Method for reinforcing three-dimensional object, and method for manufacturing three-dimensional object

Abstract

To provide a method for reinforcing a three-dimensional object, which can improve mechanical properties in a lamination direction of a three-dimensional object molded by additive manufacturing technology.SOLUTION: A method for reinforcing a three-dimensional object 10 molded using additive manufacturing technology includes a step of molding a reinforcing part 11 that covers at least a part of a laminated side surface 10b on a surface of the three-dimensional object 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for reinforcing a three-dimensional object and a method for manufacturing a three-dimensional object, and more particularly to a method for reinforcing a three-dimensional object formed using additive manufacturing techniques such as 3D printing, and a method for manufacturing a three-dimensional object. [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] ASTM International, an international standardization organization, broadly classifies additive manufacturing methods into the following seven categories: (1) Liquid bath polymerization method (Vat Photopolymerization) (2) Material extrusion (3) Powder bed fusion (4) Binder Jetting (5) Sheet lamination (6) Material Jetting (7) Directed Energy Deposition An overview of these molding methods is also described in, for example, Non-Patent Document 1 below.

[0004] (1) Among these, liquid tank polymerization was the earliest to be put to practical use, and it was used for rapid prototyping under names such as photopolymerization and SLA (stereolithography) before the term 3D printer became common.

[0005] FIG. 4 is a diagram showing an example of the configuration of a three-dimensional modeling apparatus using the liquid vat polymerization method. In the liquid vat polymerization method, for example, an ultraviolet-curable (polymerizable) resin 48 is held in a vat 46, and ultraviolet light 42 is selectively irradiated onto the liquid surface from an introduction optical system 40 to form a first-layer cured region 48a (FIGS. 4(a) to 4(c)). The first-layer cured region 48a is supported on a modeling table 47. Note that a suitable support material is formed between the first-layer cured region 48a and the modeling table 47. The introduction optical system 40 also includes an ultraviolet source 41, a collimating lens 43, a condenser lens 44, and a reflecting mirror 45.

[0006] Next, the first layer cured area 48a is submerged in the liquid together with the modeling table 47 (FIG. 4(d)), or the liquid level is raised to submerge the first layer cured area 48a to a certain depth. Next, ultraviolet light 42 is selectively irradiated to the liquid surface again, and a second layer cured area 48b is formed above the first layer cured area 48a so that it is continuous with the first layer cured area 48a in the stacking direction (FIG. 4(e)). This process is repeated to form a three-dimensional object.

[0007] Many of the 3D printers available for personal use in recent years use either the (2) material extrusion method or the (6) material jetting method. (2) The material extrusion method, also known as fused deposition modeling (FDM), is a method in which a modeling material, often made of thermoplastic resin, is heated to a molten, fluid state, and then extruded from a nozzle to form a layer.

[0008] FIG. 5 is a diagram showing an example of the configuration of a three-dimensional modeling apparatus using the material extrusion method. The chamber 50 is filled with pellets 51 made of, for example, granular thermoplastic resin. Then, the chamber 50 is heated by a heating mechanism (not shown), and the pellets 51 melt. The pellets 51 that have melted and become fluid are referred to as molten material 52 here. The molten material 52 is extruded from a nozzle 54 by a pressure force P applied by a pressure member 53. The extruded molten material 52 is placed on a modeling table 55. The modeling table 55 has, for example, a translational degree of freedom in the in-plane direction of the modeling table 55 indicated by arrows X and Y in the figure, a degree of freedom in the up-down direction of the modeling table 55 indicated by arrow Z, and a degree of freedom of rotation about a support shaft 56 (arrow θ in the figure).

[0009] As the molten material 52 is extruded from the nozzle 54, the modeling table 55 is driven in the directions of the arrows X, Y, and θ, and the molten material 52 is placed in any planar shape on the surface of the modeling table 55. The first layer of molten material placed on the surface of the modeling table 55 corresponds to the first layer 57 as a cross-sectional component. After molding of the first layer 57 is completed, the modeling table 55 is lowered, and a second layer is stacked on top of the first layer 57. By repeating this process, a three-dimensional object is formed.

[0010] (6) Material jetting is also known as inkjet material jetting or MJP (Multijet Printing), and the viscosity of the modeling material is often slightly lower than that of (2) material extrusion. In other words, instead of using ink in an inkjet printer, the modeling material is ejected and layered to create a shape.

