3D modeling system

Abstract

To solve a striped pattern between layers when a cement-based material is laminated to form a three-dimensional molded article.SOLUTION: A three-dimensional molding system laminates a cement-based material to form a three-dimensional molded article. This three-dimensional molding system comprises: a nozzle 13 discharging the cement-based material; and a finishing device 3 fitted to the nozzle 13 and finishing the surface of the cement-based material discharged from the nozzle 13. The finishing device 3 has trowels 31A, 31B movable so that the tip part comes to a position advanced in the discharge direction of the cement-based material.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional modeling system for forming a three-dimensional object by layering cement-based materials. [Background technology]

[0002] In recent years, various techniques have been proposed for applying 3D printer technology to form objects such as buildings and structures using cement-based materials such as concrete and mortar (see, for example, Patent Documents 1 and 2). In an example of forming such objects using 3D printer technology, the three-dimensional shape of the object to be formed is first modeled using a computer. Next, two-dimensional data divided into multiple layers is generated from the modeled three-dimensional data. The cementitious material is then supplied from a pump to a movable supply head, and the cementitious material is discharged from the nozzle of the supply head based on the two-dimensional data of each layer to form the two-dimensional shape of each layer.Then, on top of the formed two-dimensional shape of the layer, cementitious material is layered one by one based on the two-dimensional data of the subsequent layer, thereby forming a three-dimensional object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-122539 [Patent Document 2] Japanese Patent Application Publication No. 2018-140906 Summary of the Invention [Problem to be solved by the invention]

[0004] The 3D printers described in Patent Documents 1 and 2, which form models by layering cement-based materials, have larger nozzle diameters than 3D printers that use materials such as resin, resulting in thicker layers. Furthermore, because the material is layered in a soft state, the cross-sectional shape of the layers is prone to deformation. For this reason, when the cross-section of a layer is viewed enlarged, it resembles a stack of ellipses, and unevenness is likely to occur between layers (see Figure 5 of Patent Document 1 and Figure 3 of Patent Document 2). The presence of such unevenness (striped patterns) not only raises concerns about aesthetic impacts such as design restrictions and dirt adhesion, but also raises concerns about reduced durability and structural strength of the object if the boundaries between layers form discontinuous surfaces. An object of the present invention is to eliminate striped patterns between layers when a three-dimensional object is formed by layering cement-based materials. [Means for solving the problem]

[0005] The present invention, which solves the above-mentioned problems, provides a three-dimensional modeling system for forming a three-dimensional object by layering a cement-based material. The three-dimensional modeling system includes: a nozzle for discharging the cement-based material; a nozzle support device that movably supports the nozzle; and a finishing device attached to the nozzle for finishing the surface of the cementitious material discharged from the nozzle. The finishing device has a trowel that can be moved so that its tip is positioned at a position advanced in the direction of discharge of the cementitious material. The finishing device has a rotation mechanism that rotates the trowel relative to the nozzle around the central axis of the nozzle, and controls the operation of the rotation mechanism so that the trowel is positioned to the side of a straight line that passes through the central axis of the nozzle and is along the direction of movement of the nozzle. . In the present invention, the trowel contacts the surface of the cementitious material as it advances, and the nozzle advances in this state to finish the surface. This eliminates stripes between layers and results in a smooth finished surface. By performing surface finishing, the formation of discontinuous surfaces between layers is suppressed, which is expected to improve the durability of the molded object. It is also expected to improve the aesthetic appearance of the molded object and prevent a decrease in structural strength. As described above, according to the present invention, when a three-dimensional object is formed by layering cement-based materials, striped patterns between layers can be eliminated. The trowel may be configured to be able to advance in the direction of discharging the cementitious material and to retreat in the direction opposite to the direction of discharging the cementitious material, in which case the trowel may be configured to move linearly so that the tip of the trowel reaches a position advanced in the direction of discharging the cementitious material. This configuration allows the iron to be rotated independently of the nozzle, making it possible to adjust the circumferential position of the iron around the central axis of the nozzle, i.e., the orientation of the iron, using the rotation mechanism without rotating the nozzle itself.

[0006] It is also preferable that the three-dimensional positional information of the trowel relative to the object during the formation of the object is used to determine whether the surface of the cementitious material that the trowel comes into contact with when it is advanced is the surface to be finished, and in this case, the movement of the trowel is controlled based on the determination result. In this configuration, by using information about the three-dimensional position of the trowel relative to the shaped object when the shaped object is being formed, the position of the trowel in the advancing and retreating directions can be determined efficiently. It is also preferable that the iron be positioned to the side of a straight line that passes through the central axis of the nozzle and extends in the direction of travel of the nozzle. In this configuration, the surface of the cementitious material can be finished by appropriately contacting the trowel from the side with the surface.

[0007] Ma The printing system preferably further comprises a buffering device and a control unit. The buffering device temporarily stores pulse train data based on a code described in two-dimensional data for each layer obtained from the three-dimensional data of the shaped object. The control unit analyzes the moving direction of the nozzle from the pulse train data stored in the buffering device. The control unit also transmits a control signal to the rotation mechanism based on the analyzed moving direction of the nozzle at the same timing as the pulse train data for moving the nozzle. In this configuration, by temporarily storing the pulse train data in the buffering device, time can be secured to analyze the direction of travel of the nozzle, allowing the cementitious material to be discharged from the nozzle and the surface of the cementitious material to be appropriately finished with the trowel at the same time.

