozzle (51).

16. The printhead (1) according to any one of claims 1 to 15, characterized in that, A cleaning device (6) is provided for cleaning the spraying device (5) and / or the mixing chamber (2).

17. The printhead (1) according to claim 16, characterized in that, The cleaning devices (6, 61) for cleaning the mixing chamber (2) are arranged between the side wall (21) and the agitator (8).

18. The printhead (1) according to claim 16 or 17, characterized in that, A cleaning device (6) for cleaning the mixing chamber (2) is arranged at the supply opening (3) located downstream of the material delivery hose (31).

19. The printhead (1) according to any one of claims 1 to 18, characterized in that, A modularly constructed stirrer (8) is arranged in the mixing chamber (2), wherein at least a mixing blade (82), a spacer ring (82), and a side wall scraper (84) as modules are arranged on the stirring shaft (81).

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