[0011] (3) Powder bed fusion and (4) binder jetting are characterized by the use of powder or granular materials as the molding material. (3) Powder bed fusion bonding is also known as powder sintering, SLS (Selective Laser Sintering), SLM (Selective Laser Melting), etc. FIG. 6 is a diagram showing an example of the configuration of a three-dimensional fabrication apparatus using powder bed fusion. As shown in Figure 6, a powdered modeling material 61 is placed in a suitable tank 60. This is often referred to as a material bed 62. One of the features of this method is that a wide range of modeling materials can be selected, including inorganic materials such as metals, resins, and ceramics, as long as they are meltable with energy rays. Then, as shown in Figure 6(a), a laser beam 66 is selectively irradiated onto the surface of the material bed 62, melting and merging the powdered modeling material 61 to form a first modeling layer 67. In Figure 6, an infrared laser 63 is used as the energy beam source, and galvanometer optical systems 64 and 65 are used to arbitrarily scan the surface of the material bed 62. Next, as shown in Figure 6(b), after a certain amount of powdered modeling material 61 is added, the table 69 is lowered a certain distance, and the squeegee 68 is moved in the direction of arrow A in the figure to evenly and flatten the powdered modeling material 61. This again forms the material bed 62. Next, the laser beam 66 is scanned to form a second modeling layer. By repeating this process, a three-dimensional object is formed.

[0012] (4) The binder jetting method is also called inkjet binder jetting or CJP (Color Jet Printing). Similar to the powder bed fusion method (3), a material bed consisting of modeling material powder is used, and a binder material that functions as an adhesive to bind the modeling material powder to the material bed is selectively sprayed from an inkjet head or the like, thereby binding the modeling material powder together to form a shape.

[0013] (5) As the name suggests, the sheet lamination method is a method of forming a three-dimensional object by cutting sheet materials such as paper or plastic film into a laminated cross-sectional shape, and then stacking and adhering them in sequence.

[0014] (7) Directed energy deposition is also known as laser deposition or LMD (Laser Metal Deposition). FIG. 7 is a diagram showing an example of the configuration of a three-dimensional modeling apparatus using directed energy deposition. Directed energy deposition is a method of stacking a modeling material while simultaneously supplying the modeling material and selectively applying energy, as shown in Figure 7. A laser beam 71 passes through the inner nozzle 73 of the double-tube nozzle 72 and is focused onto the surface of a base 75 by a focusing lens 74. From the outer nozzle 76, a build material powder 78 (indicated by the arrow in the figure) is sprayed toward the focal point of the laser beam 71 along with shielding gas. At the focal point of the laser beam 71, the sprayed build material powder 78 is heated and melted by the laser beam 71, forming a molten pool 77 on the surface of the base 75, where the build material powder 78 melts and condenses. The relative positions of the base 75 and the double-tube nozzle 72 are then moved, and the build material is placed and layered on the base 75 while the molten pool 77 floats on the base 75. This method is a typical example of a 3D printer using metallic materials. From another perspective, this method can also be seen as a refined and automated development of the long-known arc welding method.

[0015] [Problem to be solved by the invention] All of the additive manufacturing methods (1) to (7) described above involve dividing an object into thin, cross-sectional slices and then stacking these cross-sectional slices to form the desired object. Because these methods are essentially additive manufacturing, the physical properties of the object, such as mechanical properties (tensile, bending, impact, and hardness), generally vary depending on the manufacturing direction, i.e., they are anisotropic, although the degree of variation varies depending on the method. Therefore, regardless of the method used, there is a problem in that the mechanical properties of the object tend to decrease in the stacking direction. This has made it difficult to apply additive manufacturing to the production of finished products or prototypes that are subject to loads. [Prior art documents] [Non-patent literature]

[0016] [Non-Patent Document 1] FY2019 Patent Application Technology Trends Survey Results Summary 3D Printers February 2020 Japan Patent Office Summary of the Invention Means to solve the problem and their effects

[0017] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a method for reinforcing a three-dimensional object and a method for manufacturing a three-dimensional object that can improve the mechanical properties in the stacking direction of a three-dimensional object created by additive manufacturing technology.

[0018] In order to achieve the above object, the present invention provides a method (1) for reinforcing a three-dimensional object, which comprises: A method for reinforcing a three-dimensional object formed using additive manufacturing technology, comprising: The method is characterized by including a step of forming a reinforcing portion that covers at least a part of the laminated side surface of the surface of the three-dimensional object.

[0019] According to the above-described method (1) for reinforcing a three-dimensional object, the reinforcing portion is formed so as to cover at least a portion of the stacked side surface of the three-dimensional object, thereby improving the mechanical properties of the three-dimensional object at least in the stacking direction.

[0020] A method (2) for reinforcing a three-dimensional object according to the present invention is the method (1) for reinforcing a three-dimensional object, wherein the reinforcing portion is made of a resin containing a reinforcing material.

[0021] According to the above-mentioned method (2) for reinforcing a three-dimensional object, the reinforcing portion is made of the reinforcing material-containing resin, and therefore the mechanical properties of the reinforcing material contained in the reinforcing material-containing resin can improve the mechanical properties of the three-dimensional object at least in the stacking direction.

[0022] A method (3) for reinforcing a three-dimensional object according to the present invention is the method (2) for reinforcing a three-dimensional object, characterized in that the reinforcing material-containing resin is a carbon fiber-containing thermosetting resin.

[0023] According to the method (3) for reinforcing a three-dimensional object, the reinforcing material-containing resin is a carbon fiber-containing thermosetting resin, and the excellent mechanical properties of the carbon fibers contained in the carbon fiber-containing thermosetting resin can further improve the mechanical properties of the three-dimensional object at least in the stacking direction.

