Three-dimensional molding method and method for manufacturing three-dimensional molded object

Abstract

To improve a mechanical property of a three-dimensional molded object molded by a so-called core-shell three-dimensional molding method.SOLUTION: A three-dimensional molding method includes: a shell molding step in which a shell 4 that defines an outer shape of a three-dimensional object is molded by hardening a part of a fluid shell material 2; a core material filling step in which a fluidized core material 6 containing fiber reinforcement 6a is filled into a core part 5, which is a portion surrounded by the molded shell 4; and a core material hardening step for hardening the core material 6 filled in the core part 5. The core material filling step includes a discharge step in which a nozzle 14 for discharging the core material 6 is kept inserted into the unhardened shell material 2 remaining in the core part 5, and the core material 6 is discharged from the nozzle 14 so as to orient the fiber reinforcement 6a in a certain direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional modeling method and a method for manufacturing a three-dimensional object, and more specifically to a three-dimensional modeling method and a method for manufacturing a three-dimensional object using 3D printing technology, the performance of which has been improving in recent years, or optical modeling technology, which has been in practical use since before that. [Background technology]

[0002] The term 3D printer is widely used as the name for manufacturing equipment that uses 3D printing technology. A 3D printer is a three-dimensional modeling device that uses a computer to calculate the cross-sectional shape of an object based on 3D CAD data, divides the object into thin, circular cross-sectional components, forms these cross-sectional components using various methods, and stacks them to form the desired object. 3D printing technology is often used internationally as a synonym for Additive Manufacturing Technology, and the Japanese translation of the term is additive manufacturing technology.

[0003] In recent years, the introduction of additive manufacturing technology into the mass production of actual products and the production of prototypes before mass production has been under consideration. As a result, three-dimensional objects created using additive manufacturing technology are now required to have not only precision in their external shape but also strength. To meet these demands, a technology has been proposed for creating three-dimensional objects using a composite 3D printer that uses a composite material containing a resin material and a reinforcing material such as carbon fiber as the modeling material.

[0004] For example, Patent Document 1 listed below discloses a three-dimensional modeling method in which a shell, which is the outer layer of a three-dimensional object to be modeled, is first modeled using a shell material, and then a core material containing a reinforcing material is filled into the core portion, which is the portion surrounded by the modeled shell, and after multiple modeling of the shell and filling of the core material into the core portion are all completed, the core material is hardened all at once (hereinafter this method is also referred to as the core-shell method).

[0005] 7(a) and (b) show a schematic configuration of a three-dimensional object forming apparatus used in the three-dimensional object forming method described in Patent Document 1. The three-dimensional modeling device 100 functions as a composite 3D printer and includes a modeling tank 111 for storing shell material 2, a laser optical system 120 for irradiating an ultraviolet laser 121 to harden the shell material 2, and a core material supply system 130 equipped with a nozzle 131 for ejecting core material 6.

[0006] In the three-dimensional modeling method described in Patent Document 1, as shown in Figure 7(a), a shell 4 of a predetermined shape is formed on a modeling table 112 provided in a modeling tank 111 by irradiating a part of a shell material 2 with an ultraviolet laser 121 from a laser optical system 120, thereby hardening the part of the shell material 2, thereby forming the shell 4. 7(b), a nozzle 131 is inserted into the unhardened shell material 2 remaining in the core portion 5, which is the portion surrounded by the shaped shell 4, and a core material 6 is ejected. Because the specific gravity of the core material 6 is higher than that of the shell material 2, the remaining shell material 2 is replaced by the ejected core material 6, and the core portion 5 is filled with the core material 6.

[0007] After repeatedly performing the above-described molding of the shells 4 and filling of the core material 6, the core material 6 filled in the shells 4 is cured all at once to form a three-dimensional object. In the three-dimensional modeling method described in Patent Document 1, a combination of the shell 4 formed as an outer shell layer and the hardened core material 6 inside the shell 4 is called a three-dimensional model. According to the three-dimensional modeling method described in Patent Document 1, since there is no lamination interface in the hardened portion of the core material 6, it is possible to manufacture a three-dimensional object that has no directional property in rigidity or strength. [Problem to be solved by the invention]

[0008] The shapes of actual products and pre-production prototypes produced using additive manufacturing technology vary, and depending on the shape and application, there has been a desire to further improve the mechanical properties of the entire three-dimensional object or specific parts of the three-dimensional object. However, in the three-dimensional modeling method described in Patent Document 1, the fiber reinforcing material 6a contained in the core material 6 filled in the core portion 5 is irregularly dispersed as shown in Figure 7(b), making it difficult to meet demands such as improving the mechanical properties of the three-dimensional object in a specific direction, and there is room for further improvement in terms of improving the mechanical properties of the three-dimensional object. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-136923 Summary of the Invention Means to solve the problem and their effects

[0010] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a three-dimensional modeling method and a method for manufacturing a three-dimensional model that can improve the mechanical properties of a three-dimensional model formed by a so-called core-shell three-dimensional modeling method.

