3D printing nozzle system for construction

Abstract

The present invention relates to a 3D printing nozzle system for construction. The 3D printing nozzle system for construction according to the present invention is characterized by being installed in the end effector of a 3D printer and comprising a mixing tank in which mortar and an admixture introduced through each passage are mixed to form a composite material, a nozzle connected to the mixing tank to discharge the composite material, a rotating shaft installed in the mixing tank and rotating, a plurality of first blades spaced apart from each other along the longitudinal direction of the rotating shaft to protrude from the rotating shaft and mix the composite material within the mixing tank, a plurality of second blades arranged between the first blades along the height direction of the mixing tank and formed to protrude from the inner wall surface of the mixing tank, and a mixing unit having an elastic lining pad installed along the inner wall surface of the mixing tank that is compressible and expandable.

Description

Technology Field

[0001] The present invention relates to a construction technology for constructing a building by 3D printing concrete, and in particular to a nozzle system for discharging concrete from a 3D printer. Background Technology

[0003] A 3D printer refers to a three-dimensional injection molding machine that forms a desired product in three dimensions by stacking layers one by one based on a three-dimensional model. When 3D printers were first introduced, printing materials were limited to plastic resins, and the technology was only used to manufacture small-sized mock-up products; however, with technological advancements, the range of printing materials has expanded significantly. Recently, 3D printing technology is also being utilized in the automotive, aerospace, and medical fields.

[0004] 3D printing is also being utilized in the construction sector.

[0005] A building is constructed by stacking layers along a 3D modeled shape using a composite material mixed with cement mixture, ceramic resin, or inorganic materials such as metal powder or carbon.

[0006] In architectural 3D printing, composite materials are used that combine various materials such as cement (mortar), admixtures like rapid setting agents and water-reducing agents, and dyes. While general construction also uses concrete composite materials to form a mold, pour concrete, and cure it, 3D printing in architecture involves layering composite materials, making the management of the material properties particularly important. For example, if the viscosity is too low, the designed shape and strength cannot be maintained after extrusion from the printer; on the other hand, if the viscosity is too high, extrusion is difficult, and if it cures too quickly, there is a problem where the integrity with subsequent layers is reduced due to the cold joint phenomenon.

[0007] In a 3D printing system for construction, the materials are not all mixed in a single mixing tank and then transferred to a nozzle; instead, the system is configured to mix the mortar and admixture within the nozzle system and discharge them immediately.

[0008] However, since 3D printing mortar uses a thick paste with a low water content, it is not easy for admixtures such as quick-setting agents to be evenly mixed and dispersed within the nozzle system. Consequently, there is a problem in that the mortar composition is not uniform overall, making it difficult to achieve the desired physical properties. However, in conventional architectural 3D printing, the mortar and admixtures are aggregated solely by the rotational force of a screw for material transport without separate external power, making it very difficult to ensure material uniformity. The problem to be solved

[0010] The present invention aims to solve the aforementioned problems and provides a construction 3D printing nozzle system with an improved structure so that materials such as mortar and admixtures are evenly mixed and stirred in the construction 3D printing system, thereby enabling the physical properties of the composite material to be stably expressed.

[0011] Meanwhile, other unspecified objectives of the present invention will be further considered to the extent that they can be easily inferred from the following detailed description and effects. means of solving the problem

[0013] A 3D printing nozzle system for construction according to the present invention for achieving the above objective comprises: a mixing tank installed in the end effector of a 3D printer, wherein mortar and an admixture introduced through each passage are mixed to form a composite material;

[0014] A nozzle connected to the above stirring tank for discharging the composite material;

[0015] The stirring unit is characterized by comprising: a rotating shaft installed in the stirring tank and rotating therein; a plurality of first blades spaced apart from each other along the longitudinal direction of the rotating shaft to protrude from the rotating shaft and stir a composite material within the stirring tank; a plurality of second blades arranged between the first blades along the height direction of the stirring tank and formed to protrude from the inner wall surface of the stirring tank; and an elastic lining pad installed along the inner wall surface of the stirring tank and capable of compression and expansion.

[0016] According to the present invention, a carbon dioxide input pipe is further provided to supply carbon dioxide gas to the stirring tank, and the carbon dioxide combines with calcium within the stirring tank to form calcium carbonate.

[0017] In one example of the present invention, a heating unit that wraps around the carbon dioxide input tube to raise the temperature may be further provided.

[0018] In one example of the present invention, the lining pad is preferably made of a flexible rubber material.

[0019] In one example of the present invention, a fluid may be filled between the inner wall of the stirring tank and the lining pad to allow for expansion and contraction of the lining pad. In particular, air may be filled between the inner wall of the stirring tank and the lining pad, and it is preferable that the filling pressure of the air be adjustable.

