Method for manufacturing cement-based molded article

Abstract

To provide a method by which a cement-based molded article can be manufactured without collapse during molding by using a 3D printer.SOLUTION: A method for manufacturing a cement-based molded article is a method for additive manufacturing the cemented-based molded article by moving a nozzle that discharges a cement-based material. The cement-based molded article 23 is additively manufactured on an inclined base 31.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for producing a cement-based object using a three-dimensional (3D) printer. [Background technology]

[0002] 3D printers are being used to create objects made from cementitious materials such as concrete. These 3D printers move a nozzle that dispenses cementitious material, depositing the material layer by layer to create a shape. This method can be used to create architectural structures, street fixtures such as benches, decorations for buildings, monuments, and works of art.

[0003] For example, Patent Document 1 describes a robotic cementitious material strand extrusion system used in additive manufacturing of architectural structures, which includes a print head with an outlet nozzle designed to form strands of cementitious material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-523228 Summary of the Invention [Problem to be solved by the invention]

[0005] The cementitious material ejected from the nozzle does not harden instantly, but rather takes a certain amount of time to harden. As a result, the next layer is layered on top of a soft layer, and if the object has side walls that are significantly tilted from the vertical, gravity can cause the object to collapse during additive manufacturing. However, waiting for the ejected material to fully harden before layering the next layer would deteriorate the adhesion between layers and significantly increase the time required for modeling, making it unrealistic. Furthermore, using a mold that matches the shape of the object requires preparing a mold that matches the shape of the object each time, significantly compromising the 3D printer's unique ability to print freely curved shapes without using a mold. Furthermore, the mold can interfere with the moving nozzle, resulting in poor modeling results.

[0006] The present invention has been made in consideration of the above, and aims to provide a method for additive manufacturing of cement-based materials that can produce a molded object without it collapsing during manufacturing, even if the shape is prone to collapse during manufacturing. [Means for solving the problem]

[0007] The method for manufacturing a cement-based object of the present invention is a method for additive manufacturing of a cement-based object by moving a nozzle that dispenses a cement-based material, characterized in that the cement-based object is additively manufactured on an inclined base. The cement-based material includes mortar, concrete, and geopolymers. A "sloped base" refers to a base whose top surface is not horizontal.

[0008] In the method for manufacturing a cement-based object, the base may have two or more flat surfaces with different inclinations. The base having two or more flat surfaces with different inclinations means that the upper surface of the base is composed of two or more flat surfaces with different inclinations. [Effects of the Invention]

[0009] According to the method for manufacturing a cement-based object of the present invention, in layered manufacturing of a cement-based material, collapse of the object during manufacturing can be suppressed regardless of the shape of the object. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a 3D printer device that uses a cement-based material. [Figure 2] 1A and 1C are diagrams showing examples of the shape of a molded object, and B and D are diagrams showing a conventional method for manufacturing a cement-based molded object. [Figure 3] FIG. 1A is a diagram showing an example of the shape of a shaped object, and FIG. 1B is a diagram showing a method for manufacturing a cement-based shaped object according to a first embodiment. [Figure 4] 1A and 1C are diagrams showing examples of shapes of a shaped object, and FIG. 1D is a diagram showing a method for manufacturing a cement-based shaped object according to the first embodiment. [Figure 5] 1A is a diagram showing an example of the shape of a shaped object, B is a diagram showing a base used in the method for manufacturing a cement-based object according to a second embodiment, and C is a diagram showing the method for manufacturing a cement-based object according to the second embodiment. [Figure 6] 10 is a mortar object produced by the method of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] First, we will briefly explain 3D printers that use cementitious materials. Figure 1 shows the configuration of a typical cementitious 3D printer. In 3D printer 10, a nozzle 12 is attached to the tip of the arm of an articulated robot 11. Cementitious material is extruded from a hopper 13 by a pressure pump 14 into a hose 15 and transported to the nozzle 12. As the robot 11 moves the nozzle 12 along a predetermined path, cementitious material 16 is discharged from the nozzle 12 onto a base 30, thereby forming an object 20 through layered manufacturing.

[0012] A first embodiment of the present invention will be described with reference to Figures 2 to 4. The method for producing a cement-based object of this embodiment is carried out using a 3D printer apparatus shown in Figure 1.

[0013] 2A and 2B, if the object 21 is a bowl-shaped object that widens upward, it can be shaped upside down. By turning it upside down, the entire wall supports the force that would otherwise collapse due to gravity, so the object will not collapse during shaping. This type of shaping method has been used in the past.