[0024] The method for reinforcing a three-dimensional object (4) according to the present invention is the method for reinforcing a three-dimensional object (3) described above, characterized in that the carbon fiber-containing thermosetting resin contains milled carbon fibers.

[0025] According to the above-mentioned three-dimensional object reinforcement method (4), since the carbon fiber-containing thermosetting resin contains milled carbon fibers, in addition to the effects described in the above-mentioned reinforcement method (3), processing of the reinforcement portion, for example, cutting processing such as drilling holes and chamfering, can be easily performed, thereby improving the mechanical properties of the three-dimensional object as well as its processability.

[0026] The method (1) for producing a three-dimensional object according to the present invention includes the steps of: A process of forming a three-dimensional object using additive manufacturing technology; and forming a reinforcing portion that covers at least a part of the layered side surface of the surface of the three-dimensional object that has been formed.

[0027] According to the method (1) for manufacturing a three-dimensional object, the reinforcing portion can be easily formed so as to cover at least a part of the stacking side surface of the three-dimensional object, and therefore, the three-dimensional object can be easily manufactured with improved mechanical properties at least in the stacking direction due to the reinforcing portion.

[0028] Furthermore, the method for manufacturing a three-dimensional object (2) according to the present invention is characterized in that, in the method for manufacturing a three-dimensional object (1) described above, it further includes a step of processing the reinforcing portion after the step of molding the reinforcing portion.

[0029] According to the above-mentioned method (2) for manufacturing a three-dimensional object, since the method further includes a step of processing the reinforcing parts after the step of forming the reinforcing parts, the three-dimensional object can be manufactured while being reinforced by the reinforcing parts, and the three-dimensional object can be manufactured with the processed reinforcing parts. Therefore, the method can be applied to the manufacture of finished products with various shapes and prototypes that are subject to loads.

[0030] The method (3) for producing a three-dimensional object according to the present invention is the method (1) or (2) for producing a three-dimensional object, characterized in that the reinforcing portion is made of a resin containing a reinforcing material.

[0031] According to the method (3) for producing a three-dimensional object, the reinforcing portion is made of the reinforcing material-containing resin, and therefore, due to the mechanical properties of the reinforcing material contained in the reinforcing material-containing resin, it is possible to produce the three-dimensional object having improved mechanical properties at least in the stacking direction.

[0032] The method (4) for producing a three-dimensional object according to the present invention is the method (3) for producing a three-dimensional object, characterized in that the reinforcing material-containing resin is a carbon fiber-containing thermosetting resin.

[0033] According to the method (4) for producing a three-dimensional object, the reinforcing material-containing resin is a carbon fiber-containing thermosetting resin, and therefore, due to the excellent mechanical properties of the carbon fibers contained in the carbon fiber-containing thermosetting resin, it is possible to produce a three-dimensional object having further improved mechanical properties at least in the stacking direction.

[0034] The method (5) for producing a three-dimensional object according to the present invention is characterized in that, in the method (4) for producing a three-dimensional object, the carbon fiber-containing thermosetting resin contains milled carbon fiber.

[0035] According to the manufacturing method (5) of the three-dimensional object, the carbon fiber-containing thermosetting resin contains milled carbon fibers. This makes it possible to easily process the reinforcing parts, for example, by drilling holes or chamfering, in addition to the effects described in the manufacturing method (4), and thus makes it possible to manufacture the three-dimensional object with improved processability as well as improved mechanical properties in the stacking direction. [Brief explanation of the drawings]

[0036] [Figure 1] 1A and 1B are diagrams for explaining a method for reinforcing a three-dimensional object according to an embodiment of the present invention, in which FIG. 1A is a perspective view schematically showing a three-dimensional object formed using additive manufacturing technology, and FIG. 1B is a perspective view schematically showing a three-dimensional object having a reinforcement portion formed therein. [Figure 2] 10(a) to 10(f) are schematic views illustrating an example of a reinforcing portion molding step. [Figure 3] 10(a) to 10(e) are schematic views for explaining another example of a reinforcing portion molding step. [Figure 4] FIG. 1 is a schematic diagram illustrating an example of the configuration of a three-dimensional modeling apparatus using a liquid vat polymerization method. [Figure 5] FIG. 1 is a schematic diagram illustrating an example of the configuration of a three-dimensional object fabrication apparatus using a material extrusion method. [Figure 6] FIG. 1 is a schematic diagram showing an example of the configuration of a three-dimensional fabrication apparatus using powder bed fusion. [Figure 7] FIG. 1 is a diagram illustrating the principle of directed energy deposition. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments of the method for reinforcing a three-dimensional object and the method for manufacturing a three-dimensional object according to the present invention will be described with reference to the drawings. Note that the shapes of the three-dimensional object shown in the drawings are depicted schematically to facilitate understanding of the gist of the present invention, and the present invention is not limited to these shapes.

[0038] FIG. 1 is a diagram illustrating a method for reinforcing a three-dimensional object according to an embodiment, in which (a) is a perspective view schematically illustrating a three-dimensional object formed using additive manufacturing technology, and (b) is a perspective view schematically illustrating a three-dimensional object having a reinforcement portion formed therein.