[0020] In one example of the present invention, the inner wall of the stirring tank has grooves formed concavely along the vertical direction arranged at regular intervals, so that a space is formed between the lining pad and the grooves, and when the lining pad is pressurized, it expands toward the grooves and returns to its original state when the pressure is released. Effects of the invention

[0022] The present invention provides a nozzle system for forming a composite material by evenly mixing various materials, such as mortar, admixtures, and dyes, in 3D printing for construction. In the nozzle system according to the present invention, not only can the materials be evenly mixed by the first blade and the second blade, but the mixing efficiency of the composite material is further enhanced by applying additional vibration to the composite material using a lining pad formed on the inner wall of the mixing tank. Through this, the physical properties of the composite material required for 3D printing for construction can meet established standards. Since buildings are formed by layering composite materials in 3D printing for construction, managing the physical properties of the composite material is much more important than in general construction or 3D printing of general plastic products, and it is expected that these requirements for physical properties can be met by utilizing the nozzle system according to the present invention.

[0023] Meanwhile, it should be added that even if an effect is not explicitly mentioned here, the effects described in the following specification and the provisional effects expected by the technical features of the present invention are treated as described in the specification of the present invention. Brief explanation of the drawing

[0025] FIG. 1 is a schematic cross-sectional view of a nozzle system according to a first embodiment of the present invention. Figure 2 is a schematic cross-sectional view along line AA of Figure 1. FIG. 3 is a schematic perspective view for explaining the shape of the first blade of the rotation axis. Figure 4 is a diagram illustrating the elastic action of the liner pad. FIG. 5 is a schematic cross-sectional view of a nozzle system according to a second embodiment of the present invention. ※ It should be noted that the attached drawings are provided as examples for reference to help understand the technical concept of the present invention, and the scope of the rights of the present invention is not limited by them. Specific details for implementing the invention

[0026] In describing the present invention, detailed descriptions of related known functions are omitted if they are deemed obvious to a person skilled in the art and could unnecessarily obscure the essence of the invention.

[0027] With reference to the attached drawings, the 3D printing nozzle system for construction according to the present invention will be described in more detail below.

[0028] FIG. 1 is a schematic cross-sectional view of a nozzle system according to a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view along line AA of FIG. 1, and FIG. 3 is a schematic perspective view for explaining the shape of a first blade of a rotating shaft.

[0029] Referring to the drawings, the nozzle system (100) according to the first embodiment is intended to finally eject a mortar composite material as a component of a 3D printing system for construction. While 3D printing systems for construction have been developed in various forms, this nozzle system is applicable to all 3D printing systems. This example is installed on the end effector of a robot-type 3D printer that can move freely using an endless track. When the end effector is positioned at the composite material ejection location, the composite material is ejected through the nozzle system.

[0030] The nozzle system according to the first embodiment comprises a stirring tank (10), a nozzle (30), and a stirring unit (90).

[0031] The mixing tank (10) receives mortar, admixture, dye, etc., mixes and mixes them, and discharges the mixed composite material. In this example, the mixing tank (10) is formed in a cylindrical shape overall, and the lower part is formed so that the diameter gradually narrows.

[0032] The upper part of the mixing tank (10) is open to allow mortar to be introduced, and the lower part has an outlet (11) for discharging the composite material after mixing is complete. Additionally, a supply pipe (12) for introducing admixtures such as a rapid-setting agent and a water-reducing agent, and an injection pipe (13) for introducing dye are respectively connected to the mixing tank (10). A control unit (not shown) for controlling the amount of admixture is provided in the admixture injection pipe.

[0033] In addition, a carbon dioxide injection pipe (14) for injecting carbon dioxide gas is connected to the upper side of the stirring tank (10). The carbon dioxide injection pipe (14) will be explained again later.

[0034] The nozzle (30) is connected to the lower discharge port (11) of the mixing tank (10). The composite material is finally discharged through the nozzle (30). Although not shown, the nozzle is provided with a pinch valve and a pressure reducing valve to solve the problem of unstable discharge of the composite material due to pressure imbalance when the nozzle is opened and closed instantaneously. In addition, a calibrator (not shown) is installed in the nozzle to precisely control the discharge position of the nozzle.

[0035] The stirring unit (90) ensures that various materials such as mortar, admixtures, and dyes are evenly stirred so that specific materials are not concentrated in specific parts but are evenly dispersed throughout. Additionally, the composite materials are stirred to maintain constant fluidity and then transferred to the nozzle (30). The reason why stirring of composite materials is important in a 3D printing system is as explained in the prior art.