[0008] The rotation mechanism preferably includes an outer stator, an outer rotor, and a motor. Here, the outer stator is fixed to the nozzle. The outer rotor is disposed radially outside the outer stator via a bearing so as to be rotatable together with the iron about the central axis of the nozzle. The servo motor rotates the outer rotor via a power transmission means. The power transmission means preferably includes a first pulley fixed to the outer rotor and a second pulley connected to the first pulley via a belt so as to transmit power. In this case, the servo motor rotates the second pulley. With this configuration, the iron can be rotated reliably and quickly with a simple configuration. The finishing device preferably includes a compression spring that biases the trowel in the direction of advancing the trowel, and a servo motor that rewinds the trowel via a filament-like member in the direction of retraction of the trowel. With this configuration, the iron can be reliably and quickly advanced and retreated with a simple configuration.

[0009] Furthermore, it is preferable that the finishing portion of the trowel, which contacts the surface of the cementitious material to form a finished surface, is positioned rearward of the center of the nozzle in the direction of travel of the nozzle. With this configuration, the finishing portion of the trowel can be reliably brought into contact with the surface of the cementitious material after it has been discharged from the nozzle, thereby enabling finishing of the surface. [Effects of the Invention]

[0010] According to the present invention, when a three-dimensional object is formed by layering cement-based materials, striped patterns between layers can be eliminated. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an overview of a three-dimensional fabrication system according to an embodiment of the present invention. [Figure 2]FIG. 2 is an enlarged cross-sectional view of the nozzle device shown in FIG. [Figure 3] FIG. 2 is an enlarged perspective view of the finishing device shown in FIG. 1 together with the nozzle. [Figure 4] 4(a) is a front view of FIG. 3, FIG. 4(b) is a right side view of FIG. 4(a), and FIG. 4(c) is a bottom view of FIG. 4(a). [Figure 5] FIG. 4(c) is a cross-sectional view taken along line VV of FIG. [Figure 6] 10 is a flowchart showing the operation of the three-dimensional fabrication system. [Figure 7] FIG. 10 is a schematic plan view for explaining control of the direction of the iron. [Figure 8] 8(a) and 8(b) are schematic front views for explaining the control of the advance / retract movement of the iron. [Figure 9] 9(a) to 9(d) are schematic diagrams for explaining more specifically the control of the advance / retract movement of the iron. [Figure 10] Figure 10(a) is a diagram showing the layering area, which is the area where the deposition layer is actually placed, Figure 10(b) is a diagram showing the deposition area with the discharge range filled in, and Figure 10(c) is a diagram showing the deposition layer data. [Figure 11] FIG. 10 is a diagram for explaining a method for calculating the direction of travel of the nozzle. [Figure 12] FIG. 10 is a diagram for explaining a method for calculating the position of the iron. [Figure 13] Figure 13(a) shows the iron placement layer data created by filling in the area corresponding to the left iron, and Figure 13(b) shows the iron placement layer data created by filling in the area corresponding to the right iron. [Figure 14] Figure 14(a) shows a composite image obtained by combining the trowel placement layer data corresponding to the left trowel with the deposition layer data, and Figure 14(b) shows a composite image obtained by combining the trowel placement layer data corresponding to the right trowel with the deposition layer data. [Figure 15] FIG. 10 is a schematic side view illustrating a soldering iron part according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or similar components are designated by the same reference numerals, and redundant descriptions will be omitted. In addition, the size and shape of components may be exaggerated or distorted for ease of explanation.

[0013] 1 is a perspective view showing an overview of a three-dimensional modeling system 100 according to an embodiment of the present invention. The three-dimensional modeling system 100 is a so-called 3D printer that generates two-dimensional shapes by extruding a cement-based material from a nozzle device 1 and stacks these in the height direction to form a three-dimensional object. Examples of cement-based materials include concrete, mortar, and cement paste.

[0014] As shown in FIG. 1, the three-dimensional modeling system 100 includes a nozzle device 1, a nozzle support device 2, a finishing device 3, and a control device 5. The nozzle device 1 has a nozzle 13 (see FIG. 2, the same applies below) at its tip (lower end) that discharges the cementitious material C. The nozzle device 1 moves in a plane while discharging the cementitious material C from the nozzle 13. After forming a predetermined two-dimensional shape through its planar movement, the nozzle device 1 moves upward. In other words, the nozzle device 1 is supported by the nozzle support device 2 so as to be movable three-dimensionally. The nozzle device 1 is connected to the control device 5, and discharges the cementitious material C in response to signals from the control device 5.

[0015] The nozzle support device 2 moves the nozzle device 1 in a plane along the X-axis and Y-axis, and moves it up and down along the Z-axis. In other words, the three-dimensional modeling system 100 is capable of forming a three-dimensional object by three-dimensionally moving the nozzle device 1 via the nozzle support device 2. The nozzle support device 2 of this embodiment includes an X-axis rail 21 arranged along the X-axis, a pair of Y-axis rails 22 arranged along the Y-axis, and a Z-axis column 23 erected along the Z-axis. The X-axis rail 21 slidably supports the nozzle device 1. The nozzle device 1 moves in the X-axis direction by moving along the X-axis rail 21. The X-axis rail 21 is slidably supported by the pair of Y-axis rails 22. The X-axis rail 21 slides along the Y-axis rail 22, causing the nozzle device 1 to move in the Y-axis direction. The nozzle device 1 moves along the X-axis rail 21 and the Y-axis rail 22 at the same time, causing the nozzle device 1 to move diagonally. That is, the nozzle device 1 can be freely moved in a plane by the X-axis rail 21 and the Y-axis rail 22. Furthermore, the Y-axis rail 22 is supported by the Z-axis pillar 23 so that it can move up and down. When the Y-axis rail 22 moves along the Z-axis pillar 23, the nozzle device 1 moves up and down. The nozzle support device 2 is connected to the control device 5, and moves the nozzle device 1 in a predetermined direction in response to a signal sent from the control device 5.