[0039] The method for reinforcing a three-dimensional object according to the embodiment includes a step of forming a reinforcing portion 11 that covers at least a portion of the layered side surface 10b on the surface of a three-dimensional object 10 formed using additive manufacturing technology (reinforcing portion forming step).

[0040] In addition, the manufacturing method of a three-dimensional object according to the embodiment includes a process of forming a three-dimensional object 10 using additive manufacturing technology (forming process), and a process of forming a reinforcing portion 11 that covers at least a portion of the layered side surface 10b on the surface of the formed three-dimensional object 10 (reinforcing portion forming process).

[0041] The three-dimensional object 10 after the modeling process shown in FIG. 1(a) is additively manufactured using additive manufacturing technology as a three-way joint with an inverted T-shape in front view. The three-dimensional object 10 has a layer interface 10a and a layer side surface 10b of the cross-sectional components, and has an inverted T-shaped hole 10c with a circular cross section inside. Note that the surface of the three-dimensional object 10 includes not only its outer surface but also the inner surfaces of the hole 10c, etc., if the three-dimensional object 10 has such holes inside. Therefore, the layer side surface 10b includes not only the layer side surface 10ba on the outer surface of the three-dimensional object 10, but also the layer side surface 10bb on the inner surface of the hole 10c, etc.

[0042] After the reinforcing portion molding process illustrated in Figure 1(b), the three-dimensional object 10A has a reinforcing portion 11 molded as a reinforcing layer that covers the outer surface including the laminated side surface 10ba of the three-dimensional object 10 and the laminated side surface 10bb of the inner surface of the hole portion 10c, and a hole portion 11c covered with the reinforcing portion 11 is formed on the inner surface of the hole portion 10c of the three-dimensional object 10 by post-processing.

[0043] (modeling process) The additive manufacturing technology used in the modeling process is not particularly limited, and may be any of the additive manufacturing technology methods (1) to (7) described in the [Background Art] section. It is possible to model the three-dimensional object 10 using a known 3D printer device corresponding to each of these methods. However, a modeling material and an additive manufacturing technology method that minimize deformation or other morphological changes in the three-dimensional object 10 under the molding conditions in the reinforcement part molding process after the modeling process are appropriately selected.

[0044] To create highly rigid objects, it is preferable to use material extrusion or powder bed fusion methods, including Fuse Deposition Modeling (FDM), Arburg Plastic Freeforming (APF), and Continuous Filament Fabrication (CFF).

[0045] When using a material extrusion 3D printer to create a three-dimensional object, known thermoplastic resins can be used as the modeling material. Alternatively, thermoplastic resins containing various reinforcing materials such as carbon fiber can also be used as the modeling material. Examples of thermoplastic resins that can be used include general-purpose plastics such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylate-styrene-acrylonitrile (ABS); engineering plastics such as polyamide (PA), polyacetal (POM), polyethylene terephthalate (PET), and polycarbonate (PC); and super-engineering plastics such as aromatic polyamide (PPA), polyphenylene sulfide (PPS), polyetherimide (PEI), and polyether ether ketone (PEEK).

[0046] After the three-dimensional object 10 is formed using a 3D printer, unnecessary support portions (not shown) attached to the three-dimensional object 10 are cut off and removed. After removing these support portions, the surface of the three-dimensional object 10 may be polished, if necessary.

[0047] (Reinforcement part forming process) The reinforcing portion 11 formed in the reinforcing portion forming step is preferably made of a resin such as a reinforcing material-containing resin. The reinforcing material contained in the reinforcing material-containing resin may be, for example, at least one of fibrous reinforcing materials, granular reinforcing materials, and plate-shaped reinforcing materials, or two or more of these may be used in combination. Examples of fibrous reinforcing materials that can be used include carbon fibers, glass fibers, aramid fibers, and metal fibers. Examples of granular reinforcing materials that can be used include inorganic oxide particles such as silica and titanium oxide, salt particles such as carbonates such as calcium carbonate, sulfates, and phosphates, and metal particles. Examples of plate-like reinforcing materials that can be used include talc, mica, and glass flakes.

[0048] The resin constituting the reinforcing material-containing resin may be, for example, a thermosetting resin or a thermoplastic resin. The thermosetting resin may be, for example, an epoxy resin, a phenolic resin, an unsaturated polyester resin, or a melamine resin. Examples of thermoplastic resins that can be used include general-purpose plastics such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylate-styrene-acrylonitrile (ABS); engineering plastics such as polyamide (PA), polyacetal (POM), polyethylene terephthalate (PET), and polycarbonate (PC); and super-engineering plastics such as aromatic polyamide (PPA), polyphenylene sulfide (PPS), polyetherimide (PEI), and polyether ether ketone (PEEK).