[0011] In order to achieve the above object, the three-dimensional object fabrication method (1) according to the present invention comprises: a shell forming process in which a shell that defines the outer shape of the three-dimensional object is formed by hardening a part of a shell material in a fluid state; a core material filling step of filling a fluidized core material containing a fiber reinforcement material into a core portion, which is a portion surrounded by the shaped shell; and hardening the core material filled in the core portion, The core material filling step The method is characterized by including a discharge step of discharging the core material from a discharge part that discharges the core material while maintaining the state in which the discharge part is inserted into the unhardened shell material remaining in the core part, so as to orient the fiber reinforcement material in a certain direction.

[0012] According to the above-mentioned three-dimensional modeling method (1), in the ejection process, the core material is ejected from the ejection part so as to orient the fiber reinforcement material in a certain direction while maintaining the ejection part inserted into the unhardened shell material remaining in the core part. Therefore, the core material is filled into the core portion while replacing the uncured shell material with the fiber reinforcement oriented in a certain direction. Then, in the subsequent core material curing step, the core material can be cured with the fiber reinforcement oriented in a certain direction. Therefore, the mechanical properties of the three-dimensional object in the given direction, i.e., the orientation direction of the fiber reinforcement, particularly the bending properties such as bending strength and bending modulus, can be improved.

[0013] Furthermore, the present invention provides a three-dimensional object fabrication method (2) in the above three-dimensional object fabrication method (1), The discharge step The core material is discharged from the discharge part while moving the discharge part so that the orientation direction of the fiber reinforcement material is approximately parallel to the movement direction of the discharge part.

[0014] According to the above-mentioned three-dimensional modeling method (2), as with the above-mentioned three-dimensional modeling method (1), the mechanical properties, particularly the bending properties, of the three-dimensional model can be improved relative to the orientation direction of the fiber reinforcement material, and the orientation direction of the fiber reinforcement material can be easily adjusted to any direction by changing the movement direction of the discharge part.

[0015] The three-dimensional object fabrication method (3) according to the present invention is the three-dimensional object fabrication method (1) or (2), further comprising: The discharge step The core material is discharged from the discharge portion at a predetermined position of the core portion, This is characterized by a process in which the core material is ejected from the ejection part while the tip of the ejection part is kept not inserted into the ejected core material and the ejection part is moved from the predetermined position.

[0016] According to the three-dimensional object fabrication method (3), in the discharging step, the core material is not agitated in the discharging section, and the fiber reinforcement contained in the core material discharged from the discharging section can be precisely oriented in the direction of movement of the discharging section, thereby enhancing the effect of improving the mechanical properties, particularly the bending properties, of the three-dimensional object relative to the orientation direction of the fiber reinforcement.

[0017] The three-dimensional object fabrication method (4) according to the present invention is the three-dimensional object fabrication method (1) or (2), further comprising: In the discharging step, The moving speed of the discharge part and the discharge speed of the core material are controlled so that the orientation direction of the fiber reinforcement material is approximately parallel to the moving direction of the discharge part.

[0018] According to the three-dimensional object fabrication method (4), in the discharging step, the moving speed of the discharge unit and the discharging speed of the core material are controlled so that the orientation direction of the fiber reinforcement is approximately parallel to the moving direction of the discharge unit, so that the fiber reinforcement contained in the core material discharged from the discharge unit can be oriented with high precision in the moving direction of the discharge unit, thereby enhancing the effect of improving the mechanical properties, particularly the bending properties, of the three-dimensional object relative to the orientation direction of the fiber reinforcement.

[0019] Furthermore, the present invention provides a three-dimensional object fabrication method (5) in any one of the three-dimensional object fabrication methods (1) to (4), wherein: The ejection step is performed on a specific region of the core portion.

[0020] According to the above three-dimensional object fabrication method (5), the discharging step is performed on a specific region of the core, so that the fiber reinforcement can be oriented in a fixed direction only in the specific region of the three-dimensional object, thereby improving the mechanical properties, particularly the bending properties, of the three-dimensional object in the orientation direction of the fiber reinforcement in the specific region.

[0021] The method for manufacturing a three-dimensional object according to the present invention is characterized in that the three-dimensional object is manufactured by using any one of the above three-dimensional object manufacturing methods (1) to (5).