[0036] To this end, the stirring unit (90) is equipped with a rotating shaft (60). The rotating shaft (60) is formed vertically along the arrangement direction of the stirring tank (10) and is installed rotatably at the center of the stirring tank. The upper part of the rotating shaft (60) is connected to a driving unit (65) equipped with a servo motor and a reduction gear to receive rotational force. Although a separate driving source for stirring materials was not used in the past, the present invention enables stirring of materials at high speed using a servo motor. In addition, a torque sensor (66) is installed on the upper part of the rotating shaft (60) to measure the viscosity of the composite material. Since the driving unit and the torque sensor are known components, a detailed description is omitted.

[0037] A plurality of first blades (61) are provided on the rotation axis (60). The first blades (61) are arranged to protrude radially from the rotation axis (60) to agitate the composite material in the mixing tank. In this example, the first blades (61) are arranged at 90° intervals along the circumferential direction as shown in FIG. 2 and are arranged continuously at regular intervals along the vertical direction. As shown in FIG. 3, the first blades (61) are arranged at an angle (θ) downward and are formed to rotate and push the composite material downward as shown by the arrow (C).

[0038] Additionally, a plurality of second blades (62) are fixedly installed on the inner wall surface of the stirring tank (10). The second blades (62) are formed to protrude from the inner wall surface and are arranged between the first blades (61) along the vertical direction. The second blades (62) are also arranged at 90° intervals along the circumferential direction. As shown in FIG. 1, the first blades (61) and the second blades (62) are arranged alternately along the vertical direction so as not to overlap each other, thereby stirring the composite materials inside the stirring tank (10).

[0039] In the present invention, a lining pad (70) is provided in addition to the first blade (61) and second blade (62) described above to promote stirring of the composite material. The lining pad (70) is made of an elastic rubber material capable of shrinking and expanding, such as EPDM, and is installed along the inner wall surface of the stirring tank (10). In addition, in the first embodiment, the lining pad (70) is positioned at a certain distance from the inner wall surface of the stirring tank (10), and a space (71) is formed between the inner wall of the stirring tank (10) and the lining pad (70). This space (71) is sealed and filled with a fluid with fluidity, such as air, gas, water, or gel material. When the first blade (61) rotates in the mixing tank (10), the composite materials are pushed in the direction of the inner wall along the rotation path as indicated by the arrow (K) of the mixing tank, thereby pressing the lining pad (70). The elastic lining pad (70) expands as it is pushed toward the space (71) by the pressure of the composite materials, as shown by the dotted line in FIG. 4. After the first blade passes, the pressure is released, and the lining pad (70) returns to its original position due to its elasticity. The lining pad (70) repeatedly contracts and expands along the radial direction in coordination with the first blade, thereby imparting vibration to the composite materials and further increasing the mixing efficiency of the composite materials.

[0040] In this example, the space (71) can be filled with air, and furthermore, the pressure of the filled air can be adjusted. That is, the filling pressure is adjusted by pressurizing and filling the sealed space. If the viscosity of the composite material is low, the filling pressure is adjusted to a low level, and if the viscosity is high, the filling pressure is adjusted to a high level, thereby enabling effective stirring.

[0041] Meanwhile, in the nozzle system according to the present invention, carbon dioxide is injected into the composite material to induce carbon mineralization. When carbon dioxide is injected into the mixing tank, it dissolves in water and is converted into carbonate ions, which combine with divalent cations such as calcium leached from cement to precipitate calcium carbonate. The calcium carbonate formed through this carbon mineralization has a small particle size, which increases the density within the hardened composite material and contributes to the development of strength in the composite material. Additionally, by immobilizing carbon dioxide in the composite material, it can contribute to the treatment of carbon dioxide, a greenhouse gas. In this example, carbon dioxide is introduced into the mixing tank at atmospheric pressure while in a compressed state, causing it to expand and lower its temperature. This temperature drop can affect the physical properties of the composite material and may cause condensation. Therefore, in this example, a heating unit (20) containing a heating wire is wrapped around the carbon dioxide injection pipe (16) to prevent condensation. Meanwhile, the carbon dioxide injection pipe can be utilized as a water washing pipe to clean the mixing tank. That is, water can be injected into the carbon dioxide injection pipe to remove materials remaining in the mixing tank.

[0042] Meanwhile, FIG. 5 is a schematic cross-sectional view of a nozzle system according to a second embodiment of the present invention.

