Method for creating three-dimensional shapes, and apparatus for creating three-dimensional shapes.

Abstract

To provide a three-dimensional printing method that can prevent a decrease in the strength of the three-dimensional object being printed, in a so-called core-shell type three-dimensional printing method. [Solution] A method for creating a three-dimensional object, comprising a shell forming step of forming a shell 4, which is the outer shell layer of a three-dimensional object, using a shell material 2, and a core material filling step of filling a core portion 5, which is the part surrounded by the shell 4, with a core material 6, which is a liquid phase material, using a nozzle 14, wherein the method includes a cleaning step of cleaning at least the tip of the nozzle 14 after the core material filling step.

Description

Technical Field

[0001] The present invention relates to a three-dimensional modeling method and a three-dimensional modeling apparatus, and more particularly to a three-dimensional modeling method and a three-dimensional modeling apparatus for modeling a three-dimensional object using an additive manufacturing technology such as 3D printing.

Background Art

[0002] As a name for a manufacturing apparatus using 3D printing technology, the term 3D printer is widely used. A 3D printer calculates the cross-sectional shape of a modeled object by computer based on three-dimensional CAD data, divides the modeled object into thin ring-shaped cross-sectional components, forms the cross-sectional components by various methods, and stacks them to form the target modeled object. 3D printing technology is often used internationally as a synonym for Additive Manufacturing Technology, and the Japanese translation uses additive manufacturing technology.

[0003] In recent years, for modeled objects created by 3D printers, not only appearance but also rigidity and strength are required for evaluation purposes before mass production of actual products, and metal 3D printers and composite material 3D printers have attracted attention. As one of the related technologies, the applicant of this application has proposed a three-dimensional modeling method described in Patent Document 1 below.

[0004] The three-dimensional modeling method described in Patent Document 1 is characterized in that after repeatedly performing shell modeling and core material filling a plurality of times in a modeling tank in which a shell material is stored, the core material is cured collectively by irradiation with active energy rays or application of thermal energy. According to such a three-dimensional modeling method (hereinafter, this method is also referred to as a core-shell modeling method), since there is no lamination interface in the cured core material portion, it is possible to model a three-dimensional object having no directionality in rigidity and strength. [Problems to be Solved by the Invention]

[0005] However, the core-shell 3D printing method described above had some areas that needed improvement to prevent a decrease in the strength of the resulting three-dimensional object. These points will be explained in detail below. Figures 9(a) to 9(d) show the key parts of the intermediate steps in creating a three-dimensional object using the core-shell 3D printing method described above.

[0006] Figure 9(a) shows a scene from the process (core material filling process) in which the core portion 5, which is the part enclosed by the shell 4, is filled with core material 6, which is a liquid phase material, using a nozzle 14. The shell 4 forms the outer shell layer of the three-dimensional object and is formed by hardening a portion of the shell material 2 on a build plate 16 provided in a build tank where the shell material 2 is stored. The core material filling process involves inserting a nozzle 14 into the core section 5, discharging core material 6 from the tip of the nozzle 14, and filling the core section 5 with core material 6. Since core material 6 has a higher specific gravity than shell material 2, the core material 6 is filled into the core section 5 while replacing the shell material 2 inside the core section 5 with the discharged core material 6.

[0007] Once the core material 6 has been filled into the core section 5, the nozzle 14 is moved above the liquid level of the shell material 2, as shown in Figure 9(b). At this time, since the shell material 2 is present on the upper surface of the filled core material 6, when the nozzle 14 is moved above the liquid level of the shell material 2, the shell material 2a may adhere to the tip of the nozzle 14, and the nozzle 14 will be retracted to a predetermined position with the shell material 2a still attached. The shell material 2a may adhere to the side surface of the tip of the nozzle 14, or it may enter the inside of the tip of the nozzle 14.

[0008] Subsequently, as shown in Figure 9(c), a new shell 4 is fabricated on top of the shell 4 filled with core material 6. After fabricating the new shell 4, as shown in Figure 9(d), core material 6 is filled into the core portion 5, which is the part surrounded by the newly fabricated shell 4, using a nozzle 14. Specifically, the nozzle 14, which had been retracted to a predetermined position, is inserted into the core section 5. After inserting the tip of the nozzle 14 into the previously filled core material 6, the core material 6 is discharged from the tip of the nozzle 14, filling the core section 5 with the core material 6.

[0009] At this time, if shell material 2a is attached to the tip of the nozzle 14 which has been retracted to a predetermined position, the shell material 2a at the tip of the nozzle 14 may get mixed into the core material, as shown in Figure 9(d). Furthermore, if the core material filling process is completed with adhering materials such as shell material 2a mixed into the core material 6, and the core material 6 is then hardened in the next core material hardening process, there is a problem that the shell material 2a mixed into the core material 6 will remain in an unhardened state, potentially leading to a decrease in the strength of the fabricated three-dimensional object. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2019-136923 [Overview of the project] Means for solving the problem and their effects

[0011] The present invention has been made in view of the above problems, and aims to provide a three-dimensional molding method and a three-dimensional molding apparatus that can prevent a decrease in the strength of the molded three-dimensional object.

[0012] To achieve the above objective, the three-dimensional molding method (1) according to the present invention is: The shell fabrication process involves creating the outer shell layer of a three-dimensional object using shell material, A method for creating a three-dimensional object, comprising a core material filling step of filling the core portion, which is the part enclosed by the shell, with a core material, which is a liquid phase material, using a nozzle, The method is characterized by including a cleaning step after the core material filling step, in which at least the tip of the nozzle is cleaned.

[0013] According to the above-described three-dimensional molding method (1), since the cleaning step is included, at least the tip of the nozzle can be kept clean after the core material filling step. Therefore, even if the core material filling step is performed again, the core material can be filled into the core portion with the nozzle tip in a clean state, which prevents the phenomenon of deposits on the nozzle tip mixing into the core material and prevents a decrease in the strength of the molded three-dimensional object.