[0022] According to the method for manufacturing a three-dimensional object, when manufacturing the three-dimensional object, the effects obtained by any of the three-dimensional object manufacturing methods (1) to (5) can be achieved, and a three-dimensional object can be manufactured with improved mechanical properties of the entire three-dimensional object or a specific part of the three-dimensional object. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram illustrating a configuration example of a three-dimensional object fabrication apparatus used in a three-dimensional object fabrication method according to an embodiment of the present invention. [Figure 2] 1A to 1D are diagrams illustrating an example of a three-dimensional object fabrication method according to an embodiment, in which (a) is a diagram illustrating a shell fabrication step, and (b) to (d) are diagrams illustrating a core material filling step. [Figure 3] 1A and 1B are diagrams for explaining an example of a three-dimensional object forming method according to an embodiment, in which FIG. 1A is a diagram for explaining a shell forming step, and FIGS. 1B and 1C are diagrams for explaining a core material filling step. [Figure 4] FIG. 10 is a perspective view illustrating an example of a three-dimensional object forming method according to an embodiment, illustrating a core material filling step. [Figure 5] 10 is a graph showing evaluation results of bending strength of hardened core materials of three-dimensional objects fabricated by three-dimensional fabrication methods according to examples and comparative examples. [Figure 6] 10 is a graph showing evaluation results of the bending modulus of elasticity of hardened core materials of three-dimensional objects fabricated by three-dimensional fabrication methods according to examples and comparative examples. [Figure 7] 1A and 1B are diagrams for explaining a conventional three-dimensional modeling method, in which FIG. 1A shows a step of forming a shell, and FIG. 1B shows a step of filling a core material. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the three-dimensional object manufacturing method and the three-dimensional object manufacturing method according to the present invention will be described with reference to the drawings. Note that the three-dimensional object and the shapes of its shell and core parts shown in the drawings are depicted schematically so that the gist of the present invention can be easily understood, and the present invention is not limited to these forms.

[0025] Fig. 1 is a schematic diagram showing an example of the configuration of a 3D modeling apparatus used in a 3D modeling method according to an embodiment. Figs. 2 and 3 are diagrams for explaining an example of a 3D modeling method according to an embodiment. In the drawings, the three axes of a Cartesian coordinate system are designated as X, Y, and Z, the horizontal direction is designated as the X-axis direction and the Y-axis direction, and the direction perpendicular to the XY plane (vertical direction) is designated as the Z-axis direction.

[0026] The three-dimensional modeling apparatus 10 mainly comprises a modeling tank 11, a laser optical system 12, and a core material supply system 13. The three-dimensional modeling apparatus 10 uses a liquid vat polymerization method, which is one of additive manufacturing techniques, to form a shell 4, which is the outer layer of the three-dimensional object to be modeled, and functions as a composite 3D printer that uses a composite material containing fiber reinforcement material 6a in a thermosetting resin as the core material 6.

[0027] In the 3D modeling apparatus 10, a shell 4, which is the outer layer of a 3D object, is formed in a modeling tank 11, and a core material 6 is filled into a core portion 5, which is the portion surrounded by the formed shell 4. The shell 4 filled with the core material 6 is then removed from the modeling tank 11, and the core material 6 is cured all at once, thereby forming a 3D object. The operation of each part of the 3D modeling apparatus 10 may be controlled by a control unit (not shown). Such a control unit may be configured, for example, as a general-purpose computer device.

[0028] The molding tank 11 stores, as the shell material 2 in a fluid state, a liquid phase material such as a photocurable resin, and a photocurable resin adjustment system (not shown) can maintain and adjust the liquid surface position at a predetermined position. For the shell material 2, known UV-curable resins such as epoxy and acrylic photocurable resins can be used as the photocurable resin. A molding table 15 is also provided within the molding tank 11. The molding table 15 supports the shell 4 during molding, and can be moved (raised and lowered) and set to any position in the Z-axis direction in the drawing by a lifting mechanism (not shown).

[0029] The laser optical system 12 is a mechanism for curing the shell material 2 made of a photocurable resin to form the shell 4, and includes an ultraviolet laser light source 12a and a scanning optical system 12b. The ultraviolet laser light source 12a emits ultraviolet laser light 12c, which is an active energy ray. The scanning optical system 12b adjusts the angle at which the ultraviolet laser light 12c emitted from the ultraviolet laser light source 12a is reflected, and irradiates the ultraviolet laser light 12c over a predetermined range on the liquid surface of the shell material 2 (i.e., the XY plane) while scanning it.

[0030] The shell material 2 made of photocurable resin is cured to a predetermined depth from the liquid surface by irradiation with the ultraviolet laser light 12c. This curing depth can be adjusted to a certain extent by adjusting the output of the ultraviolet laser light source 12a, for example, in the range of about 0.1 mm to 0.4 mm.

[0031] Then, by repeatedly irradiating the liquid surface of the shell material 2 with ultraviolet laser light 12c and adjusting (lowering) the height of the modeling table 15, a shell 4 made of an ultraviolet-cured resin layer with a predetermined three-dimensional shape is formed. This shell 4 functions as an outer shell layer for filling with the core material 6, and the part surrounded by the inner surface of the shell 4 and having a bottom surface is called the core part 5.