[0049] As a preferred embodiment, a case will be described below in which the reinforcement-containing resin is made of a carbon fiber-containing thermosetting resin, and the carbon fiber-containing thermosetting resin contains milled carbon fibers. The thermosetting resin that constitutes the carbon fiber-containing thermosetting resin may be, for example, an epoxy resin, a phenolic resin, an unsaturated polyester resin, a melamine resin, a bismaleimide resin, or a cyanate resin.

[0050] The milled carbon fibers contained in the carbon fiber-containing thermosetting resin are powdered short fibers obtained by pulverizing raw carbon fiber yarns. The average fiber length of the short fibers 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 content of milled carbon fiber in the carbon fiber-containing thermosetting resin is not particularly limited, but is, for example, about 1% to 20% by volume, and preferably about 10% to 15% by volume. The viscosity of the carbon fiber-containing thermosetting resin at room temperature before curing is not particularly limited, but is, for example, about 1,000 to 10,000 (mPa·s), preferably about 1,000 to 5,000 (mPa·s), and more preferably about 1,000 to 2,000 (mPa·s). The carbon fiber-containing thermosetting resin may also contain other additives such as a curing agent.

[0051] FIG. 2 is a schematic diagram illustrating an example of the reinforcing portion molding step. 2 shows a molding process using a molding die 20. The molding die 20 is configured to include a lower die 21 and an upper die 22. First, the three-dimensional object 10 formed in the above-described forming step is set at a predetermined position in the lower mold 21 (FIG. 2(a)). The lower mold 21 is provided with a convex support portion 21a for supporting the three-dimensional object 10. Next, the lower mold 21 and the upper mold 22 are overlapped to close the molding die 20 (FIG. 2(b)). The molding die 20 may be closed by overlapping the upper mold 22 as a movable mold onto the lower mold 21, or by overlapping the lower mold 21 as a movable mold onto the upper mold 22.

[0052] Next, a paste-like carbon fiber-containing thermosetting resin 11a is filled into the internal cavity 23 through the resin injection port 24 of the upper mold 22 (FIG. 2(c)). This filling step fills the periphery of the three-dimensionally molded object 10 and the hole 10c with the paste-like carbon fiber-containing thermosetting resin 11a. The upper mold 22 may have two or more resin injection ports 24. The upper mold 22 may also have multiple injection paths branching from one resin injection port 24.

[0053] The shape of the hollow portion 23 is such that it has a gap necessary for forming the reinforcing portion 11 of a predetermined thickness on the outer surface of the three-dimensionally shaped object 10 . The molding thickness of the reinforcing portion 11 is not particularly limited and is, for example, 1 mm or more, preferably about 1 mm to 10 mm, and more preferably about 2 mm to 5 mm. The molding thickness of the reinforcing portion 11 can be changed depending on the shape of the hollow portion 23, and it is possible to design the shape of the hollow portion 23 so as to have a desired molding thickness. Furthermore, the molding thickness of the reinforcing portion 11 does not need to be uniform; for example, the thickness of the reinforcing portion 11 molded on the layer side surface 10ba of the outer surface of the three-dimensionally shaped object 10 may be designed to be thicker than the thickness of the other surfaces.

[0054] After filling, the internal temperature of the molding die 20 is raised to a temperature higher than the thermosetting temperature of the carbon fiber-containing thermosetting resin 11a. The molding die 20 may be equipped with a heating / cooling mechanism, or may be placed in a heated atmosphere such as a heating furnace. Then, the paste-like carbon fiber-containing thermosetting resin 11a filled in the periphery including the stack side surface 10ba of the three-dimensionally shaped object 10 and in the hole portion 10c having the stack side surface 10bb is thermally cured all at once to form the reinforcing portion 11 made of the cured carbon fiber-containing thermosetting resin 11b (FIG. 2(d)). After thermal curing, the molding die 20 is opened and the three-dimensional object 10A having the reinforcement portion 11 molded on the outer surface including the stacked side surface 10ba of the three-dimensional object 10 and the hole portion 10c having the stacked side surface 10bb is taken out (Figure 2(e)).

[0055] Thereafter, the three-dimensional object 10A is subjected to processing such as cutting and polishing as required (FIG. 2(f)). In the example shown in Fig. 2(f), a hole of a predetermined size is drilled at the position of the hole 10c in the three-dimensional object 10A using a tool such as an electric drill, thereby forming the hole 11c with the layer side surface 10bb covered with the cured carbon fiber-containing thermosetting resin 11b (reinforcing portion 11). Also, as shown in Fig. 2(f), the corners 11d of the reinforcing portion 11 may be chamfered using a grinding tool or the like. The reinforcing portion 11 contains milled carbon fiber and is excellent not only in strength but also in processability, so that when connecting three-dimensional objects 10A to each other or to other parts, for example, the reinforcing portion 11 can be processed to attach connecting parts such as screws.