[0014] Furthermore, the three-dimensional molding method (2) according to the present invention is, in the three-dimensional molding method (1) described above, The aforementioned shell molding process, The process includes forming the shell by hardening a portion of the shell material in a molding tank in which the shell material is stored, The aforementioned core material filling step is With the shell positioned below the liquid level of the shell material in the molding tank, the nozzle is inserted into the core portion where the shell material is located, from above the liquid level of the shell material. The core material is discharged from the tip of the nozzle, and with at least the tip of the nozzle inserted into the discharged core material, the core material is filled into the core portion while replacing the shell material. The process includes a step of moving the nozzle above the liquid level of the shell material after filling the core portion with the core material, The cleaning process described above is The method is characterized by including a step of cleaning at least the tip of the nozzle after the moving step.

[0015] According to the above-described three-dimensional molding method (2), even if the shell material adheres to the tip of the nozzle during the movement step, the cleaning step can make at least the tip of the nozzle clean after the movement step. Therefore, even if the core material filling step is performed again, it is possible to prevent the shell material that adhered to the tip of the nozzle from mixing into the core material, thereby preventing a decrease in the strength of the core due to the mixing of the shell material, and thus preventing a decrease in the strength of the molded three-dimensional object.

[0016] Furthermore, the three-dimensional molding method (3) according to the present invention is, in the three-dimensional molding method (1) or (2) described above, The shell forming process and the core material filling process are repeated multiple times. The cleaning process is performed each time the core material filling process is completed.

[0017] According to the above-described three-dimensional molding method (3), the shell molding step and the core material filling step are repeated multiple times, and the cleaning step is performed each time the core material filling step is completed. Therefore, even when the core material filling step is repeated, for example when molding a large object or a complex-shaped object, it is possible to prevent the shell material and other deposits attached to the tip of the nozzle from mixing into the core material. As a result, it is possible to prevent a decrease in the strength of the core due to the mixing of the shell material and other deposits, and to prevent a decrease in the strength of the molded large three-dimensional object or a complex-shaped three-dimensional object.

[0018] Furthermore, the three-dimensional molding method (4) according to the present invention is characterized in that, in any of the three-dimensional molding methods (1) to (3) above, the cleaning step includes a wiping step in which at least the tip of the nozzle is wiped with a wiping part.

[0019] According to the above three-dimensional shaping method (4), since the cleaning step includes the wiping step, by wiping the deposits such as the shell material adhering to at least the tip of the nozzle with the wiping part, at least the tip of the nozzle can be surely made clean. Note that the form such as the material and shape of the wiping part is not particularly limited, and for example, it can be configured to include one or more wiping tools made of a cloth, sponge, rubber, resin, or the like. Further, the wiping part may be a combination of two or more different types of wiping tools.

[0020] Moreover, the three-dimensional shaping method (5) according to the present invention is any one of the above three-dimensional shaping methods (1) to (3), where the cleaning step is a shell material curing step of curing the shell material adhering to the nozzle, and a removing step of removing the cured shell material, and is characterized in that it includes these steps.

[0021] According to the above three-dimensional shaping method (5), the cleaning step includes the shell material curing step and the removing step. Therefore, in the shell material curing step, after curing the shell material adhering to the tip of the nozzle, in the removing step, the cured shell material can be removed. Thus, it can be efficiently removed so that the shell material adhering to the tip of the nozzle does not remain.

[0022] Moreover, the three-dimensional shaping method (6) according to the present invention is the above three-dimensional shaping method (5), where the shell material is cured by irradiation with active energy rays, and the shell material curing step is a step of irradiating at least the tip of the nozzle with the active energy rays to cure the shell material adhering to the nozzle, and is characterized in that it is this step.

[0023] According to the above three-dimensional molding method (6), in the shell material hardening step, the active energy ray is irradiated to at least the tip of the nozzle to harden the shell material adhering to the tip of the nozzle, and then in the removal step, the hardened shell material can be removed. By utilizing the characteristic of the shell material that it hardens when irradiated with the active energy ray, the shell material adhering to at least the tip of the nozzle can be removed efficiently.

[0024] Furthermore, the three-dimensional molding method (7) according to the present invention is characterized in that, in the three-dimensional molding method (5) or (6) above, the removal step includes a step of removing the hardened shell material by sacrificially injecting the core material from the nozzle.

[0025] According to the above-described three-dimensional molding method (7), in the removal step, by sacrificing the core material from the nozzle, even if the shell material has entered the inside of the tip of the nozzle, it can be removed together with the hardened shell material, thereby preventing the shell material from remaining inside the tip of the nozzle.

[0026] Furthermore, the three-dimensional molding method (8) according to the present invention is characterized in that, in the three-dimensional molding method (5) or (6) described above, a test injection step is performed in which the core material is injected from the nozzle before the shell material hardening step.

[0027] According to the above-described three-dimensional molding method (8), even if the shell material has entered the inside of the nozzle tip, the shell material hardening step can be performed after the sacrificial firing step has discharged the shell material that has entered the inside of the nozzle tip, that is, after the shell material is no longer inside the nozzle tip. Therefore, in the shell material hardening step, the shell material adhering to the nozzle can be reliably hardened.

[0028] Furthermore, the three-dimensional modeling apparatus (1) according to the present invention is A shell molding system that creates the outer shell layer of a three-dimensional object using shell material, A three-dimensional molding apparatus comprising a core material filling system for filling the core portion, which is the part surrounded by the molded shell, with a core material, which is a liquid phase material, using a nozzle, The aforementioned shell molding system, The shell is formed by hardening a portion of the shell material in a molding tank in which the shell material is stored. The aforementioned core material filling system With the shell positioned below the liquid level of the shell material in the molding tank, the nozzle is inserted into the core portion where the shell material is located, from above the liquid level of the shell material. The core material is discharged from the tip of the nozzle, and with at least the tip of the nozzle inserted into the discharged core material, the core material is filled into the core portion while replacing the shell material. After filling the core portion with the core material, the nozzle is configured to move above the liquid level of the shell material. The device is characterized by having a cleaning unit that cleans at least the tip of the nozzle, which has been moved above the liquid level of the shell material.