[0032] The core material supply system 13 is a mechanism for supplying the core material 6 in a fluid state to the core section 5, and is equipped with a core material tank 13a that stores the core material 6 inside, a pump 13b, piping systems 13c and 13d, and a nozzle 14. In the core material supply system 13, by driving the pump 13b, the core material 6 is supplied from the core material tank 13a via the piping systems 13c and 13d to the nozzle 14, and the core material 6 is discharged from the tip of the nozzle 14. The nozzle 14 is an example of a discharge unit. The nozzle 14 is movable in the X, Y, and Z axes directions by a nozzle movement mechanism (not shown). The core material supply system 13 can, for example, linearly move the nozzle 14 in a fixed direction on the XY plane at a fixed speed to discharge a fixed amount of core material 6. For this reason, the piping system 13d is constructed with a flexible structure and material so as to follow the movement of the nozzle 14. The shape of the tip (discharge port) of the nozzle 14 is not particularly limited, and may be, for example, circular or flat with a wide width.

[0033] The core material 6 is made of a composite material in which fiber reinforcement 6a is uniformly dispersed in a thermosetting resin, which is a known liquid phase material such as an epoxy or acrylic resin. The fiber reinforcement 6a is, for example, a fibrous reinforcement containing carbon fiber. The fiber reinforcement 6a is, for example, a powdered short fiber obtained by pulverizing raw carbon fiber yarn, i.e., milled carbon fiber. The average fiber length of the milled carbon fiber is not particularly limited, but is, for example, about 20 μm to 1000 μm, preferably about 30 μm to 300 μm, and more preferably about 50 μm to 150 μm. The fiber reinforcement 6a is not limited to carbon fiber, but may be glass fiber or aramid fiber, or may contain one or more of these. The core material 6 has the property of not mixing with the shell material 2, and has a higher specific gravity than the shell material 2. The viscosity of the core material 6 is preferably at least twice as high as that of the shell material 2.

[0034] Next, an example of a three-dimensional modeling method and a method for manufacturing a three-dimensional model according to an embodiment will be described with reference to Figures 2 and 3. In the following embodiment, an example will be described in which the shell 4, which forms the outer layer of the three-dimensional model, is formed in two separate steps, and a core portion 5, which is the portion surrounded by the shell 4, is filled with a core material 6 to form the three-dimensional model. Note that, depending on the size of the three-dimensional model and the shape of the core portion 5, the shell 4 may be formed in one step without being divided, or conversely, two or more divisions may be required. Regardless of the number of divisions in forming the shell 4, essentially the same steps are repeated, and there is no essential difference in the modeling method.

[0035] [Shell molding process] First, as shown in FIG. 2(a), the laser optical system 12 irradiates the shell material 2 in the modeling tank 11 with ultraviolet laser light 12c, and the shell 4 is modeled on the modeling table 15 to a height h1. Specifically, the height of the molding table 15 is adjusted to a predetermined depth position relative to the liquid surface of the shell material 2, ultraviolet laser light 12c is emitted from the ultraviolet laser light source 12a, and the ultraviolet laser light 12c is scanned by the scanning optical system 12b while irradiating a predetermined range of the liquid surface of the shell material 2, curing the shell material 2 to a predetermined depth (corresponding to the curing depth) to form a cured resin layer.

[0036] The height of the molding table 15 is adjusted and the shell material 2 is cured by irradiation with ultraviolet laser light 12c, and this process is repeated to form a shell 4 having a predetermined height (height h1 in this case) from the liquid surface of the shell material 2. The shell 4 is shaped like a box with a bottom and a rectangular opening on the top surface. The thickness of the shell 4 is not particularly limited, but it is preferable to form it thin, for example, to about 3 mm or less, and preferably about 1 mm or less.

[0037] [Core material filling process] After forming the shell 4 with a height h1, the height of the forming table 15 is adjusted so that the upper end of the shell 4 is positioned below the liquid surface of the shell material 2, as shown in FIG. 2(b). Next, the nozzle 14 is moved into the forming tank 11 by a nozzle movement mechanism (not shown), and at least the tip (discharge port) of the nozzle 14 is inserted into the shell material 2 remaining in the core section 5. The tip of the nozzle 14 is then positioned at a predetermined position within the core section 5 (e.g., on one side wall in the X-axis direction). The core material supply system 13 is then driven to start discharging the core material 6 from the tip of the nozzle 14. While discharging a fixed amount of core material 6 from the nozzle 14, the nozzle movement mechanism moves the nozzle 14 at a predetermined speed in the X-axis direction of the XY plane (discharge process). At this time, the nozzle 14 is moved while maintaining a state in which the tip of the nozzle 14 is not inserted into the discharged core material 6. Also, at this time, since the specific gravity of the core material 6 is higher than that of the shell material 2, the core material 6 sinks toward the bottom of the shell 4, and the shell material 2 remaining in the core portion 5 overflows from the top of the shell 4, and the shell material 2 in the core portion 5 is replaced by the core material 6.