[0016] Fig. 2 is an enlarged cross-sectional view of the nozzle device 1 shown in Fig. 1. As shown in Fig. 2, the nozzle device 1 includes a cylinder part 11 with a central axis extending in the vertical direction, a screw conveying part 12 in which a screw 14 is housed, and a nozzle 13 detachably attached to the tip of the screw conveying part 12. A storage chamber 11a is provided in the upper part of the cylinder section 11. The storage chamber 11a has an upper part formed in the shape of a large-diameter, approximately hollow cylinder, and its lower part formed in the shape of a hollow, approximately inverted truncated cone whose diameter decreases as it goes downward. Furthermore, the connecting part with the screw conveying section 12 below is formed in the shape of a small-diameter hollow cylinder. The screw conveying section 12 is formed in the shape of a cylinder with an inner diameter approximately the same as that of the small-diameter part at the bottom of the cylinder section 11. The nozzle 13 is funnel-shaped, and a discharge port 13a is provided at its tip facing downward.

[0017] A supply pipe 61 is connected to the cylinder portion 11 at the upper side of the storage chamber 11a. The supply pipe 61 is connected to a hopper 63 serving as a storage portion via a pump 62. Cementitious material C mixed to a predetermined mix is ​​stored in the hopper 63. When the pump 62 is operated, the cementitious material C stored in the hopper 63 is supplied to the cylinder portion 11.

[0018] A drive motor 15 is provided on the upper part of the nozzle device 1. A rotary shaft 16 is connected to the output shaft of the drive motor 15 via a coupling (not shown) so as to be able to transmit a rotational driving force. A stirring blade 17 serving as a stirring member made up of a combination of spiral wires is attached to the rotary shaft 16 at a position within the storage chamber 11a of the cylinder portion 11.

[0019] A screw 14, which has a helical male thread formed on its outer periphery, is fixed to the lower end of the rotating shaft 16 in a position that hangs down coaxially with the rotating shaft 16. When the drive motor 15 is driven in the forward direction to rotate the screw 14 at a given steady speed, the cementitious material C in the storage chamber 11a is pushed out by the helical male thread toward the tip of the nozzle 13. This allows the cementitious material C in the cylinder portion 11 to be pressure-fed in a fixed amount toward the tip of the screw conveying portion 12.

[0020] Fig. 3 is an enlarged perspective view showing the finishing device 3 shown in Fig. 1 together with the nozzle 13. Fig. 4(a) is a front view of Fig. 3, Fig. 4(b) is a right side view of Fig. 4(a), and Fig. 4(c) is a bottom view of Fig. 4(a). Fig. 5 is a cross-sectional view taken along line VV of Fig. 4(c). As shown in FIGS. 3 to 5, the finishing device 3 is attached to the nozzle 13. The finishing device 3 is a device that finishes the surface of the cementitious material C discharged from the discharge port 13a of the nozzle 13. The finishing device 3 includes trowel units 30A, 30B and a rotation mechanism unit 40. Trowel sections 30A, 30B have trowels 31A, 31B that come into contact when finishing the surface of cementitious material C discharged from nozzle 13. Trowels 31A, 31B are configured to be movable so that their tips are positioned to advance in the discharge direction (downward in FIG. 5) of cementitious material C. In this embodiment, specifically, trowels 31A, 31B are configured to be able to advance in the discharge direction of the cementitious material and retract in the direction opposite to the discharge direction (upward in FIG. 5).

[0021] The rotation mechanism 40 rotates the irons 31A and 31B relative to the nozzle 13 around the central axis CL of the nozzle 13. The rotation mechanism 40 includes an outer stator 41, outer rotors 42A and 42B, and a servo motor 45. The outer stator 41 is fixed to the nozzle 13 via a plate 47. The outer stator 41 has a generally cylindrical shape and is fixedly disposed radially outward from the nozzle 13. The outer rotors 42A and 42B are arranged side by side in the direction of the central axis CL of the nozzle 13 and are fixed to each other. The outer rotors 42A and 42B are disposed radially outward from the outer stator 41 via bearings 48 (see FIG. 5) so as to be rotatable about the central axis CL of the nozzle 13. An O-ring 49A is fitted between the outer rotor 42A and the outer stator 41, and an O-ring 49B is fitted between the outer rotor 42B and the outer stator 41. The servo motor 45 rotates the outer rotors 42A and 42B via power transmission means. The power transmission means has a first pulley 43 fixed to the outer rotor 42A and a second pulley 44 connected to the first pulley 43 via a belt 46 so that power can be transmitted. In this case, the servo motor 45 rotates the second pulley 44. In this embodiment, toothed pulleys are used as the first pulley 43 and the second pulley 44, and a toothed belt is used as the belt 46. In this embodiment, a belt mechanism (first pulley 43, second pulley 44, and belt 46) is used as the power transmission means, but the present invention is not limited to this and a gear mechanism, for example, may be used. Specifically, the power transmission means may have a first gear fixed to the outer rotor 42A and a second gear meshing with the first gear (not shown). In this case, the servo motor 45 rotates and drives the second gear. In place of the servo motor 45, a stepping motor or a combination of a DC motor and an encoder may be used.