[0029] According to the above-described three-dimensional molding apparatus (1), since it is equipped with a cleaning unit, after filling the core portion with the core material and moving the nozzle above the liquid level of the shell material, at least the tip of the nozzle can be kept clean. Therefore, when filling the core material again, it is possible to prevent any deposits such as the shell material that were attached to the tip of the nozzle from mixing into the inside of the core material. This makes it possible to prevent a decrease in the strength of the core portion due to the mixing of deposits such as the shell material, and thus prevent a decrease in the strength of the molded three-dimensional object.

[0030] Furthermore, the three-dimensional modeling apparatus (2) according to the present invention is, in the three-dimensional modeling apparatus (1) described above, The cleaning unit, The device is characterized by having a wiping section for wiping at least the tip of the nozzle.

[0031] According to the above-described three-dimensional modeling apparatus (2), since the cleaning unit is equipped with the wiping unit, the amount of material such as the shell material adhering to at least the tip of the nozzle can be wiped off with the wiping unit, thereby ensuring that at least the tip of the nozzle is kept clean.

[0032] Furthermore, the three-dimensional modeling apparatus (3) according to the present invention is, in the three-dimensional modeling apparatus (1) described above, The cleaning unit, The nozzle is characterized by having a shell material hardening section that hardens the shell material adhering to at least the tip of the nozzle.

[0033] According to the above-described three-dimensional modeling apparatus (3), since the cleaning unit is equipped with the shell material hardening unit, the shell material adhering to the tip of the nozzle can be hardened in the shell material hardening unit, and then the hardened shell material can be removed. Therefore, the shell material adhering to the tip of the nozzle can be efficiently removed so that no residue remains. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram showing an example of the configuration of a three-dimensional molding apparatus used in the three-dimensional molding method according to Embodiment (1) of the present invention. [Figure 2] (a) to (c) are diagrams illustrating the first shell fabrication step and core material filling step in the three-dimensional fabrication method according to Embodiment (1). [Figure 3] Figures (a) to (d) illustrate an example of the configuration of the cleaning unit and an example of the cleaning process. [Figure 4] (a) to (c) are diagrams illustrating the second shell fabrication step and core material filling step in the three-dimensional fabrication method according to Embodiment (1). [Figure 5] This diagram illustrates an example of the configuration of a cleaning unit in a different form, and an example of a cleaning process. [Figure 6] This figure shows an example of the configuration of the cleaning section in the 3D modeling apparatus according to Embodiment (2), where (a) is a perspective view and (b) is a cross-sectional view taken along line bb in (a). [Figure 7] This is a diagram illustrating an example of the cleaning process performed in the cleaning section. [Figure 8] This is a diagram illustrating another example of the cleaning process performed in the cleaning department. [Figure 9] Figures (a) to (d) show the key parts of the intermediate steps in creating a three-dimensional object using the conventional core-shell 3D printing method. [Modes for carrying out the invention]

[0035] The embodiments of the three-dimensional molding method and three-dimensional molding apparatus according to the present invention will be described below with reference to the drawings. The forms of the three-dimensional molded objects shown in the drawings are schematic representations intended to facilitate understanding of the present invention, and are not limited to these forms.

[0036] Figure 1 is a schematic diagram showing an example of the configuration of a three-dimensional molding apparatus used in the three-dimensional molding method according to the embodiment. In the following description, one direction of the horizontal plane is defined as the X-axis direction, the direction perpendicular to this on the horizontal plane is defined as the Y-axis direction, and the direction perpendicular to the XY plane (horizontal plane) is defined as the Z-axis direction. The 3D printing apparatus 10 functions as a composite material 3D printer and primarily comprises a printing tank 11 where printing is performed by liquid bath photopolymerization, a laser optical system 12, and a core material supply system 13, as well as a cleaning unit 20. In addition, a thermosetting means 17 is used in the 3D printing method according to this embodiment. The shell printing system is configured including the printing tank 11 and the laser optical system 12, and the core material filling system is configured including the core material supply system 13. Including these, an apparatus capable of printing 3D objects using a core-shell printing method is configured.

[0037] Inside the molding tank 11, a photocurable resin, which is a liquid phase material, is stored as the shell material 2, and the liquid level can be maintained and adjusted to a predetermined position by a photocurable resin adjustment system (not shown). For the shell material 2, known ultraviolet curing resins such as epoxy or acrylic resins can be used. A build platform 16 is provided inside the build tank 11. The build platform 16 is for supporting the object being built and can be moved (raised and lowered) and set to any position in the Z-axis direction in the figure by a drive mechanism (not shown).

[0038] The laser optical system 12 comprises an ultraviolet laser light source 12a and a scanning optical system 12b. An ultraviolet laser beam 12c, which is one of the active energy rays, is emitted from the ultraviolet laser light source 12a, and the emitted ultraviolet laser beam 12c can be scanned over a predetermined range on the liquid surface (i.e., the xy plane) of the shell material 2 by driving the scanning optical system 12b.

[0039] When ultraviolet laser light 12c is irradiated onto the shell material 2, the shell material 2 hardens to a predetermined depth from the liquid surface, forming a hardened ultraviolet-cured resin layer 3. This hardening depth can be adjusted within a predetermined range, for example, within a range of about 0.1 mm to 0.4 mm, by adjusting the output of the ultraviolet laser light source 12a.