[0056] From the viewpoint of improving the mechanical properties of the three-dimensional object 10A, the reinforcing portions 11 are preferably formed on the entire surface (external and internal surfaces) of the three-dimensional object 10, but are not necessarily formed on the entire surface. In another configuration example, depending on the specifications of the three-dimensional object 10, the reinforcing portions 11 may be formed only on the layered side surface 10ba on the outer surface of the three-dimensional object 10, or only on a portion of the layered side surface 10ba on the outer surface of the three-dimensional object 10. In yet another configuration example, the reinforcing portions 11 may not be formed on the layered side surface 10ba on the outer surface of the three-dimensional object 10, but may be formed only on the layered side surface 10bb on the inner surface of a hole 10c or the like formed in the three-dimensional object 10. In any of these configurations, the presence of the reinforcing portions 11 on at least a portion of the layered side surface 10b can have the effect of improving the mechanical properties of the three-dimensional object 10A.

[0057] According to the method for reinforcing a three-dimensional object of the above embodiment, the reinforcing portion 11 made of the hardened carbon fiber-containing thermosetting resin 11b is molded on the outer surface including the stacked side surface 10ba of the three-dimensional object 10 and on the stacked side surface 10bb of the inner surface of the hole 10c. Therefore, the reinforcing portion 11 can improve the mechanical properties (tensile strength, bending strength, impact resistance, hardness) of the three-dimensional object 10A at least in the stacking direction. Furthermore, when a carbon fiber-containing thermosetting resin is used as the reinforcing material-containing resin, the excellent mechanical properties of the carbon fiber contained in the carbon fiber-containing thermosetting resin can further improve the mechanical properties of the three-dimensional object 10A in the stacking direction. Furthermore, when the carbon fiber-containing thermosetting resin contains milled carbon fibers, the mechanical properties of the three-dimensional object 10A can be improved while processing the reinforcing portion 11, for example, cutting processes such as drilling holes and chamfering, thereby improving processability.

[0058] Furthermore, by forming the reinforcing portion 11, it is possible to reliably prevent the occurrence of cracks, fissures, peeling, etc. at the lamination interface 10a of the three-dimensional object 10 located inside the reinforcing portion 11. Furthermore, even if a liquid is flowed under pressure into the hole 11c of the three-dimensional object 10A, the surface of the hole 11c of the three-dimensional object 10A is also covered with the reinforcing portion 11 (hardened carbon fiber-containing thermosetting resin 11b), so it is possible to reliably prevent the liquid from seeping into the layer interface 10a from the hole 10c of the three-dimensional object 10A and the liquid from leaking from the layer interface 10a on the outer surface of the three-dimensional object 10. Therefore, the method for manufacturing a three-dimensional object according to the embodiment can also be applied to the manufacture of parts and the like that are used in environments where stress is applied, thereby expanding the range of applications of three-dimensional objects produced by additive manufacturing technology.

[0059] The present invention is not limited to the above-described embodiment, and various modifications are possible as appropriate, and it goes without saying that these modifications are also included within the scope of the present invention. For example, in the above embodiment, an example was described in which a molding die 20 that is pre-fabricated from metal or the like is used in the reinforcement part molding process, but in another embodiment, the reinforcement part molding process may be performed using a molding device such as that described below.

[0060] 3 is a diagram illustrating a reinforcing portion molding step according to another embodiment. In the figure, 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. Note that components having the same functions as those in the embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and their description will be omitted.

[0061] In another reinforcing portion molding process shown in FIG. 3, a molding device 30 is used. The modeling device 30 has as its main components a modeling tank 31, a laser optical system 32, and a reinforcing material supply system 33. The modeling device 30 has functions such as a function of forming a resin molding die 20A for placing the three-dimensional model 10 by a liquid tank polymerization method, and a function of filling a paste-like carbon fiber-containing thermosetting resin 11a into the molding die 20A in which the three-dimensional model 10 is placed after the molding die 20A has been formed.

[0062] The modeling tank 31 stores, for example, a photocurable resin 26, which is a liquid phase material, and the liquid surface position can be maintained and adjusted at a predetermined position by a photocurable resin adjustment system (not shown). For example, known ultraviolet curable resins such as epoxy or acrylic resins can be used as the photocurable resin 26. A modeling table 35 is provided within the modeling tank 31. The modeling table 35 is used to support the molding die 20A during modeling, and can be moved (raised and lowered) and set to any position by a lifting mechanism (not shown).

[0063] The laser optical system 32 is a mechanism for curing the photocurable resin 26 to form the molding die 20A, and includes an ultraviolet laser light source 32a and a scanning optical system 32b. The ultraviolet laser light source 32a emits ultraviolet laser light 32c, which is an active energy ray. The scanning optical system 32b adjusts the angle at which the ultraviolet laser light 32c emitted from the ultraviolet laser light source 32a is reflected, and irradiates a predetermined range on the liquid surface of the photocurable resin 26 (i.e., the XY plane) with the ultraviolet laser light 32c while scanning it.

[0064] The photocurable resin 26 is cured to a predetermined depth from the liquid surface by irradiation with the ultraviolet laser light 32c. This curing depth can be adjusted within a certain range by adjusting the output of the ultraviolet laser light source 32a, for example, within a range of about 0.1 mm to 0.4 mm.