[0038] In this discharging step, the nozzle 14 for discharging the core material 6 is kept inserted into the uncured shell material 2 remaining in the core portion 5, and the core material 6 is discharged from the nozzle 14 so as to orient the fiber reinforcement 6a contained in the core material 6 in a certain direction (the X-axis direction in the example of FIG. 2(b)). More specifically, the core material 6 is discharged from the nozzle 14 while moving the nozzle 14 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the moving direction of the nozzle 14.

[0039] After the tip of the nozzle 14 reaches the other sidewall in the X-axis direction within the core section 5, the nozzle 14 is moved in the Y-axis direction of the XY plane by the nozzle movement mechanism, as shown in FIG. 2(c). The movement width of the nozzle 14 in the Y-axis direction is, for example, less than the discharge width of the core material 6. Then, the operation of discharging the core material 6 from the tip of the nozzle 14 is restarted, and the nozzle movement mechanism moves the nozzle 14 in the X-axis direction of the XY plane at a predetermined speed while discharging a fixed amount of core material 6 from the nozzle 14. By repeatedly performing the reciprocating discharge operation of the nozzle 14 in the XY plane, one layer of core material 6 is filled into the bottom of the core section 5 with the fiber reinforcement 6a oriented in a fixed direction (the X-axis direction), as shown in FIGS. 2(b) and 2(c).

[0040] After filling the bottom of the core portion 5 with the core material 6 for one layer, the nozzle 14 is moved in the Z-axis direction by the nozzle movement mechanism, as shown in FIG. 2(d). The movement of the nozzle 14 in the Z-axis direction is, for example, less than the height of one layer of the core material 6. Then, the operation of discharging the core material 6 from the tip of the nozzle 14 is restarted, and the nozzle movement mechanism moves the nozzle 14 at a predetermined speed in the X-axis direction of the XY plane while discharging a fixed amount of the core material 6 from the nozzle 14. That is, the core material 6 is discharged while moving the nozzle 14 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the movement direction of the nozzle 14. Then, by repeatedly performing the reciprocating discharge operation of the nozzle 14 in the XY plane in the same manner as above, the core portion 5 is filled with the core material 6 for two layers, with the fiber reinforcement 6a oriented in a fixed direction (the X-axis direction), as shown in FIG. 2(d).

[0041] 2(b) to 2(d) is a process in which the nozzle 14 is moved to discharge the core material 6 while maintaining a state in which the tip of the nozzle 14 is not inserted into the discharged core material 6. In addition, in the discharge process, the movement speed of the nozzle 14 and the discharge speed of the core material 6 are controlled so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the movement direction of the nozzle 14.

[0042] Next, we will explain the process of further molding a shell 4 of height h2 on top of the already molded shell 4 of height h1 so that the height of the shell 4 becomes H, and filling the newly molded core portion 5 with core material 6.

[0043] [Shell molding process] First, as shown in FIG. 3(a), the nozzle 14 is retracted from inside the core portion 5 to a predetermined position outside the shell 4 by the nozzle moving mechanism. Next, the height of the molding table 15 is adjusted so that the top surface of the shell 4 with height h1 is at a predetermined depth relative to the liquid surface of the shell material 2, and ultraviolet laser light 12c is emitted from the ultraviolet laser light source 12a of the laser optical system 12. Then, the ultraviolet laser light 12c is scanned by the scanning optical system 12b, irradiating a predetermined area of ​​the liquid surface of the shell material 2 on the top surface of the shell 4, and a new shell 4 is molded by being layered on top of the shell 4 with height h1. By repeating this operation, a new shell 4 with height h2 is molded by being layered on top of the previously molded shell 4 with height h1. Then, a shell 4 with height H is molded.

[0044] [Core material filling process] After forming the shell 4 with a height h2, as shown in FIG. 3(b), the height of the forming table 15 is adjusted so that the upper end of the shell 4 is positioned below the liquid surface of the shell material 2. Next, the nozzle movement mechanism is used to move the tip of the nozzle 14 into the core section 5, and the tip of the nozzle 14 is positioned at a predetermined position within the core section 5 (for example, on one side wall side in the X-axis direction). Thereafter, the core material supply system 13 is driven to start the operation of discharging the core material 6 from the tip of the nozzle 14. While discharging a fixed amount of the core material 6 from the nozzle 14, the nozzle movement mechanism moves the nozzle 14 at a predetermined speed in the X-axis direction of the XY plane. That is, the core material 6 is discharged from the nozzle 14 while moving the nozzle 14 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the movement direction of the nozzle 14.