[0040] Therefore, by positioning the upper surface of the build plate 16 at a depth submerged by a predetermined curing depth from the liquid surface of the shell material 2, leveling the liquid surface of the shell material 2 with a recoater (not shown), and then irradiating an ultraviolet laser beam 12c at any position on the liquid surface of the shell material 2, a cured ultraviolet-curable resin layer 3 of any area is formed on the build plate 16. Subsequently, the build plate 16 is lowered by the curing depth, the liquid surface of the shell material 2 is leveled with the recoater, and then ultraviolet laser light 12c is irradiated onto an arbitrary position on the liquid surface of the shell material 2, so that the cured ultraviolet curing resin layer 3 is laminated on top of the cured ultraviolet curing resin layer 3.

[0041] Then, by repeatedly performing the lowering motion of the build plate 16 and the irradiation of the liquid surface of the shell material 2 with ultraviolet laser light 12c, the cured ultraviolet-curable resin layer 3 is stacked, making it possible to create a three-dimensional object. In this embodiment, the object formed by hardening the shell material 2 in this manner is called the shell 4 (see Figure 2). The shell 4 forms the outer shell layer of the three-dimensional object, and the portion of the shell 4 surrounded by its inner surface that has a bottom surface is called the core portion 5 (see Figure 2).

[0042] The core material supply system 13 comprises a core material tank 13a for storing core material 6, piping systems 13c and 13d connected to the core material tank 13a, a pump 13b installed in the middle of the piping systems 13c and 13d, a nozzle 14 attached to the outlet of the piping system 13d, and a nozzle moving mechanism 15 for moving the nozzle 14.

[0043] The core material supply system 13 is configured to drive a pump 13b to supply core material 6 from the core material tank 13a to the nozzle 14 via piping systems 13c and 13d, and to discharge the core material 6 from the tip of the nozzle 14. The nozzle 14 is composed of, for example, a needle nozzle with a diameter small enough to prevent clogging of the core material 6. The nozzle moving mechanism 15 is composed of, for example, a robot capable of moving and fixing the nozzle 14 in at least the XYZ directions, such as a 3-axis combination robot. Therefore, the piping system 13d is composed of a flexible structure and material so as to follow the movement of the nozzle 14.

[0044] The core material 6 is composed of a composite material in which a reinforcing material is uniformly dispersed in a thermosetting resin, which is a known liquid-phase material such as epoxy or acrylic. The reinforcing material may be a fibrous reinforcing material containing at least one of carbon fibers, glass fibers, and aramid fibers, or it may be an inorganic material powder such as silica. The reinforcing material is preferably carbon fiber, and more preferably contains milled carbon fibers which are short fibers with a length of 200 μm or less. Furthermore, the specific gravity of the core material 6 is higher than the specific gravity of the shell material 2, and the viscosity of the core material 6 is higher than the viscosity of the shell material 2, preferably at least twice the viscosity of the shell material 2.

[0045] The thermosetting means 17 is used in the process of curing the core material 6 filled in the core portion 5 (core material curing process), and consists of a heating furnace having a sealable chamber. The thermosetting means 17 is capable of raising and lowering the temperature inside the heating furnace to a temperature higher than the thermosetting temperature of the core material 6.

[0046] The operation of each part of the 3D printing apparatus 10 (the build plate 16, the laser optical system 12, the core material supply system 13, and the cleaning unit 20) is controlled by a control unit (not shown). This control unit consists of a computer device including an arithmetic processing unit and a memory unit. The memory unit stores programs for controlling the operation of each part of the 3D printing apparatus 10, 3D shape data (CAD data) of the 3D object to be printed, and various other setting data necessary for printing. The arithmetic processing unit executes processes to control the operation of each part of the 3D printing apparatus 10 based on the above programs.

[0047] Next, an example of a three-dimensional molding method according to the embodiment will be explained using Figures 2 to 4. The three-dimensional molding method according to the embodiment includes a shell molding step of molding a shell 4, which is the outer shell layer of the three-dimensional molded object, using a shell material 2; a core material filling step of filling a core portion 5, which is the part surrounded by the shell 4, with a core material 6 using a nozzle 14; and a cleaning step of cleaning at least the tip of the nozzle 14 after the core material filling step. The three-dimensional molding method according to the embodiment further includes a core material hardening step of hardening the core material 6 inside the core portion 5.

[0048] The 3D modeling method described below involves dividing the shell modeling process and the core material filling process into two stages and repeating them, with a cleaning process performed each time the core material filling stage is completed.

[0049] Figures 2(a) to 2(c) are diagrams illustrating the first shell fabrication step and core material filling step included in the three-dimensional fabrication method according to the embodiment, and are enlarged partial cross-sectional views of the peripheral area of ​​the build plate 16.

[0050] The shell forming process, as shown in Figure 2(a), is a process in which a shell 4 is formed by hardening a portion of the shell material 2 in a forming tank 11 where the shell material 2 is stored. More specifically, the shell fabrication process involves moving the nozzle 14 of the core material supply system 13 out of the irradiation range of the ultraviolet laser light 12c, and then fabricating a shell 4 on the fabrication table 16 using the photopolymerization reaction of the shell material 2 by irradiating the liquid surface of the shell material 2 with light using the laser optical system 12 and lowering the fabrication table 16.

[0051] In other words, in the shell fabrication process, based on the three-dimensional shape data of the shell 4, the process alternates between scanning and irradiating the liquid surface of the shell material 2 on the build plate 16 with ultraviolet laser light 12c and lowering the build plate 16 by the amount of the curing depth, thereby fabricating the shell 4 on the build plate 16 as shown in Figure 2(a). The shell 4 shown in Figure 2 is fabricated in the shape of a bottomed box with an opening on the top surface.