[0065] Then, by repeatedly irradiating the liquid surface of the photocurable resin 26 with the ultraviolet laser light 32c and adjusting (lowering) the height of the modeling table 35, a molding die 20A made of an ultraviolet curable resin layer and having a predetermined three-dimensional shape (in this case, a box shape with a bottom) is formed, as shown in Fig. 3(a). This molding die 20A functions as a die on which the three-dimensional object 10 is placed. A spacer portion may be formed at the bottom of the molding die 20A to ensure a predetermined gap 23A between the three-dimensional object 10 to be placed.

[0066] The reinforcing material supply system 33 is a mechanism for supplying the carbon fiber-containing thermosetting resin 11a in a fluid state into the molding die 20A, and is equipped with a reinforcing material tank 33a for storing the carbon fiber-containing thermosetting resin 11a, a pump 33b, piping systems 33c and 33d, and a nozzle 34. In the reinforcing material supply system 33, by driving the pump 33b, the carbon fiber-containing thermosetting resin 11a is supplied from the reinforcing material tank 33a through the piping systems 33c and 33d to the nozzle 34, and the carbon fiber-containing thermosetting resin 11a is discharged from the tip of the nozzle 34. The nozzle 34 is movable in the X, Y, and Z axes directions by a nozzle movement mechanism (not shown). The piping system 33d is constructed with a flexible structure and material so as to follow the movement of the nozzle 34. The carbon fiber-containing thermosetting resin 11a has the property of not mixing with the photocurable resin 26 and has a higher specific gravity than the photocurable resin 26. Furthermore, the viscosity of the carbon fiber-containing thermosetting resin 11a is higher than the viscosity of the photocurable resin 26, preferably at least twice the viscosity of the photocurable resin 26.

[0067] As shown in Fig. 3(a), after molding the molding die 20A in the molding tank 31, the three-dimensional object 10 is placed in a submerged state in the molding die 20A with the photocurable resin 26 remaining therein, as shown in Fig. 3(b). A gap 23A corresponding to the above-mentioned cavity 23 is formed between the molding die 20A and the three-dimensional object 10.

[0068] Then, after placing the three-dimensional object 10 in the molding die 20A, the process proceeds to the step of filling the gap 23A between the molding die 20A and the three-dimensional object 10 with carbon fiber-containing thermosetting resin 11a from a nozzle 34, as shown in Figure 3(c). That is, the nozzle 34 is moved into the modeling tank 31 by a nozzle movement mechanism (not shown), and at least the tip (discharge port) of the nozzle 34 is inserted into the photocurable resin 26 remaining in the molding die 20A, and the tip of the nozzle 34 is positioned in the gap 23A. The reinforcing material supply system 33 is then driven to start discharging the carbon fiber-containing thermosetting resin 11a from the tip of the nozzle 34, thereby filling the gap 23A with the carbon fiber-containing thermosetting resin 11a. Because the specific gravity of the carbon fiber-containing thermosetting resin 11a is higher than that of the photocurable resin 26, the carbon fiber-containing thermosetting resin 11a sinks toward the bottom of the molding die 20A, and the photocurable resin 26 remaining in the molding die 20A overflows from the top of the molding die 20A, replacing the photocurable resin 26 in the molding die 20A with the carbon fiber-containing thermosetting resin 11a. During filling, the nozzle 34 may be moved appropriately along the gap 23A.

[0069] 3(b) and 3(c) show a process in which the three-dimensional object 10 is placed in the molding die 20A and then the carbon fiber-containing thermosetting resin 11a is filled into the gap 23A. However, in another process example, the molding die 20A may be first filled with a predetermined amount of the carbon fiber-containing thermosetting resin 11a, the three-dimensional object 10 may be placed in the molding die 20A, and then the carbon fiber-containing thermosetting resin 11a may be further filled.

[0070] After the resin 11a is filled until the top surface of the three-dimensional object 10 is covered with the carbon fiber-containing thermosetting resin 11a, the nozzle 34 is retracted to a predetermined position, and the filling process is completed. Once the filling process is completed, the molding table 35 in the molding tank 31 is raised above the liquid level of the photocurable resin 26, and the molding die 20A filled with the carbon fiber-containing thermosetting resin 11a is removed from the molding table 35, and then the process proceeds to hardening the carbon fiber-containing thermosetting resin 11a in the molding die 20A. After the filling process is completed, the laser optical system 32 and the modeling table 35 may be driven to further model a layer of hardened photocurable resin 26 on the upper surface of the molding die 20A that is covered with the carbon fiber-containing thermosetting resin 11a, thereby sealing the molding die 20A.

[0071] In the curing step, the molding die 20A filled with the carbon fiber-containing thermosetting resin 11a is placed in a heat curing means, for example, a heating furnace 36 having a chamber that can seal the object to be heated, to cure the carbon fiber-containing thermosetting resin 11a. That is, the molding die 20A is placed in the heating furnace 36, and the temperature inside the heating furnace 36 is raised to a temperature higher than the thermosetting temperature of the carbon fiber-containing thermosetting resin 11a, thereby heating the molding die 20A and its interior, causing the curing of the carbon fiber-containing thermosetting resin 11a to proceed, and a reinforcing part 11 made of cured carbon fiber-containing thermosetting resin 11b is molded.