[0045] 2(c), the nozzle 14 is moved in the Y-axis direction of the XY plane by the nozzle movement mechanism, and the operation of discharging the core material 6 from the tip of the nozzle 14 is restarted. The nozzle 14 is moved at a predetermined speed in the X-axis direction of the XY plane while discharging a fixed amount of the core material 6 from the nozzle 14. By repeatedly performing the reciprocating discharge operation of the nozzle 14 in the XY plane, one layer of the core material 6 is filled on top of the previously filled core material 6 with the fiber reinforcing material 6a oriented in a fixed direction (the X-axis direction), as shown in FIG.

[0046] 3(c), the nozzle 14 is moved in the Z-axis direction by the nozzle movement mechanism, and the operation of discharging the core material 6 from the tip of the nozzle 14 is then resumed. The nozzle 14 is moved at a predetermined speed in the X-axis direction of the XY plane while discharging a fixed amount of core material 6 from the nozzle 14. That is, the core material 6 is discharged while moving the nozzle 14 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the direction of movement of the nozzle 14. Then, by repeating the reciprocating discharge operation of the nozzle 14 in the XY plane in the same manner as above, two layers of core material 6 are filled into the core portion 5 of the shell 4 having a height h2, as shown in FIG. 3(c), with the fiber reinforcement 6a oriented in a fixed direction (the X-axis direction).

[0047] Since the core material 6 is an uncured liquid phase material with fluidity, even if additional core material 6 is filled up to a height h2 on top of the core material 6 that has already been filled up to a height h1, no interface (molding interface) will be formed on the surface at height h1 between the additional core material 6 and the already filled core material 6. The shell molding process and core material filling process are usually carried out in a room temperature environment (for example, 20°C to 30°C).

[0048] Then, once the core material filling process is completed, the forming table 15 in the forming tank 11 is raised above the liquid level of the shell material 2, and the shell 4 filled with the core material 6 is removed from the forming table 15, and the process proceeds to the next core material hardening process.

[0049] [Core material hardening process] In the core material hardening step, the shell 4 filled with the core material 6 is placed in a heat hardening means (not shown), such as a heating furnace having a chamber that can seal the heating target, to harden the core material 6 all at once. That is, the shell 4 filled with the core material 6 is placed in the heating furnace, and the temperature inside the heating furnace is raised to a temperature higher than the heat hardening temperature of the core material 6. This heats the shell 4 and the core material 6, causing the hardening of the core material 6 to proceed, and after a predetermined time has passed, the hardening of the entire core material 6 is completed, resulting in a three-dimensional object consisting of the shaped shell 4 and the hardened core material 6. In the three-dimensional object thus produced, the fiber reinforcing material 6 a in the hardened core material 6 is oriented in a fixed direction, that is, in a direction substantially parallel to the direction of movement of the nozzle 14 .

[0050] According to the three-dimensional object fabrication method of the above embodiment, in the core material filling step, the nozzle 14 is kept inserted into the uncured shell material 2 remaining in the core portion 5, and the core material 6 is discharged from the nozzle 14 so as to orient the fiber reinforcement material 6a in a fixed direction. More specifically, the nozzle 14 is moved so that the orientation direction of the fiber reinforcement material 6a is approximately parallel to the movement direction of the nozzle 14, and the core material 6 is discharged from the nozzle 14. Therefore, the core material 6 is filled into the core portion 5, replacing the uncured shell material 2, with the fiber reinforcement material 6a oriented in a fixed direction, i.e., approximately parallel to the movement direction of the nozzle 14.

[0051] Furthermore, in the core material filling process, the nozzle 14 is moved from a predetermined position while the tip of the nozzle 14 is kept out of the extruded core material 6, and the core material 6 is extruded from the nozzle 14. This prevents the core material 6 from being stirred by the nozzle 14, and also suppresses the phenomenon in which the fiber reinforcing material 6a disperses in all directions from the tip of the nozzle 14, allowing the fiber reinforcing material 6a contained in the core material 6 extruded from the nozzle 14 to be precisely oriented in the direction of movement of the nozzle 14. Furthermore, by controlling the movement speed of the nozzle 14 and the discharge speed of the core material 6 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the movement direction of the nozzle 14, the fiber reinforcement 6a contained in the core material 6 discharged from the nozzle 14 can be precisely oriented in the movement direction of the nozzle 14.

[0052] Then, in the subsequent core material hardening step, the core material 6 can be hardened in a state in which the fiber reinforcement 6a in the core portion 5 is oriented in a fixed direction. Therefore, the mechanical properties of the three-dimensional object in the orientation direction of the fiber reinforcing material 6a contained in the hardened core material 6, particularly bending properties such as bending strength and bending elasticity, can be improved.

[0053] In the above embodiment, the shell material 2 used to form the shell 4 is described as a liquid phase material, but the method of forming the shell 4 is not limited to the method of hardening a liquid phase material (liquid phase polymerization method), and other additive manufacturing methods such as fused deposition modeling may also be applied.