[0022] The iron sections 30A, 30B include compression springs 32A, 32B (see FIG. 5) and servo motors 33A, 33B. The compression springs 32A, 32B bias the irons 31A, 31B in the direction of advancement of the irons 31A, 31B. The servo motors 33A, 33B rotate spools 331A, 331B to rewind the irons 31A, 31B in the direction of retreat of the irons 31A, 31B via the filament members 34A, 34B. The servo motors 33A, 33B are fixed to positions 180 degrees opposite each other on the outer peripheral surface of the outer rotor 42A. For example, high-strength PE line is used as the filament members 34A, 34B.

[0023] 3, a trowel stand 35 that supports the trowels 31A and 31B so that they can slide up and down is fixed to the tip (lower end) of the outer rotor 42B. The trowel stand 35 has a first circular plate portion 36 fixed to the outer rotor 42B, a second circular plate portion 37 disposed below the first circular plate portion 35a, and an intermediate portion 38 connecting the first circular plate portion 36 and the second circular plate portion 37.

[0024] As shown in Fig. 5, a pair of rods 36a extending downward from the underside of the first circular plate 36 is provided on the underside of the first circular plate 36. Also, as shown in Fig. 3, guide rods 36b (see Fig. 3) extending downward from the underside of the first circular plate 36 are provided on both sides of the rod 36a. The irons 31A and 31B are formed with central holes 311A ​​and 311B into which the rods 36a are inserted, and guide holes (not shown) into which the guide rods 36b are inserted. The second circular plate 37 is formed with a pair of openings 37a through which the irons 31A and 31B are inserted in the vertical direction. Compression springs 32A and 32B are attached between the tip of rod 36a and the bottom of central holes 311A ​​and 311B. Rod 36a has a through-hole 36c formed in the vertical direction, through which thread-like members 34A and 34B are inserted. Thread-like members 34A and 34B extending from spools 331A and 331B pass through through-hole 36c and are connected to the bottom of central holes 311A ​​and 311B. This allows irons 31A and 31B to move forward and backward downward and upward.

[0025] As shown in FIGS. 3 and 4, the trowels 31A and 31B have a substantially rectangular parallelepiped shape. As shown in FIG. 4(c), the surfaces of the trowels 31A and 31B facing the central axis CL of the nozzle 13 have introduction sections 312A and 312B and finishing sections 313A and 313B, respectively. The introduction sections 312A and 312B are positioned so as to contact the outer peripheral surface of the tip of the nozzle 13. The finishing sections 313A and 313B are positioned closer to a line L passing through the central axis CL of the nozzle 13 and along the direction of travel of the nozzle 13 than the introduction sections 312A and 312B. In FIG. 4(c), the direction of travel of the nozzle 13 is the upward direction of the page. The finishing sections 313A and 313B of the trowels 31A and 31B contact the surface of the cementitious material C to form a finished surface. The finishing sections 313A and 313B are located rearward of the introduction sections 312A and 312B and rearward of the center of the nozzle 13 in the traveling direction of the nozzle 13.

[0026] As shown in FIG. 1, the control device 5 includes a computer 51, a 3D printer control board 52, a buffering device 53, and a control unit 54. The computer 51 is, for example, a personal computer having a CPU and a storage device. The storage device of the computer 51 stores two-dimensional data for each layer obtained from the three-dimensional shape data. This two-dimensional data contains various codes (commands) such as G-code. The control unit 54 may be, for example, an FPGA (Field Programmable Gate Array) capable of high-speed processing. Note that if a stepping motor is used instead of the servo motor 45 and commands are added to the G-code, the buffering device 53 and control unit 54 in FIG. 1 can be omitted.

[0027] Next, the operation of the 3D modeling system 100 will be described with reference to FIG. As shown in FIG. 6, when the computer 51 of the control device 5 receives an instruction to start operation, the 3D printer control board 52 acquires two-dimensional data for each layer from the storage device of the computer 51 (step S1). The 3D printer control board 52 generates pulse train data to be sent to the nozzle device 1, the nozzle support device 2, and the finishing device 3 based on the code written in the two-dimensional data. The buffering device 53 then temporarily stores the pulse train data sent from the 3D printer control board 52 (step S2). The control unit 54 then analyzes the moving direction of the nozzle 13 from the pulse train data stored in the buffering device 53 (step S3). For example, the moving direction of the nozzle 13 is determined to be the linear direction from the previous position relative to the current position of the center of the outlet 13a of the nozzle 13 to the destination position. The control unit 54 then transmits a control signal to the rotation mechanism 40 based on the analyzed moving direction of the nozzle 13 at the same timing as the pulse train data for moving the nozzle 13 (step S4).

[0028] Next, the nozzle device 1, nozzle support device 2, and finishing device 3 are operated based on the control signal and pulse train data, thereby forming a model layer by layer (step S5). Steps S1 to S5 are then repeated to form a three-dimensional model. In this embodiment, pulse train data for the extruder (extrusion information for the cementitious material C) is also buffered at the same time, and this pulse train data can also be used for feedback control of the discharge rate from the nozzle 13.

[0029] Fig. 7 is a schematic plan view for explaining the control of the orientation of the irons 31A and 31B. As shown by the solid line in Fig. 7, when the nozzle 13 moves leftward on the paper, the operation of the rotation mechanism 40 is controlled so that the irons 31A and 31B are positioned to the side of a line L1 that passes through the central axis CL of the nozzle 13 and extends along the direction of movement of the nozzle 13. As shown by the two-dot chain line in Fig. 7, when the nozzle 13 moves upward on the paper, the operation of the rotation mechanism 40 is controlled so that the irons 31A and 31B are positioned to the side of a line L2 that passes through the central axis CL of the nozzle 13 and extends along the direction of movement of the nozzle 13.