[0052] After the first shell 4 is fabricated, with the shell 4 positioned below the liquid level of the shell material 2 in the fabrication tank 11, the process then proceeds to the first core material filling step shown in Figures 2(b) and (c). The core material filling process involves positioning the shell 4 below the liquid level of the shell material 2 in the molding tank 11, inserting the nozzle 14 into the core section 5 where the shell material 2 is located from above the liquid level of the shell material 2, discharging the core material 6 from the tip of the nozzle 14, and filling the core section 5 with the core material 6 while at least the tip of the nozzle 14 is inserted into the discharging core material 6, replacing the shell material 2 with the core material 6. The filling of the core material 6 may also be performed by moving the nozzle 14 horizontally (XY axis) and vertically (Z axis) within the core section 5 using a nozzle moving mechanism 15.

[0053] As shown in Figure 2(b), the core material filling process is carried out with the shell 4 positioned below the liquid level of the shell material 2 in the molding tank 11, and the shell material 2 is present in the core section 5 before the core material 6 is filled. Therefore, as the core material 6, which has a higher specific gravity than the shell material 2, is filled into the core section 5, the shell material 2 in the core section 5 is pushed up and pushed out of the shell 4 through the upper opening of the shell 4, and the inside of the core section 5 is replaced from shell material 2 to core material 6.

[0054] Then, as shown in Figure 2(c), after filling the core portion 5, which is the part surrounded by the inner surface of the first shell 4, with a predetermined amount of core material 6, the discharge of core material 6 from the nozzle 14 is stopped, and the nozzle 14 is moved above the liquid surface of the shell material 2 and retracted to a predetermined position (movement step).

[0055] Furthermore, as shown in Figure 2(c), when the nozzle 14 is moved above the liquid level of the shell material 2, the shell material 2a may adhere to the tip of the nozzle 14. Therefore, in this embodiment, a cleaning process is then performed in the cleaning unit 20.

[0056] Figures 3(a) to 3(d) illustrate an example of the cleaning process performed in the cleaning unit 20. First, an example of the configuration of the cleaning unit 20 will be described. The cleaning unit 20 is comprised of a wiping cleaner 21, which is an example of a wiping unit. As shown in Figure 3(a), the wipe cleaner 21 includes a pair of wipe pads 22 and 23, and a pad support section 25 that movably supports these wipe pads 22 and 23 so as to be in contact with and separated from each other.

[0057] The pad support section 25 comprises a support base 26 and a linear motion section 27 disposed on the support base 26, with a pair of wiping pads 22 and 23 attached to the linear motion section 27. The linear motion section 27 is composed of a linear motion mechanism including a sliding section 28 that slides the pair of wiping pads 22 and 23 in a direction that brings them into contact with each other and separates them.

[0058] The wiping pads 22 and 23 are examples of wiping tools and can be made of various materials that are flexible, elastic, and / or absorbent, such as cloth, sponge, rubber (silicone rubber or polyurethane rubber), or resin. Their shape can also be any shape that can hold the nozzle 14.

[0059] Figure 3(b) shows an example configuration in which the wipe cleaner 21 is attached to the horizontal movement mechanism 31. The horizontal movement mechanism 31 includes a linear motion mechanism that can move a pair of wiping pads 22 and 23 back and forth in a horizontal direction (X-axis direction) parallel to their opposing surfaces. In this configuration example, with the nozzle 14 sandwiched between the pair of wiping pads 22 and 23, it is possible to move the pair of wiping pads 22 and 23 back and forth in a horizontal direction parallel to their opposing surfaces.

[0060] Figure 3(c) shows an example configuration in which the wipe cleaner 21 is attached to the vertical movement mechanism 32. The vertical movement mechanism 32 includes a linear motion mechanism that can move a pair of wiping pads 22 and 23 back and forth in the vertical direction. In this configuration example, with the nozzle 14 sandwiched between the pair of wiping pads 22 and 23, it is possible to move the pair of wiping pads 22 and 23 back and forth in the vertical direction. Alternatively, the horizontal movement mechanism 31 and the vertical movement mechanism 32 may be combined.

[0061] Figure 3(d) shows an example configuration in which the wipe cleaner 21 is attached to the rotating mechanism 33. The rotating mechanism 33 is configured to rotate the wiping cleaner 21 around the axis of the nozzle 14 sandwiched between a pair of wiping pads 22 and 23. In this configuration, the wiping cleaner 21 can be rotated with the nozzle 14 sandwiched between the pair of wiping pads 22 and 23. The rotating mechanism 33 may also be configured to reciprocate vertically in addition to its rotational motion.

[0062] The cleaning process includes a wiping step in which the shell material 2a adhering to at least the tip of the nozzle 14 is wiped off with a wiping cleaner 21. In the wiping process, after the core material is filled, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 (Figure 2(c)), which has been moved above the liquid surface of the shell material 2, between the pair of wiping pads 22 and 23 of the wiping cleaner 21 (Figure 3(a)). At this stage, the pair of wiping pads 22 and 23 are positioned spaced apart from each other.

[0063] When the nozzle 14 is positioned between the pair of wiping pads 22 and 23, the operation of the linear motion section 27 of the pad support section 25 is controlled by the control unit, causing the slide section 28 to move in a direction that brings the opposing surfaces of the pair of wiping pads 22 and 23 into contact. This sets the nozzle 14 in a state where it is sandwiched between the pair of wiping pads 22 and 23. At this time, the opposing surfaces of the pair of wiping pads 22 and 23 are pressed against each other.

[0064] Next, a wiping operation is performed by a pair of wiping pads 22 and 23 in one of the configurations shown in Figures 3(b), (c), and (d). In the configuration example shown in Figure 3(b), the pair of wiping pads 22 and 23 reciprocate horizontally (in the X-axis direction) to wipe off the shell material 2a adhering to the nozzle 14. In the configuration example shown in Figure 3(c), the pair of wiping pads 22 and 23 reciprocate vertically (in the Z-axis direction) to wipe off the shell material 2a adhering to the nozzle 14. In the configuration example shown in Figure 3(d), the pair of wiping pads 22 and 23 rotate to wipe off the shell material 2a adhering to the nozzle 14. Note that a combination of any of the configurations shown in Figures 3(b), (c), and (d) may also be used. For example, the configurations shown in Figure 3(b) and Figure 3(c) may be combined to create a configuration in which a pair of wiping pads 22 and 23 move in the X-axis and Z-axis directions. Alternatively, the configurations shown in Figure 3(c) and Figure 3(d) may be combined to create a configuration in which a pair of wiping pads 22 and 23 move and rotate in the Z-axis direction.