[0014] Referring to Figures 2C and 2D, even if the object 22 has an inclined cylindrical shape, it can be printed upside down as long as the upper end is approximately perpendicular to the longitudinal direction. By turning the object upside down, a shape that stands approximately vertically is printed, and it will not collapse during printing. If the height of the object is not uniform, for example, the object 22 in Figures 2C and 2D is higher on the left side and lower on the right side, the thickness of each layer can be changed by changing the nozzle movement speed within each layer while discharging the material. In Figure 2D, by slowing the nozzle movement speed on the left side and speeding it up on the right side, each layer can be made thicker on the left side and thinner on the right side. This allows the same number of layers to be stacked at all positions and the upper end to be printed in an inclined manner.

[0015] Referring to Fig. 3A, if the object 23 has an inclined cylindrical shape and the upper end is approximately horizontal, it will still be prone to collapse during modeling even if it is turned upside down. In this embodiment, in such a case, referring to Fig. 3B, additive manufacturing is performed on an inclined base 31, thereby preventing collapse during modeling. A tilted base, more precisely, means that the upper surface 32 of the base is not horizontal.

[0016] Although it depends on the physical properties of the material used, if the overhang angle (θ in Figure 3A) of the object exceeds 20 degrees, the probability of collapse during printing increases significantly. Therefore, it is preferable to tilt the base and set the overhang angle of the object to 20 degrees or less. Furthermore, in an experiment conducted by the inventors to print a pot-shaped object with a square base measuring 150 mm on each side and with all four sides tapering outward as it goes up, the nozzle movement speed could be increased when the overhang angle was 15 degrees compared to when the overhang angle was 20 degrees, and could be increased even more when the overhang angle was 10 degrees. Therefore, it is preferable to tilt the base and set the overhang angle of the object to more preferably 15 degrees or less, and particularly preferably 10 degrees or less.

[0017] Furthermore, depending on the shape of the object, the top and bottom during additive manufacturing may be predetermined. For example, referring to Fig. 4A, if the object 24 is cylindrical and one end is closed with a lid 25, referring to Fig. 4B, it can be conveniently manufactured with the lid 25 facing downward, eliminating the need for a core to support the lid 25 during manufacturing. If simply reversing the top and bottom would result in a large overhang, using an inclined base 31 can reduce the overhang and prevent collapse during manufacturing.

[0018] Also, referring to Figure 4C, when forming subtle irregularities on the bottom surface 27 of the object 26, it may be possible to create more natural-looking irregularities by adjusting the nozzle speed when printing with that surface facing up. Such irregular shapes are often used in artwork, for example, to create the impression of the hem of a piece of cloth fluttering in the wind. Even with such an object, if simply turning the object upside down would result in a large overhang, referring to Figure 4D, using an inclined base 31 can reduce the overhang and prevent collapse during printing.

[0019] A second embodiment of the present invention will be described with reference to Figures 5 and 6. The method for producing a cement-based object of this embodiment is carried out using the 3D printer apparatus shown in Figure 1.

[0020] Referring to Fig. 5A, when the shape of the top end of the object 28 is composed of multiple flat surfaces 29a-29c, referring to Fig. 5B, additive manufacturing can be performed on a base 33 having two or more flat surfaces 34a-34c with different inclinations. The base having two or more flat surfaces with different inclinations means that the top surface of the base is composed of two or more flat surfaces with different inclinations. This makes it easier to manufacture an object 28 with a complex shape.

[0021] FIG. 6 shows a mortar object produced by the method of this embodiment.

[0022] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the technical concept thereof. [Explanation of symbols]

[0023] 10 3D printer equipment 11. Robot 12 nozzles 13 Hopper 14 Pressure pump 15 Hose 16 Cement-based materials 20~24, 26, 28 Modeled objects 25 Lid 27 Uneven bottom surface 29a-c Multiple planes that make up the top edge 30~31, 33 Base 32 Top of the base 34a-c Planes with different slopes on the top surface of the base θ Overhang angle

Claims

1. A method for additive manufacturing of a cement-based object by moving a nozzle that discharges a cement-based material, comprising: The cement-based object is manufactured by layering on an inclined base. A method for manufacturing cement-based objects.

2. The base has two or more planes with different inclinations. The method for producing the cement-based shaped object according to claim 1.

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