Method for manufacturing cement-based molded article

Abstract

To provide a method by which a molded article can be manufactured without interrupting discharge of a material from a nozzle and without thickening a side to be formed even in the cases where the same movement path of the nozzle cannot be used for every layer, and a planar shape of a molded article cannot be configured with a single stroke in an additive manufacturing of a cement-based material.SOLUTION: A method for additive manufacturing a cement-based molded article includes moving a nozzle that discharges a cement-based material. A planar shape of the cement-based molded article has two or more odd points (d, e, h, and i). A first route (R1) along which the nozzle moves in odd-numbered layers of the cement-based molded article is different from a second route (R2) along which the nozzle moves in even-numbered layers after the first route. A sum of the first route and the second route corresponds to the fact that the nozzle passes through every side of the planar shape twice.SELECTED DRAWING: Figure 4

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 used to create structures made of cement-based materials such as concrete. These 3D printers move a nozzle that dispenses the cement-based material, building up the material layer by layer. The nozzle typically moves along the same path for all layers. If the planar shape of the object cannot be constructed in a single stroke, the nozzle temporarily stops discharging the material, moves it to another location, and then resumes discharging. However, because the amount of material dispensed varies between when discharging is stopped and when it is resumed, it is difficult to efficiently produce high-quality objects. To address this issue, Patent Document 1 describes a method for creating a mortar structure using a 3D printer. The method divides the planar shape of the laminated portion into divided regions across the width of the laminated portion, and then moves the nozzle along a discharging path that connects the divided regions in a single stroke. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-064588 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method described in Patent Document 1 cannot be used in cases where the paths constituting the planar shape are doubled in the width direction, resulting in thick walls (sides) and limited internal space.

[0005] 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 manufacture a molded object without interrupting the discharge of material from the nozzle and without thickening the sides that are formed, even when the nozzle movement path cannot be made the same for all layers or the planar shape of the molded object cannot be constructed in a single stroke. [Means for solving the problem]

[0006] The method for manufacturing a cement-based object of the present invention is a method for layer-by-layer manufacturing of a cement-based object by moving a nozzle that discharges a cement-based material, wherein the planar shape of the cement-based object has two or more odd points, a first path that the nozzle follows in odd-numbered layers of the cement-based object is different from a second path that the nozzle follows in even-numbered layers following the first path, and the nozzle passes along all sides of the planar shape twice, taking the first path and the second path together.

[0007] Here, cementitious materials include mortar, concrete, and geopolymers. The planar shape is the shape of each layer in a planar view. An odd point is a vertex when the planar shape is represented as a graph, and generally refers to a point where the number of sides connected to the vertex is odd, but in this specification it refers to a point where the number of sides connected to the vertex is an odd number of three or more. A side refers to a line portion that makes up the planar shape, and may be a straight line or a curve. A vertex where the number of sides connected to the vertex is even is called an even point.

[0008] In one embodiment of the method for manufacturing a cement-based object of the present invention, the planar shape has two odd points, the first path and the second path each pass through all edges of the planar shape once, and the start points and end points of the first path and the second path are reversed.

[0009] In another aspect of the method for manufacturing a cement-based object of the present invention, the first path passes through a portion of the planar shape that can be drawn in one stroke, and the second path passes once over an edge that was passed through on the first path and twice over an edge that was not passed through on the first path.

[0010] In another aspect of the method for producing a cement-based shaped object, the planar shape preferably has four or more odd points. [Effects of the Invention]

[0011] According to the method for manufacturing a cement-based object of the present invention, even if the movement path of the nozzle that discharges the cement-based material cannot be made the same for all layers or the planar shape of the object cannot be constructed in a single stroke, it is possible to manufacture a cement-based object by additive manufacturing without interrupting the discharge of material from the nozzle and without thickening the sides that are formed. [Brief explanation of the drawings]

[0012] [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] A and B are examples of planar shapes that can be drawn in one stroke. [Figure 3] 10A shows a planar shape of an object formed by the method of the first embodiment, B shows a first path, and C shows a second path. [Figure 4] A: Planar shape, B: First path, C: Second path of an object formed by the method of the second embodiment. [Figure 5] 10A to 10C are diagrams illustrating a second route of the method of the second embodiment. [Figure 6] 10A to 10C are diagrams illustrating a second route of the method of the second embodiment. [Figure 7] 10 is a prototype of a mortar object produced by the method of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] First, we will briefly explain 3D printers that use cement-based materials. Figure 1 shows the configuration of a typical cement-based 3D printer. In 3D printer 10, a nozzle 12 is attached to the tip of the arm of an articulated robot 11. Cement-based material is pushed from hopper 13 into hose 15 by a pressure pump 14 and transported to nozzle 12. Additive manufacturing is performed by discharging the cement-based material from nozzle 12 while robot 11 moves nozzle 12 along a predetermined path.