[0065] Once the wiping operation by the pair of wiping pads 22 and 23 is completed, the operation of the linear motion part 27 of the pad support part 25 is controlled, and the sliding part 28 moves in a direction that separates the opposing surfaces of the pair of wiping pads 22 and 23, thus ending the cleaning process.

[0066] Next, as shown in Figures 4(a) to 4(c), the process proceeds to the second shell fabrication step and the core material filling step. The second shell fabrication process, as shown in Figure 4(a), is similar to the first process. It involves moving the nozzle 14 of the core material supply system 13 out of the irradiation range of the ultraviolet laser light 12c, and then using the laser optical system 12 to irradiate the liquid surface of the shell material 2 and lowering the build plate 16 to fabricate a new shell 4 on top of the shell 4 fabricated in the first shell fabrication process using the photopolymerization reaction of the shell material 2. The cleaning process after the first core material filling and the second shell fabrication process may be performed in parallel.

[0067] After creating the second shell 4, with the shell 4 positioned below the liquid level of the shell material 2 in the build tank 11, the process then proceeds to the second core material filling step shown in Figures 4(b) and 4(c). The second core material filling process is the same as the first, in which the shell 4 is placed below the liquid level of the shell material 2 in the molding tank 11, the nozzle 14 which has been cleaned in the cleaning process is inserted into the core section 5 where the shell material 2 is located from above the liquid level of the shell material 2, and then inserted into the previously filled core material 6, after which the core material 6 is discharged from the tip of the nozzle 14.

[0068] In the scene shown in Figure 4(b), the shell material 2a that was attached to the nozzle 14 after the first core material filling is removed in the cleaning process. Therefore, in the second core material filling process, when the nozzle 14 is inserted into the core section 5 where the shell material 2 is present from above the liquid level of the shell material 2, and then inserted into the previously filled core material 6, and the core material 6 is discharged from the tip of the nozzle 14, the shell material 2a that was attached to the nozzle 14 does not get mixed into the core material 6.

[0069] Then, as shown in Figure 4(c), after filling the core portion 5, which is the part surrounded by the inner surface of the second shell 4, with a predetermined amount of core material 6, the discharge of core material 6 from the nozzle 14 is stopped, and the nozzle 14 is moved above the liquid level of the shell material 2 to complete the core material filling process. Subsequently, the same cleaning process as described above is performed in the cleaning unit 20 to remove the shell material 2a adhering to the nozzle 14.

[0070] Furthermore, after the core material filling process is completed, the build plate 16 is moved above the liquid level of the shell material 2, the shell 4 with the core material 6 filled inside is removed from the build plate 16, and the process proceeds to the core material hardening process. In the core material hardening process, the shell 4 removed from the build plate 16 is placed into the heat hardening means 17 to start the heat hardening process of the core material 6. In other words, the shell 4 is placed inside the heat curing means 17, and the temperature inside the heat curing means 17 is raised to a temperature higher than the heat curing temperature of the core material 6. This heats up the entire three-dimensional object, including the core material 6 and the shell 4, causing the entire core material 6 to harden all at once. After the entire core material 6 has hardened, the three-dimensional object consisting of the hardened core material 6 and shell 4 is removed from the heat curing means 17, thus ending the core material hardening process. The hardened core material 6 that constitutes the three-dimensional object has no layering interface, and the hardened core material 6 does not contain any unhardened shell material 2a.

[0071] The above 3D printing method describes an example where the shell printing process and the core material filling process are performed alternately twice each. However, depending on the shape of the 3D object to be printed, the shell printing process and the core material filling process may be performed alternately only once, or they may be performed alternately three or more times. In all cases, the cleaning process should be performed after each core material filling step.

[0072] According to the three-dimensional molding method of the above embodiment, a cleaning process is performed each time the core material filling process is completed, so that at least the tip of the nozzle 14 can be kept clean after the core material filling process. Therefore, even when repeatedly performing the shell molding process and the core material filling process to create, for example, a large three-dimensional object or a three-dimensional object with a complex core part 5 shape, the tip of the nozzle 14 can remain clean while the core material 6 is filled into the core part 5, preventing any deposits such as shell material 2a adhering to the tip of the nozzle 14 from mixing into the core material 6. This makes it possible to prevent a decrease in the strength of the core portion 5, i.e., the core material 6 after hardening, due to the mixing of shell material 2a adhering to the nozzle 14, and thus prevent a decrease in the strength of the fabricated three-dimensional object.

[0073] Furthermore, according to the above three-dimensional molding method, since the cleaning process includes a wiping process, at least the tip of the nozzle 14 can be reliably cleaned by wiping off any attached material such as shell material 2a with the wiping cleaner 21, that is, by physical contact and friction. In the embodiment described above, the case in which shell material 2a adheres to the tip of the nozzle 14 was explained. However, when the nozzle 14 is moved above the liquid level of the shell material 2, core material 6 may also adhere to the tip of the nozzle 14. In this case as well, the nozzle 14 can be made clean by performing the cleaning process described above.

[0074] Furthermore, according to the embodiment of the 3D printing apparatus 10, since it is equipped with a cleaning unit 20, after filling the core part 5 with core material 6 and moving the nozzle 14 above the liquid surface of the shell material 2, at least the tip of the nozzle 14 can be kept clean. Therefore, when filling the core material 6 next, it is possible to prevent the shell material 2a adhering to the tip of the nozzle 14 from mixing into the inside of the core material 6. This makes it possible to prevent a decrease in the strength of the core part 5 due to the mixing of shell material 2a adhering to the nozzle 14, and thus prevent a decrease in the strength of the printed 3D object.