[0030] 8(a) and 8(b) are schematic front views for explaining the control of the advancing and retreating movements of the trowels 31A and 31B. The model 65 shown in FIG. 8 illustrates an example in which long components extending perpendicular to the plane of the drawing are arranged in three rows per layer, and these are stacked into three layers. In FIG. 8(a), the outlet 13a of the nozzle 13 is located at the right end of the third layer from the bottom, and the nozzle 13 moves toward the depth of the plane of the drawing while discharging cementitious material C in the direction indicated by the outline arrow. In this case, the right surface of the cementitious material C discharged at the right end of the third layer contacts the outer surface of the model 65 and is therefore determined to be the surface to be finished. Therefore, the trowel 31A on the right side in the direction of movement of the nozzle 13 is controlled to move to the advancing position. When the trowel 31A is in the advancing position, the tip (lower end) of the trowel 31A is positioned so as to abut against the side surface of the layer immediately below the layer to be formed (here, the second layer from the bottom). In Figure 8(b), the discharge port 13a of the nozzle 13 is located in the center of the third layer. In this case, the left and right surfaces of the cementitious material C discharged into the center of the third layer will hit the inside of the model 65, so it is determined that these are not surfaces to be finished, and the trowels 31A and 31B are controlled to move to their retracted positions. Here, if the trowel 31A were to advance in Figure 8(b), it would come into contact with the already formed model 65, which is inappropriate.

[0031] 9(a) to 9(d) are schematic diagrams for more specifically explaining the control of the advancing and retreating movements of the trowels 31A and 31B. FIG. 9(a) is a schematic front view of the completed object 65. FIG. 9(b) is a schematic plan view showing the first layer from the bottom (lower layer) of the object 65 in the process of being formed. FIG. 9(c) is a schematic plan view showing the second layer (upper layer) of the object 65 in the process of being formed, with the trowels 31A and 31B in the advanced position. FIG. 9(d) is a schematic perspective view of the completed object 65. The object 65 shown in FIG. 9 is an example in which long, horizontally extending component members A1 to A6 are arranged in three rows per layer and stacked in two layers.

[0032] As shown in FIG. 9(b), when forming the first layer (lower layer) of the object 65, the outlet 13a of the nozzle 13 moves, for example, in the direction indicated by the arrow. At this time, the forming target is the bottom layer (components A1 to A3) of the object 65, so the irons 31A and 31B are controlled to move to the retracted positions. As shown in FIG. 9(c), when forming the second layer (upper layer) of the object 65, the outlet 13a of the nozzle 13 moves, for example, in the direction indicated by the arrow. At this time, the forming target is the top layer (components A4 to A6) of the object 65, so the advance / retract movement of the irons 31A and 31B is controlled.

[0033] In this embodiment, based on the three-dimensional position information of the trowels 31A and 31B relative to the shaped object 65 during the formation of the shaped object 65, it is determined whether the surface of the cementitious material C that the trowels 31A and 31B will come into contact with when advancing is the surface to be finished. Specifically, if the surface of the cementitious material C that the trowels 31A and 31B come into contact with when advancing hits the outer surface of the shaped object 65, it is determined that the surface is the surface to be finished. Therefore, as shown in FIG. 9(c), when forming the component A4 and the connection portion between the component A4 and the component A5, the trowel 31A is controlled to be in the advanced position and the trowel 31B is controlled to be in the retracted position. When forming the component A5 and the connection portion between the component A5 and the component A6, and when forming the component A6, the trowel 31A is controlled to be in the retracted position and the trowel 31B is controlled to be in the advanced position.

[0034] Next, with reference to Figures 10 to 13, we will explain how to determine whether the surface of the cementitious material C that comes into contact with the trowels 31A and 31B when they are advanced is the surface to be finished, and how to determine the advancement and retreat movements of the trowels 31A and 31B. 1. Preparation The three-dimensional shape data of the model 65 is converted into two-dimensional data (NC program) in which G-code is written using a slicer.

[0035] 2. Creation of sedimentary layer data 80 (see Figure 10(c)) (1) Initialization of sedimentary layer data 80 FIG. 10(a) shows a layered area 70, which is the area where the deposition layer is actually placed. Here, the deposition layer is composed of an outer layer 71 and an inner layer 72. A bitmap file is then created with a pixel count corresponding to the deposition area 70. Here, the RGB data for each pixel is all set to zero. For example, consider a case where the deposition area 70 is 500 mm x 500 mm (width W1 x height H1) and the spatial resolution is 0.1 mm. In this case, a bitmap file is created in which the number of horizontal pixels W2 and the number of vertical pixels H2 are both 500 mm ÷ 0.1 mm = 5,000 pixels. This bitmap file becomes the initialized deposition layer data 80. (2) G-code reading The G-code output by the slicer is read line by line. The read coordinates become the coordinates of the destination. In doing so, only linear interpolation G-code (commands) that are a set of X-coordinate, Y-coordinate, and data (extruder) of the rotation angle of the discharge motor (drive motor 15) are used. In other words, commands that only involve movement or only discharge motor rotation are ignored. The G code for linear interpolation is, for example, G01 X10.0 Y10.0 A500, where G01 is linear interpolation, X is the X coordinate, Y is the Y coordinate, and A is the discharge motor rotation angle.

[0036] (3) Creating a moving path for the center of the nozzle 13 10(b), the equation of a line representing the movement path is calculated from the X and Y coordinates of the current position P1 and the X and Y coordinates of the destination position P2, and the line is divided appropriately to calculate the coordinates of each line. The calculated coordinates become the movement path of the center position of the nozzle 13. (4) Filling in the discharge range (discharge port diameter) 10(b), a circle (discharge port diameter) is assumed to be centered on the center position of the nozzle 13, and the pixels inside the circle are filled in as the deposition area 73. Here, the RGB data of each pixel in the deposition area 73 is set to (red, green, blue) = (100, 0, 0).