[0054] Furthermore, according to the above embodiment, a method of scanning the ultraviolet laser light 12c by the scanning optical system 12b is adopted, but in another embodiment, a method of exposing the cross-sectional shape all at once may be adopted. Furthermore, the core material 6 may be any material that can be cured in one go after being filled into the core part 5, and may be made of a photocurable resin in addition to a thermosetting resin. In this case, after filling the core material 6, the entire core part 5 can be irradiated with active energy rays to cure the core material 6, thereby obtaining a three-dimensional object. Furthermore, in the above embodiment, the three-dimensional object is a combination of the shell 4 formed as the outer shell layer and the hardened core material 6 inside the shell 4, but in another embodiment, after forming, the shell 4 as the outer shell layer may be removed, and the portion consisting of the hardened core material 6 may be used as the three-dimensional object.

[0055] 4 is a perspective view illustrating a core material filling step in a three-dimensional object fabrication method according to another embodiment of the present invention, in which the fabrication tank 11 and the shell material 2 are omitted for simplicity. The shell 4A formed in the shell forming process has an approximately T-shaped shape in a plan view, and has a first shell portion 4a that is long in the X-axis direction and a second shell portion 4b that is long in the Y-axis direction, with the height of the second shell portion 4b being half the height of the first shell portion 4a.

[0056] In the process of filling the core portion 5 of the first shell portion 4a with the core material 6, the nozzle 14 is moved in the X-axis direction at a predetermined speed while a fixed amount of the core material 6 is discharged from the nozzle 14 so as to orient the fiber reinforcement 6a in the core material 6 in the X-axis direction. In addition, in the process of filling the core portion 5 of the second shell portion 4b with the core material 6, the nozzle 14 is moved in the Y-axis direction at a predetermined speed while a fixed amount of the core material 6 is discharged from the nozzle 14 so as to orient the fiber reinforcement 6a in the core material 6 in the Y-axis direction. In this way, the orientation direction of the fiber reinforcement 6a can be controlled to any direction by changing the direction of movement of the nozzle 14 according to the shape of each part of the shell 4A.

[0057] In another embodiment, the first shell portion 4a may be filled with the fiber reinforcement 6a in a dispersed state without being oriented in a predetermined direction, and a fixed amount of the core material 6 may be discharged from the nozzle 14 while moving the nozzle 14 in the Y-axis direction at a predetermined speed so that the fiber reinforcement 6a in the core material 6 is oriented in the Y-axis direction only for the second shell portion 4b. Furthermore, in another embodiment, the core material 6 may be ejected while moving the nozzle 14 so that the orientation direction of the fiber reinforcement 6a is approximately parallel to the moving direction of the nozzle 14 only onto the upper part of the core portion 5, which is the portion surrounded by the first shell portion 4a and the second shell portion 4b. The above-described ejection step of orienting the fiber reinforcement 6a in a predetermined direction may be performed on a specific region of the core portion 5, particularly on a portion where it is desired to increase the mechanical strength. [Example]

[0058] Examples and comparative examples will be described below. [Example 1] A three-dimensional object was fabricated using the three-dimensional fabrication method according to the embodiment described above, and the portion of this three-dimensional object from which the shell 4 was removed, that is, the portion of the hardened core material 6, was used as a sample for evaluating mechanical properties. In the three-dimensional modeling method according to Example 1, a three-dimensional object was fabricated so that the dimensions of the hardened core material 6 were approximately 12 mm in width × 82 mm in length × 6 mm in thickness. In the core material filling step of the three-dimensional modeling method according to Example 1, the core material 6 was discharged while moving the nozzle 14 in the lengthwise direction so as to orient the fiber reinforcement material 6a in the lengthwise direction of the above dimensions. The shell material 2 used to form the shell 4 was an epoxy-based ultraviolet curing resin. The core material 6 was an epoxy-based thermosetting resin containing fiber reinforcement 6a. The fiber reinforcement 6a was milled (short fiber) carbon fiber with an average fiber length of approximately 100 to 150 μm. The viscosity of the core material 6 was approximately 1000 to 2000 mPa·s.

[0059] [Comparative Example 1] The three-dimensional object fabrication method according to Comparative Example 1 differs from the three-dimensional object fabrication method according to Example 1 only in the core material filling step. That is, in the core material filling process of the three-dimensional modeling method according to Comparative Example 1, the conventional method shown in FIG. 7(b) was used, i.e., a nozzle 131 was inserted into the unhardened shell material 2 remaining in the core portion 5, and the core material 6 was ejected, filling the core material 6 so that the fiber reinforcement material 6a was dispersed in irregular directions. Other molding conditions were basically the same as those in Example 1. That is, the same materials as those in Example 1 were used for the shell material 2, core material 6, etc., and the dimensions of the hardened core material 6 portion were also molded to be approximately the same as those in Example 1.