[0075] Furthermore, with the above-described three-dimensional modeling apparatus 10, since the cleaning unit 20 is equipped with a wiping cleaner 21, any deposits such as shell material 2a adhering to at least the tip of the nozzle 14 can be wiped off with the wiping pads 22 and 23, that is, at least the tip of the nozzle 14 can be reliably kept clean through physical contact and friction.

[0076] Furthermore, the wiping pads 22 and 23 of the wiping cleaner 21 may be made of material impregnated with a cleaning solution or stripping solution for shell material, or the process may include immersing at least the tip of the nozzle 14 in a cleaning solution or dissolving solution for shell material before the wiping process with the wiping cleaner 21. In addition, the cleaning unit 20 may be made up of two or more wiping cleaners 21.

[0077] Furthermore, the wiping section constituting the cleaning section 20 is not limited to the configuration of the wiping cleaner 21 shown in Figures 3(b), (c), and (d). In another configuration example, instead of providing the horizontal movement mechanism 31, the vertical movement mechanism 32, or the rotation mechanism 33, the nozzle 14 may be sandwiched between a pair of wiping pads 22 and 23, and then the nozzle 14 may be moved horizontally and / or vertically along the joint surface of the pair of wiping pads 22 and 23 by the nozzle movement mechanism 15. In yet another configuration example, instead of the pair of wiping pads 22 and 23, a rotating pad with a circular cross-section may be used, and its outer circumferential surface may be in contact with at least the tip of the nozzle 14 while rotating around the nozzle 14. In yet another configuration example, the cleaning unit 20 may be configured to include a cleaning mechanism for cleaning the wipe cleaner 21. This cleaning mechanism may include, for example, a flushing device that can be disposed between a pair of wipe pads 22 and 23, and the flushing device may be configured to absorb deposits such as shell material 2a attached to the pair of wipe pads 22 and 23. Alternatively, the flushing device may spray cleaning liquid onto the pair of wipe pads 22 and 23 and then absorb the deposits along with the cleaning liquid. Furthermore, the cleaning mechanism may consist of a cleaning roller or the like that wipes off deposits such as shell material 2a attached to the pair of wipe pads 22 and 23.

[0078] Furthermore, instead of the wipe cleaner 21, a wipe cleaner 21A relating to another configuration example, as shown in Figure 5, may be used. The wipe cleaner 21A is composed of a wipe block 24. The wiping block 24 is composed of a block-shaped member made of various materials that have flexibility, elasticity, and / or liquid absorption properties, such as sponge, rubber such as silicone rubber or polyurethane rubber, or resin.

[0079] The wiping block 24 has a wiping slit 24a that allows the nozzle 14 to be moved at least within the XY plane while at least the tip of the nozzle 14 is inserted into it. The width of the wiping slit 24a is narrower than the outer diameter of the nozzle 14, making it possible to clamp the nozzle 14 with the wiping slit 24a. The wiping slit 24a is formed in a U-shape in plan view, but the shape of the wiping slit 24a is not particularly limited as long as it is a shape that allows the entire outer surface of the nozzle 14 to come into contact with the inner surface of the wiping slit 24a, such as an L-shape in plan view.

[0080] In the cleaning process using the wipe cleaner 21A (wiping process), after the core material has been filled, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 (Figure 2(c)), which has been moved above the liquid surface of the shell material 2, to just before the slit inlet 24b of the wiping block 24.

[0081] Next, the control unit controls the operation of the nozzle movement mechanism 15 to insert the tip of the nozzle 14 through the slit inlet 24b, and then moves the nozzle 14 horizontally (in the X-axis direction, Y-axis direction, and then the X-axis direction again) along the shape of the wiping slit 24a (U-shape) (i.e., performs a wiping operation). After that, the nozzle 14 is removed from the slit outlet 24c, and the wiping process is completed. In the configuration example shown in Figure 5, the shell material 2a adhering to the nozzle 14 is wiped away by moving the nozzle 14 along the wiping slit 24a of the wiping block 24.

[0082] Next, a three-dimensional molding method according to embodiment (2) and a three-dimensional molding apparatus used in said three-dimensional molding method will be described. The three-dimensional molding apparatus 10A (see Figure 1) used in the three-dimensional molding method according to embodiment (2) differs from the three-dimensional molding apparatus 10 according to embodiment (1) shown in Figure 1 in its cleaning unit 20A. Since the other components are substantially the same, components with the same function are denoted by the same reference numerals, and their descriptions are omitted.

[0083] Figure 6 shows an example of the configuration of the cleaning unit 20A included in the 3D printing apparatus 10A according to embodiment (2), where (a) is a perspective view and (b) is a cross-sectional view taken along line bb in (a). The cleaning unit 20A includes a shell material hardening unit 40, which is an example of a shell material hardening unit that hardens the shell material 2a adhering to at least the tip of the nozzle 14. Furthermore, the cleaning unit 20A includes a recovery unit 45 for recovering core material 6 and other materials that have been discarded from the nozzle 14. The shell material hardening unit 40 and the recovery unit 45 are located adjacent to each other.

[0084] The shell material curing unit 40 comprises a nozzle housing case 41 capable of accommodating at least the tip of the nozzle 14, and a light irradiator 42 disposed within the nozzle housing case 41. The nozzle housing case 41 is a housing with a roughly rectangular parallelepiped shape and is equipped with a nozzle housing opening 41a for inserting and removing the nozzle 14. The nozzle housing opening 41a is, for example, a narrow strip-shaped opening formed from the top surface to one side of the nozzle housing case 41.