[0037] (5) Repeat steps (2) to (4) until processing for one layer is complete. This creates deposition layer data 80, as shown in FIG. 10(c). The deposition layer data 80 has a base portion 81 consisting of pixels whose RGB data are all zero, and a deposition fill portion 82 consisting of filled pixels. Note that in this embodiment, only the red portion of the RGB data is used, so grayscale data can also be used instead of the RGB data. It is also possible to make the determination using array data instead of image file data. (6) Once processing for one layer is complete, save the file (e.g., layer001.bmp, layer002.bmp). (7) Repeat steps (1) and (5) until all layers have been processed.

[0038] 3. Deciding on advance / retraction movement of trowels 31A and 31B (1) Reading the center position of nozzle 13 The G-code output by the slicer is read in three lines at a time. At that time, only the linear interpolation G-code (command) that contains a set of data for the X-coordinate, Y-coordinate, and discharge motor rotation angle is used. The first line is the previous nozzle 13 center position (X0, Y0), the second line is the current position (X1, Y1), and the third line is the destination position (X2, Y2). (2) Calculation of the direction of travel θ of the nozzle 13 11, the linear direction from the previous position (X0, Y0) relative to the current position (X1, Y1) of the center of the nozzle 13 to the destination position (X2, Y2) is set as the moving direction θ of the nozzle 13 at the current position. That is, the moving direction θ of the nozzle 13 at the current position (X1, Y1) is calculated from equation (1).

[0039]

number

[0040] (3) Calculation of the positions of the irons 31A and 31B 12, the positions of the left and right irons 31A and 31B are calculated from the current position (X1, Y1) of the center of the nozzle 13 and the direction of travel θ. Here, it is assumed that the relative positional relationship between the center of the nozzle 13 and the left and right irons 31A and 31B is known in advance.

[0041] (4) Creating soldering iron placement layer data 90A and 90B A bitmap file with the same number of pixels as the deposition layer data 80 shown in Figure 10(c) is created. Here, the RGB data for each pixel is set to all zeros. Next, the areas corresponding to the trowels 31A and 31B are filled in. Here, the RGB data for the filled pixels is set to (red, green, blue) = (100, 0, 0). Separate files are created for the left trowel 31B and the right trowel 31A as viewed in the direction of travel. Figure 13(a) shows trowel arrangement layer data 90B created by filling in the area corresponding to the left trowel 31B. The trowel arrangement layer data 90B has a base portion 91 consisting of pixels with RGB data of all zeros and a trowel fill portion 92B consisting of filled pixels. Figure 13(b) shows trowel arrangement layer data 90A created by filling in the area corresponding to the right trowel 31A. The trowel placement layer data 90A has an unpainted portion 91 made up of pixels whose RGB data are all zero, and a trowel filled portion 92A made up of filled pixels.

[0042] (5) Determine whether the surface needs to be finished (current layer) As shown in Figures 14(a) and 14(b), composite images 80A and 80B are created by adding (combining) the bitmap files of trowel placement layer data 90A and 90B and deposition layer data 80 pixel by pixel. Composite image 80A has a base area 81, a deposition fill area 82, and a trowel fill area 92A. Here, trowel fill area 92A overlaps deposition fill area 82. Composite image 80B has a base area 81, a deposition fill area 82, and a trowel fill area 92B. By examining the pixel values ​​of composite images 80A and 80B, the overlap between trowel fill areas 92A and 92B and deposition fill area 82 can be determined as follows:

[0043] That is, if the values ​​of all pixels are red≦100 (green and blue are zero), it is determined that there is no overlap. On the other hand, if there is a pixel (or a predetermined number of pixels) where red=200 (or red>100), it is determined that there is overlap. If it is determined that there is no overlap, the surface of the cementitious material C that comes into contact with the trowels 31A and 31B when they advance is determined to be the surface to be finished. (6) Determine whether the surface needs to be finished (the layer below) The same process as (5) is carried out for the data of the next lower depositional layer.

[0044] (7) Correction of 2D data (NC program) Based on the result of the determination as to whether or not the surface is to be finished, the two-dimensional data is modified so as to add commands for controlling the advance / retract movement of the trowels 31A and 31B. That is, if both the current layer and the layer immediately below have no overlap, the trowels 31A and 31B are determined to be in the advanced position (with finishing). On the other hand, if the current layer or the layer immediately below has an overlap, the trowels 31A and 31B are determined to be in the retreated position (without finishing). This determination is made separately for the right trowel 31A and the left trowel 31B. (8) Repeat steps (1) to (7) until processing for one layer is completed. (9) Repeat (8) until all layers have been processed. Such correction of the two-dimensional data is efficiently performed by the computer 51 of the control device 5 executing a predetermined program, but it can also be performed manually. In addition, when a stepping motor is used instead of the servo motor 45, the direction of travel θ of the nozzle 13 is analyzed in advance, and two-dimensional data is used that has been modified so that information on the rotation angle of the rotation mechanism unit 40 based on the analyzed direction of travel θ of the nozzle 13 is added to the G-code. Then, based on the corrected two-dimensional data, the cementitious material C is discharged from the nozzle 13 and the advancement and retreat of the trowels 31A and 31B is controlled, thereby forming a three-dimensional object with a finished surface.