[0060] As evaluation indices for the mechanical properties of the hardened core material 6 fabricated by the three-dimensional fabrication methods according to Example 1 and Comparative Example 1, the bending strength and bending modulus were calculated. Six faces of the shaped sample of the hardened core material 6 were polished to prepare a test piece having a width of 10 mm, a length of 80 mm and a thickness of t4 mm. These test pieces were subjected to a three-point bending test in accordance with JIS K6911 (general testing method for thermosetting plastics). The bending test was carried out using a Shimadzu Corporation product name "Autograph AG-X" testing machine.

[0061] FIG. 5 shows the evaluation results of the bending strength of the hardened core materials 6 fabricated by the three-dimensional fabrication methods according to Example 1 and Comparative Example 1, and FIG. 6 shows the evaluation results of the bending modulus of elasticity. According to the evaluation results of bending strength shown in FIG. 5, the bending strength value of Example 1 (average value: 160 MPa) was about 1.5 times higher than the bending strength value of Comparative Example 1 (average value: 107 MPa). Furthermore, according to the evaluation results of the flexural modulus shown in FIG. 6, the flexural modulus value of Example 1 (average value 10 GPa) was approximately twice as high as the flexural modulus value of Comparative Example 1 (average value: 4.7 GPa).

[0062] In addition, an X-ray CT device (manufactured by Baker Hughes, device name: Phoenix v|tome|x m300 Nanofocus) was used to observe the orientation state of the fiber reinforcement material 6a contained in the hardened core material 6 formed using the three-dimensional forming method of Example 1 and Comparative Example 1. As a result, it was observed that the fiber reinforcement 6a was oriented in one axis direction, i.e., in the length direction of the test piece, in the evaluation sample of Example 1. On the other hand, in the evaluation sample of Comparative Example 1, it was not observed that the fiber reinforcement 6a was oriented in a specific direction.

[0063] The evaluation results of Example 1 and Comparative Example 1 confirmed that the 3D modeling method according to this embodiment can harden the core material 6 while orienting the fiber reinforcement 6a in a specific direction. Furthermore, it was confirmed that the mechanical properties of the 3D model, particularly bending properties such as bending strength and bending modulus, can be improved in relation to the orientation direction of the fiber reinforcement 6a.

[0064] The present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these modifications are also included within the scope of the present invention. The present invention is widely applicable in the field of additive manufacturing technology, such as 3D printers. By applying the present invention to such fields, it becomes possible to realize not only prototyping but also mass production of parts and products that require light weight and high strength, such as parts used in various industrial equipment such as automobiles, aircraft, and robots, as well as nursing care products and sporting goods. [Explanation of symbols]

[0065] 2. Shell material 4, 4A shell 4a First shell part 4b Second shell part 5 Core 6 Core material 6a Fiber reinforcement 10 Three-dimensional modeling device 11 Modeling tank 12 Laser optics 12a Ultraviolet laser 12b Scanning optical system 12c Ultraviolet laser light 13 Core material supply system 13a Core material tank 13b Pump 13c, 13d Piping system 14 Nozzle (discharge part) 15 Modeling stand 100 Three-dimensional modeling equipment 111 Modeling tank 112 Modeling stand 120 Laser Optics 121 Ultraviolet Laser 130 Core material supply system 131 nozzle

Claims

1. a shell forming process in which a shell that defines the outer shape of the three-dimensional object is formed by hardening a part of a shell material in a fluid state; a core material filling step of filling a fluidized core material containing a fiber reinforcement material into a core portion, which is a portion surrounded by the shaped shell; and hardening the core material filled in the core portion, The core material filling step A three-dimensional modeling method comprising: a discharging step of discharging the core material from a discharge part while maintaining the core material inserted into the unhardened shell material remaining in the core part, so as to orient the fiber reinforcement material in a certain direction.

2. The discharge step 2. The three-dimensional object fabrication method according to claim 1, further comprising the step of discharging the core material from the discharge unit while moving the discharge unit so that the orientation direction of the fiber reinforcement material is approximately parallel to the movement direction of the discharge unit.

3. The discharge step The core material is discharged from the discharge portion at a predetermined position of the core portion, The three-dimensional fabrication method according to claim 1, characterized in that the core material is ejected from the ejection part while the tip of the ejection part is kept not inserted into the ejected core material and the ejection part is moved from the predetermined position.

4. In the discharging step, 2. The three-dimensional object fabrication method according to claim 1, wherein the moving speed of the discharge part and the discharging speed of the core material are controlled so that the orientation direction of the fiber reinforcement material is approximately parallel to the moving direction of the discharge part.

5. 2. The three-dimensional object fabrication method according to claim 1, wherein the discharging step is performed on a specific region of the core portion.

6. A method for manufacturing a three-dimensional object, comprising manufacturing the three-dimensional object by using the three-dimensional object manufacturing method according to any one of claims 1 to 5.

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