[0014] If the planar shape of the object to be molded is a simple contour line with no branches, as shown in Figure 2A, the nozzle can repeat the same movement path for each layer to build up the material. Even if the planar shape has vertices (intersections) where lines intersect, as shown in Figure 2B, if all the vertices included in the planar shape are even points, there is a single-stroke path that starts from any vertex and returns to the starting point, so additive manufacturing can be achieved by the nozzle repeating the same movement path for each layer. In this case, the nozzle passes through each intersection twice, but because the material is soft immediately after being ejected, there are no problems such as the intersections being elevated or the areas around the intersections being distorted.

[0015] A first embodiment of the present invention will be described with reference to Fig. 3. The method of this embodiment involves layered manufacturing of a cement-based object by moving a nozzle that dispenses a cement-based material, and is characterized by the path of the nozzle movement during this process. The method of this embodiment can be applied to an object whose planar shape has two odd points.

[0016] Referring to Figure 3A, the planar shape of the object has two odd points d and e. Because there are two odd points, this planar shape can be drawn in one stroke. However, because there is no path that returns to the starting point in one stroke, the nozzle cannot repeat the same path in each layer without interrupting the discharge of material.

[0017] Referring to FIG. 3B, a first path R1 followed by the nozzle in the odd-numbered layers starts from one odd point d, passes through the vertices in the order cghfebad, passes through all the edges once, and returns to the other odd point e.

[0018] Referring to FIG. 3C, the second path R2 taken by the nozzle in the subsequent even-numbered layers starts from odd point e, which is the end point of the first path R1, passes through the vertices in the order fhgcdabe, passes through all the edges once, and returns to odd point d.

[0019] Because the first path R1 and the second path R2 are different, the nozzle cannot repeat the same path for each layer without interrupting the discharge of material. However, because the end point of the first path R1 and the start point of the second path R2 coincide, and the end point of the second path R2 returns to the start point of the first path R1, by repeating the set of the first path R1 and the second path R2, additive manufacturing can be performed without interrupting the discharge of material.

[0020] Note that the first path R1 and the second path R2 are not limited to those shown in Figures 3B and 3C, and may be other unicursal paths. Furthermore, the paths do not need to be the same for all odd-numbered layers; the first path R1 may be different for each layer. The same applies to even-numbered layers. Preferably, the first path R1 for all odd-numbered layers is the same path, and the second path for all even-numbered layers is the same path. This allows the appearance of a regular pattern on the exterior of the molded object, which is preferred by consumers in many applications, and also makes it easier to set paths during additive manufacturing.

[0021] Furthermore, if one end of an edge is not connected to another edge, i.e., if there is a vertex with only one connected edge, the nozzle must turn back at that vertex. However, with cement-based materials, it is difficult to instantly and accurately increase or decrease the discharge amount in line with changes in the nozzle's movement speed at the turning point, which creates the problem of distortion of the shape around the turning point. It is practically impossible to turn the nozzle back at a certain point. Therefore, if a vertex with only one connected edge exists in a planar shape, the discharge of material must be interrupted at that vertex, moved to another location, and then resumed.

[0022] A second embodiment of the present invention will be described with reference to Figures 4 to 7. The method of this embodiment involves moving a nozzle that dispenses a cementitious material to layer-by-layer manufacture a cementitious object, and is characterized by the path of nozzle movement during this process. The method of this embodiment can be applied regardless of the number of odd points in the planar shape of the object.

[0023] 4A, the plane shape of the object has four odd points d, e, h, and i. Since the number of odd points is four, this plane shape cannot be drawn in one stroke.

[0024] Referring to FIG. 4B, the first path R1 followed by the nozzle in odd-numbered layers starts from a single vertex a, passes through the vertices dchgkljifeb in order, and returns to the starting point a. The first path R1 can start from any vertex. The first path R1 may pass through any portion of the planar shape that can be drawn in one stroke. Preferably, the first path R1 is set to travel around the periphery of the planar shape, which creates a continuous line on the exterior of the molded object, which is preferred by consumers in many applications.