[0045] As described above, the three-dimensional modeling system 100 of this embodiment includes the nozzle 13 that discharges the cementitious material C, and the finishing device 3 that is attached to the nozzle 13 and finishes the surface of the cementitious material C discharged from the nozzle 13. The finishing device 3 has trowels 31A, 31B that are movable so that their tips are positioned in the direction in which the cementitious material C is discharged. In this embodiment, when the trowels 31A, 31B advance, the trowels 31A, 31B come into contact with the surface of the cementitious material C, and the nozzle 13 advances in this state to finish the surface. This eliminates stripes between layers, resulting in a smooth finished surface. By performing surface finishing, the formation of discontinuous surfaces between layers is suppressed, which is expected to improve the durability of the molded object. Furthermore, it is expected that the aesthetic appearance of the molded object will be improved and a decrease in structural strength will be suppressed. As described above, according to this embodiment, when a three-dimensional object is formed by layering the cementitious material C, it is possible to eliminate striped patterns between layers. In this embodiment, trowels 31A and 31B can be advanced in the direction of discharging the cementitious material and retracted in the opposite direction to the direction of discharging. In this configuration, by moving trowels 31A and 31B in a linear direction, the tips of trowels 31A and 31B can be positioned at the positions advanced in the direction of discharging the cementitious material.

[0046] In this embodiment, whether the surface of the cementitious material C that the trowels 31A, 31B contact when advancing is determined based on the three-dimensional positional information of the trowels 31A, 31B relative to the object during formation of the object is the surface to be finished. In this case, the advancing and retreating movements of the trowels 31A, 31B are controlled based on the determination result. With this configuration, by utilizing the three-dimensional positional information of the trowels relative to the object during formation of the object, the advancing and retreating positions of the trowels 31A, 31B can be efficiently determined.

[0047] In this embodiment, the trowels 31A and 31B are positioned to the sides of a straight line L that passes through the central axis CL of the nozzle 13 and follows the direction of travel of the nozzle 13. In this configuration, the trowels 31A and 31B can be brought into appropriate contact with the surface of the cementitious material C from the sides to finish the surface.

[0048] In this embodiment, the finishing device 3 preferably includes a rotation mechanism 40 that rotates the trowels 31A and 31B relative to the nozzle 13 around the central axis CL of the nozzle 13. In this case, the operation of the rotation mechanism 40 is controlled so that the trowels 31A and 31B are positioned to the sides of lines L1 and L2 that pass through the central axis CL of the nozzle 13 and extend along the direction of travel of the nozzle 13. This configuration allows the trowels 31A and 31B to be rotated independently of the nozzle 13. This makes it possible to adjust the circumferential positions of the trowels 31A and 31B around the central axis CL of the nozzle 13, i.e., the orientation of the trowels 31A and 31B, by the rotation mechanism 40, without rotating the nozzle 13 itself.

[0049] This embodiment also includes a buffering device 53 and a control unit 54. The buffering device 53 temporarily stores pulse train data based on a code written in two-dimensional data for each layer obtained from the three-dimensional data of the shaped object. The control unit 54 analyzes the traveling direction of the nozzle 13 from the pulse train data stored in the buffering device 53. The control unit 54 also transmits a control signal to the rotation mechanism 40 based on the analyzed traveling direction of the nozzle 13 at the same timing as the pulse train data for moving the nozzle 13. With this configuration, temporarily storing the pulse train data in the buffering device 53 ensures time for analyzing the traveling direction of the nozzle 13. This allows the cementitious material C to be discharged from the nozzle 13 and the surface of the cementitious material C to be appropriately finished with the trowels 31A and 31B at the same time.

[0050] In this embodiment, the rotation mechanism 40 includes an outer stator 41, outer rotors 42A and 42B, and a servo motor 45. The outer stator 41 is fixed to the nozzle 13. The outer rotors 42A and 42B are disposed radially outside the outer stator 41 via bearings 48 so as to be rotatable together with the trowels 31A and 31B about the central axis CL of the nozzle 13. The servo motor 45 rotates the outer rotors 42A and 42B via a power transmission means. The power transmission means includes, for example, a first pulley 43 fixed to the outer rotor 42A and a second pulley 44 connected to the first pulley 43 via a belt 46 so as to transmit power. In this case, the servo motor 45 rotates the second pulley 44. This configuration enables the trowels 31A and 31B to be rotated reliably and quickly with a simple configuration.

[0051] In this embodiment, the finishing device 3 includes compression springs 32A and 32B and servo motors 33A and 33B. The compression springs 32A and 32B bias the irons 31A and 31B in their advancing directions. The servo motors 33A and 33B rewind the irons 31A and 31B in their retreating directions via thread-like members 34A and 34B. This simple configuration allows the irons 31A and 31B to be advanced and retreated reliably and quickly.