[0043] The second embodiment is identical to the first embodiment in all its configurations, but differs in that the inner wall of the mixing tank is formed in an uneven shape. Referring to FIG. 5, in the nozzle system (200) according to the second embodiment, an annular groove (81) is formed concavely on the inner wall surface. In addition, this groove (81) is continuously arranged at regular intervals along the vertical direction of the inner wall surface, and the height at which the multiple grooves (81) are arranged corresponds to the height at which the first blades (61) are arranged. The lining pad (70) is in close contact with the flat portion of the inner wall surface. Therefore, in the portion of the inner wall surface of the mixing tank where the groove (81) is formed, the lining pad (70) cannot be attached to the inner wall surface, and a space (82) is formed between it and the inner wall surface. Similar to the first embodiment, fluid is filled into this space to provide a space that allows for the expansion and contraction of the lining pad. Therefore, as the composite material is pressurized by the rotation of the first blade and pushes the lining pad, the lining pad (70) expands toward the groove, and after the first blade passes and the pressure is released, it is elastically restored. During this process, vibration is applied to the composite material, increasing the stirring efficiency.

[0044] As described above, the present invention provides a nozzle system for forming a composite material by evenly mixing various materials, such as mortar, admixtures, and dyes, in 3D printing for construction. In the nozzle system according to the present invention, not only can the materials be evenly mixed by the first blade and the second blade, but the mixing efficiency of the composite material is further enhanced by applying additional vibration to the composite material using a lining pad formed on the inner wall of the mixing tank. Through this, the physical properties of the composite material required for 3D printing for construction can meet the established standards. Since buildings are formed by layering composite materials in 3D printing for construction, the management of the physical properties of the composite material is much more important than in general construction or 3D printing of general plastic products, and it is expected that these requirements for physical properties can be met by utilizing the nozzle system according to the present invention.

[0045] Meanwhile, although the first and second embodiments have described and illustrated a configuration in which a space is formed between the lining pad and the inner wall of the mixing tank and filled with fluid, in other embodiments of the present invention, this effect can be achieved through the elasticity of the rubber lining pad itself without forming a space. As previously explained, since the 3D printing composite material for construction uses a thick paste with very high viscosity, the rubber pad can be compressed by applying pressure even when it is in close contact with the mixing tank. Although the degree of elasticity is lower compared to the case where a space is formed, a certain level of vibration can be applied to the composite material.

[0046] The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. Furthermore, it is added once again that the scope of protection of the present invention cannot be limited by obvious changes or substitutions in the technical field to which the present invention belongs. Explanation of the symbols

[0049] 100, 200 ... Architectural 3D printer nozzle system 10 ... stirring tank, 11 ... discharge port 12 ... supply pipe, 13 ... injection pipe 14 ... carbon dioxide inlet pipe, 20 ... heating unit 30 ... nozzle, 61 ... first blade 62 ... 2nd Blade, 65 ... Drive Unit 66 ... torque sensor, 70 ... lining pad 71, 82 ... space section, 81 ... groove section 90 ... stirring unit

Claims

Claim 1 A 3D printing nozzle system for construction, comprising: a stirring tank installed in the end effector of a 3D printer, wherein mortar and an admixture introduced through each passage are mixed to form a composite material; a nozzle connected to the stirring tank to discharge the composite material; a stirring unit comprising a rotating shaft installed in the stirring tank and rotating, a plurality of first blades spaced apart from each other along the longitudinal direction of the rotating shaft to protrude from the rotating shaft and stir the composite material within the stirring tank, a plurality of second blades arranged between the first blades along the height direction of the stirring tank and formed to protrude from the inner wall surface of the stirring tank, and an elastic lining pad installed along the inner wall surface of the stirring tank that is compressible and expandable; wherein a fluid is filled between the inner wall of the stirring tank and the lining pad to allow the expansion and contraction of the lining pad. Claim 2 A 3D printing nozzle system for construction according to claim 1, further comprising a carbon dioxide input pipe through which carbon dioxide gas is supplied to the stirring tank, wherein the carbon dioxide combines with calcium within the stirring tank to form calcium carbonate. Claim 3 A 3D printing nozzle system for construction according to claim 2, further comprising a heating unit that surrounds the carbon dioxide injection pipe to raise the temperature. Claim 4 A 3D printing nozzle system for construction according to claim 1, characterized in that the lining pad is made of a flexible rubber material. Claim 5 delete Claim 6 A 3D printing nozzle system for construction according to claim 1, characterized in that air is filled between the inner wall of the mixing tank and the lining pad, and the filling pressure of the air is adjustable. Claim 7 A 3D printing nozzle system for construction according to claim 1, wherein the inner wall of the stirring tank has grooves formed concavely along the vertical direction arranged at regular intervals, a space is formed between the lining pad and the grooves, and the lining pad expands toward the grooves when pressurized and returns to its original state when the pressurization is released.

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