[0025] 4C, the second path R2 that the nozzle follows in the even-numbered layers following the first path R1 in FIG. 4B starts from the same starting point a as the first path, passes through the vertices in the order defihgkljihcdeb, and returns to the starting point a. The second path R2 passes through each edge that was passed through in the first path R1 once, and passes through each edge that was not passed through in the first path twice.

[0026] The second path R2 shown in FIG. 4C will be explained in more detail as follows. Referring to FIG. 5A, when the nozzle starts from the starting point a and reaches the vertex d, it turns left to pass through the edge de, which was not passed on the first path R1. If the nozzle proceeds to the edge dc, which was passed on the first path R1, the nozzle will later turn back at the vertex d in order to pass through the edge de twice. When the nozzle reaches the vertex e, it can be considered that the nozzle starts from the vertex e, travels around the lower part of the planar shape, and returns to the vertex e. Referring to FIG. 5B, when the nozzle reaches the vertex i, it also turns right to pass through the edge ih, which was not passed on the first path R1. In this way, the second path R2 finally returns to the starting point a, as shown in FIG. 5C. In this way, the second path R2 followed by the nozzle on the even-numbered layers returns to the starting point by passing through a part of the edge at the same height as the first path R1.

[0027] Even when the planar shape is more complex, the second route can be determined in a similar manner based on the first route. Since the second route passes twice over edges that were not passed over on the first route, if a graph is created by doubling these edges, all of the graph's vertices will be even, as shown in Figure 6A. This planar shape can be drawn in one stroke, and a one-stroke path can be found using a known method. If the found path includes a turnaround (Figure 6B), the double lines (de) do not connect at the turnaround point (d), but are modified so that each of the double lines connects to other edges (da, dc) at the turnaround point. The original path is then modified so that it traces the portion of the path that passes through the vertices (c, f, g-l) beyond the turnaround point (d) and returns to vertex e in one stroke in the opposite direction (Figure 6C).

[0028] In the above description, even point a is set as the starting point of the first route R1, but an odd point may also be set as the starting point of the first route. For example, if the starting point of the first route R1 is odd point d, the first route may be set to return to the starting point d, or to another odd point, such as odd point e. Even in this case, the second route R2 can be set to pass through each edge passed by the first route R1 once and pass through each edge not passed by the first route twice.

[0029] According to the method of this embodiment, the second path R passes through each edge passed through by the first path R1 once and passes through each edge not passed through by the first path twice. Thus, when the first path R1 and the second path R2 are combined, the nozzle passes through each edge of the planar shape twice, resulting in the same height of material being deposited over the entire planar shape. By repeating the first path R1 and the second path R2, additive manufacturing can be performed without interrupting the material discharge. It should be noted that the first path R1 does not need to be the same for all odd-numbered layers; even if the first path R1 differs depending on the layer, the second path can be determined according to each first path.

[0030] The method of this embodiment can be applied regardless of the number of odd points contained in the planar shape. However, if all vertices are even points, additive manufacturing can be performed by repeating the same movement path for each layer using conventional methods, and if the number of odd points is two, the method of the first embodiment can also be used. Therefore, the method of this embodiment is particularly advantageous when the planar shape cannot be drawn in one stroke and the number of odd points is four or more. Figure 7 shows a photograph of a prototype mortar object having the planar shape of Figure 4A manufactured using the method of this embodiment. [Explanation of symbols]

[0031] 10 3D printer equipment 11. Robot 12 nozzles 13 Hopper 14 Pressure pump 15 Hose R1 1st pathway R2 Second pathway a~l vertex

Claims

1. A method for additive manufacturing of a cement-based object by moving a nozzle that discharges a cement-based material, comprising: the planar shape of the cement-based object has two or more odd points; a first path followed by the nozzle in odd-numbered layers of the cement-based object is different from a second path followed by the nozzle in even-numbered layers following the first path, and the nozzle passes through every side of the planar shape twice by combining the first path and the second path. A method for manufacturing cement-based objects.

2. the planar shape has two odd points, the first path and the second path each pass through every edge of the planar shape once, The start point and the end point of the first route and the second route are reversed. The method for producing the cement-based shaped object according to claim 1.

3. the first path passes through a portion of the planar shape that can be drawn in one stroke, the second path passes once over an edge that was passed over in the first path, and passes twice over an edge that was not passed over in the first path; The method for producing the cement-based shaped object according to claim 1.

4. The planar shape has four or more odd points. The method for producing a cement-based shaped object according to claim 3 .

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