[0052] In this embodiment, the finishing portions 313A, 313B of the trowels 31A, 31B, which come into contact with the surface of the cementitious material C to form a finished surface, are positioned behind the center of the nozzle 13 in the direction of travel of the nozzle 13. With this configuration, the finishing portions 313A, 313B of the trowels 31A, 31B can be reliably brought into contact with the surface of the cementitious material C discharged from the nozzle 13 to finish the surface.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the invention. For example, the surface of the cementitious material C discharged from the nozzle 13 can be finished or not, independently of the inside and outside of a ring-shaped layer. For example, it is possible to finish only the outside of a cylindrical object and leave the inside unfinished, intentionally leaving unevenness. In this case, when concrete is poured into the interior of the cylindrical object, for example, it is possible to increase the adhesion between the two and integrate them. Furthermore, it is not only possible to use different finishes for the inside and outside of the surface, but also to finish only a portion of a single surface, thereby expanding the degree of freedom in design. Although a step is formed between the introduction portions 312A, 312B and the finishing portions 313A, 313B of the trowels 31A, 31B, this is not limitative and they may be on the same plane. In this case, the plane is preferably parallel to a line L that passes through the central axis CL of the nozzle 13 and follows the direction of travel of the nozzle 13, or is inclined so that the finishing portions 313A, 313B are closer to the line L than the introduction portions 312A, 312B. In the above embodiment, the trowels 31A and 31B are configured to advance in the direction of discharging the cement-based material and retreat in the direction opposite to the discharging direction. That is, in the above embodiment, the trowels 31A and 31B are configured to move linearly, but this is not limited to this. FIG. 15 is a schematic side view illustrating a trowel unit 30C according to a modified example. As shown in FIG. 15, the trowel unit 30C includes a servo motor 33A, a first link 302C, a second link 303C, and a trowel 31C. One end of the first link 302C is fixed to a shaft 301C rotated by the servo motor 33A, and the other end is rotatably connected to one end of the second link 303C. The other end of the second link 303C is rotatably connected to the tip end of the trowel 31C. The base end of the trowel 31C is rotatably connected to a hinge 304C. In other words, trowel 31C is configured so that by moving in the rotational direction, i.e., by rotating about hinge 304C, the tip of trowel 31C moves to a position advanced in the direction of discharging the cement-based material. In this case, when first link 302C is rotated in the direction indicated by arrow A, the tip of trowel 31C moves down, and when first link 302C is rotated in the direction indicated by arrow B, the tip of trowel 31C moves up. Trowel 31D can also be rotated by a mechanism (not shown) similar to that for rotating trowel 31C. The configuration of the nozzle support device 2 is not particularly limited as long as it is capable of moving the nozzle device 1 three-dimensionally, and for example, the nozzle device 1 may be attached to the tip of a multi-axis robot arm and supported. In this case, the rotation mechanism 40 may be omitted because the operation of the robot arm can rotate the irons 31A and 31B together with the nozzle 13. In the above embodiment, the three-dimensional modeling system 100 is described as moving the nozzle device 1 three-dimensionally, but the present invention is not limited to this. The three-dimensional modeling system 100 may be configured, for example, so that a three-dimensional model is formed by moving the nozzle device 1 in a plane and vertically moving a production table on which the model is formed. [Explanation of symbols]

[0054] 1 Nozzle device 13 nozzles 2 Nozzle support device 3 Finishing equipment 31A, 31B Iron 313A, 313B Finishing Section 32A, 32B Compression spring 33A, 33B Servo motor (motor) 34A, 34B Thread-like member 40 Rotation mechanism 41 outer stator 42A, 42B outer rotor 43 First pulley 44 Second pulley 45 Servo motor (motor) 46 Belt 48 Bearings 5. Control device 53 Buffering Device 54 Control Unit 65 Sculptures 100 3D Modeling System C. Cement-based materials CL center axis L,L1,L2 straight line θ Traveling direction

Claims

1. A three-dimensional modeling system for forming a three-dimensional object by stacking cement-based materials, a nozzle for discharging the cement-based material; a nozzle support device that movably supports the nozzle; a finishing device attached to the nozzle and configured to finish the surface of the cementitious material discharged from the nozzle, the finishing device has a trowel that is movable so that its tip is positioned at a position advanced in the direction of discharging the cement-based material, the finishing device has a rotation mechanism that rotates the trowel relative to the nozzle around a central axis of the nozzle, A three-dimensional modeling system, characterized in that the operation of the rotation mechanism unit is controlled so as to position the trowel to the side of a straight line that passes through a central axis of the nozzle and follows a direction in which the nozzle advances.

2. The three-dimensional modeling system according to claim 1 , wherein the trowel is capable of advancing in a direction in which the cement-based material is dispensed and retracting in a direction opposite to the direction in which the cement-based material is dispensed.

3. 3. The three-dimensional modeling system according to claim 1, wherein the system determines whether the surface of the cementitious material that comes into contact with the trowel when it is advanced is a surface to be finished, based on three-dimensional position information of the trowel relative to the object during the formation of the object, and controls the movement of the trowel based on the determination result.

4. 4. The three-dimensional object fabrication system according to claim 1, wherein the trowel is positioned to the side of a straight line that passes through a central axis of the nozzle and extends along a direction in which the nozzle advances.

5. a buffering device that temporarily stores pulse train data based on a code described in two-dimensional data for each layer obtained from the three-dimensional shape data of the object; a control unit that analyzes the direction of travel of the nozzle from the pulse train data stored in the buffering device, and transmits a control signal to the rotation mechanism unit based on the analyzed direction of travel of the nozzle at the same timing as the pulse train data for moving the nozzle.

6. The three-dimensional modeling system according to claim 1 or claim 5, characterized in that the rotation mechanism comprises an outer stator fixed to the nozzle, an outer rotor arranged radially outside the outer stator via a bearing so as to be rotatable together with the iron around the central axis of the nozzle, and a motor that rotates the outer rotor via a power transmission means.

7. The three-dimensional modeling system according to claim 6, characterized in that the power transmission means has a first pulley fixed to the outer rotor and a second pulley connected to the first pulley via a belt so that power can be transmitted, and the motor drives the second pulley to rotate.

8. The three-dimensional modeling system according to any one of claims 1 to 7, characterized in that the finishing device includes a compression spring that urges the trowel in the advancing direction of the trowel, and a motor that rewinds the trowel via a filament-like member in the retreating direction of the trowel.

9. 9. The three-dimensional modeling system according to claim 1, wherein a finishing portion of the trowel that contacts the surface of the cement-based material to form a finished surface is positioned rearward of the center of the nozzle in the direction of travel of the nozzle.

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