[0072] After the curing step shown in Fig. 3(d) is completed, the molding die 20A is removed from the heating furnace 36, and then the cured layer of the photocurable resin 26 that constitutes the molding die 20A is removed, thereby obtaining a three-dimensional molded object 10B in which the reinforcing portions 11 are molded on the stacked side surface 10b of the three-dimensional molded object 10, as shown in Fig. 3(e). Thereafter, the three-dimensional molded object 10B is subjected to processing such as drilling, cutting, and polishing as necessary.

[0073] The above-described alternative reinforcement portion molding process includes the steps of: forming a resin molding die 20A for placing the three-dimensional object 10 by a liquid vat polymerization method; filling the molding die 20A in which the three-dimensional object 10 is placed with a paste-like carbon fiber-containing thermosetting resin 11a after the molding die 20A is formed; and curing the filled carbon fiber-containing thermosetting resin 11a. Therefore, there is no need to prepare the molding die 20 shown in FIG. 2 in advance, which makes it possible to reduce manufacturing costs, particularly in the case of small-lot, multi-variety production.

[0074] In addition, in the embodiment described using Figures 1 and 2, the case where the molding die 20 is used in the reinforcement part molding process is described, but in yet another embodiment, the following process may be performed without using a die such as the molding die 20. First, the three-dimensional object 10 after the modeling process is immersed in a resin tank filled with a paste-like carbon fiber-containing thermosetting resin. After a predetermined time, the three-dimensional object 10 is taken out of the resin tank. The surface of the three-dimensional object 10 taken out of the resin tank is covered (coated) with a paste-like thermosetting resin containing carbon fiber. Next, in order to harden the paste-like carbon fiber-containing thermosetting resin, the coated three-dimensional object 10 is placed in a heating furnace for thermal hardening. The temperature inside the heating furnace is then raised to a temperature higher than the thermosetting temperature of the carbon fiber-containing thermosetting resin, thereby curing the coated carbon fiber-containing thermosetting resin. After the heat curing, the three-dimensional object 10A with the reinforcing portion 11 formed therein is taken out from the heating furnace.

[0075] In yet another reinforcing portion molding process, a paste-like carbon fiber-containing thermosetting resin may be applied to the surface of the three-dimensional object 10 so as to cover at least a portion of the layered side surface 10b using an applicator such as an applicator roller, and then the object may be placed in a heating furnace for thermosetting to harden the carbon fiber-containing thermosetting resin.

[0076] 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 high strength, such as parts used in various industrial equipment such as automobiles, aircraft, and robots, nursing care products, and sporting goods. [Explanation of symbols]

[0077] 10, 10A, 10B Three-dimensional objects 10a Layer interface 10b, 10ba, 10bb laminated side 10c hole 11 Reinforcement 11a Paste-like thermosetting resin containing carbon fiber 11b Cured carbon fiber-containing thermosetting resin 11c hole 11d Chamfered part 20 Molding mold 21 Lower mold 21a Support part 22 Upper mold 23 Cavity 23A Gap 24 Resin injection port 26 Photocurable resin 30 Three-dimensional modeling equipment 31 Modeling tank 32 Laser optics 32a Ultraviolet laser 32b Scanning optical system 32c Ultraviolet laser light 33 Reinforcement supply system 33a Reinforcement Tank 33b Pump 33c, 33d piping system 34 nozzles 35 Modeling stand 36 Heating Furnace

Claims

1. A method for reinforcing a three-dimensional object formed using additive manufacturing technology, comprising: A method for reinforcing a three-dimensional object, comprising the step of forming a reinforcing portion that covers at least a portion of a layered side surface of the three-dimensional object.

2. 2. The method for reinforcing a three-dimensional object according to claim 1, wherein the reinforcing portion is made of a resin containing a reinforcing material.

3. 3. The method for reinforcing a three-dimensional object according to claim 2, wherein the resin containing a reinforcing material is a thermosetting resin containing carbon fiber.

4. 4. The method for reinforcing a three-dimensional object according to claim 3, wherein the carbon fiber-containing thermosetting resin contains milled carbon fibers.

5. A method for manufacturing a three-dimensional object, comprising: A process of forming a three-dimensional object using additive manufacturing technology; and forming a reinforcing portion that covers at least a portion of the layered side surface of the shaped three-dimensional object.

6. 6. The method for manufacturing a three-dimensional object according to claim 5, further comprising the step of processing the reinforcing portion after the step of forming the reinforcing portion.

7. 7. The method for manufacturing a three-dimensional object according to claim 5, wherein the reinforcing portion is made of a resin containing a reinforcing material.

8. 8. The method for manufacturing a three-dimensional object according to claim 7, wherein the reinforcing material-containing resin is a carbon fiber-containing thermosetting resin.

9. 9. The method for manufacturing a three-dimensional object according to claim 8, wherein the carbon fiber-containing thermosetting resin contains milled carbon fibers.

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