[0085] Furthermore, as shown in Figure 6(b), one or more light irradiators 42 are arranged inside the nozzle housing case 41, for example, on the lower inner surface and the bottom surface. The light irradiator 42 is used to cure the shell material 2a (see Figures 2 and 4) attached to the tip of the nozzle 14 housed in the nozzle housing case 41 using light energy, and is composed of, for example, a UV irradiator including an ultraviolet (UV) LED light source or a UV lamp light source.

[0086] Figure 7 is a diagram illustrating an example of the cleaning process performed in the cleaning unit 20A. The cleaning process performed in the cleaning section 20A includes a shell material hardening process (Figure 7(a), (b)) for hardening the shell material 2a adhering to the nozzle 14, and a removal process (Figure 7(c), (d)) for removing the hardened shell material 2a.

[0087] In the shell material hardening process, after the core material is filled, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 (Figures 2(c), 4(c)), which has been moved above the liquid surface of the shell material 2, to the front of the nozzle housing opening 41a of the nozzle housing case 41 (Figure 7(a)). Next, the control unit controls the operation of the nozzle movement mechanism 15 to house the nozzle 14 from the nozzle housing opening 41a into the nozzle housing case 41, and then drives the light irradiator 42 to irradiate at least the tip of the nozzle 14 with UV light to harden the shell material 2a attached to the nozzle 14 (Figure 7(b)).

[0088] After the shell material 2a attached to the nozzle 14 has hardened, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 from the nozzle housing case 41 onto the recovery unit 45 (Figure 7(c)). Subsequently, the control unit controls the operation of the core material supply system 13 to discharge a predetermined amount of core material 6 from the nozzle 14. This discharge of core material 6 removes the hardened shell material 2a along with the discharged core material 6 from the nozzle 14 and is collected in the recovery unit 45 (Figure 7(d)).

[0089] According to the three-dimensional molding method of embodiment (2), the cleaning step includes a shell material hardening step and a removal step. Therefore, in the shell material hardening step, UV light is irradiated to at least the tip of the nozzle 14 to harden the shell material 2a adhering to the tip of the nozzle 14, and then in the removal step, the hardened shell material 2a can be removed. By utilizing the characteristic of the shell material 2 that it hardens when irradiated with UV light, the shell material 2a adhering to the tip of the nozzle 14 can be efficiently removed so that no residue remains.

[0090] Furthermore, according to the above three-dimensional molding method, in the removal step, by sacrificially inserting core material 6 from the nozzle 14, even if shell material 2a adhering to the inside of the tip of the nozzle 14 has entered, it can be removed together with the hardened shell material 2a, thereby preventing shell material 2a from remaining inside the tip of the nozzle 14. After the removal step, a wiping step may be included in which at least the tip of the nozzle 14 is wiped. In addition, in the removal step according to another embodiment, instead of sacrificially inserting core material 6, an external force may be applied to the hardened shell material 2a to remove the shell material 2a, or after the shell material 2a has been removed by applying an external force, or after the shell material 2a has been made easier to remove by applying an external force, a sacrificial insert of core material 6 may be performed again. The method of applying an external force to the shell material 2a may be, for example, a grinding process to remove the shell material 2a, or a scraping method to remove the shell material 2a.

[0091] Furthermore, with the above-described three-dimensional modeling apparatus 10A, the cleaning unit 20A is equipped with a shell material hardening unit 40. This allows the shell material 2a adhering to the tip of the nozzle 14 to be hardened by the shell material hardening unit 40, and then the hardened shell material 2a can be removed. Therefore, the shell material 2a adhering to the tip of the nozzle 14 can be efficiently removed so that no residue remains.

[0092] Furthermore, the cleaning process using the shell material hardening unit 40 described above is not limited to the configuration explained with reference to Figure 7, and it is possible to change the processes before and after the shell material hardening process using the shell material hardening unit 40.

[0093] Figure 8 is a diagram illustrating the cleaning process related to a modified example using the shell material hardening unit 40. The cleaning process according to the modified example includes a test run step (Figure 8(a), (b)) in which core material 6 is test-fired from the nozzle 14, a shell material hardening step (Figure 8(c)) in which the shell material 2a adhering to the nozzle 14 after the test run hardens, and a removal step (Figure 8(d), (e)) in which the hardened shell material 2a is removed.

[0094] First, in the test injection process, after the core material is filled, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 (Figures 2(c), 4(c)), which has been moved above the liquid level of the shell material 2, onto the recovery section 45 (Figure 8(a)). Next, the control unit controls the operation of the core material supply system 13 to discharge a predetermined amount of core material 6 from the nozzle 14. This discharge of core material 6 removes a portion of the shell material 2a adhering to the tip of the nozzle 14 along with the discharged core material 6, and is collected in the recovery unit 45 (Figure 8(d)).

[0095] The next step in the shell material hardening process involves moving the nozzle 14 (Figures 2(c) and 4(c)), located above the recovery unit 45, into the nozzle housing case 41 through the nozzle housing opening 41a, and then driving the light irradiator 42 to irradiate at least the tip of the nozzle 14 with UV light to harden the shell material 2a attached to the nozzle 14 (Figure 8(c)).

[0096] After the shell material 2a attached to the nozzle 14 has hardened, the control unit controls the operation of the nozzle moving mechanism 15 to move the nozzle 14 from the nozzle housing case 41 onto the recovery unit 45 (Figure 8(d)). Next, the control unit controls the movement of a pair of scraping pads 46 and 47 located above the recovery unit 45, so that the pair of scraping pads 46 and 47 grip the portion of the nozzle 14 above the tip (Figure 8(d)). The pair of scraping pads 46 and 47 are attached to a linear motion unit (not shown) and are slidable in directions that bring the pair of scraping pads 46 and 47 into contact with each other and separate them.

[0097] Subsequently, the control unit controls the operation of the nozzle movement mechanism 15 to move the nozzle 14 upward (Figure 8(e)). Through the gripping action of the pair of scraping pads 46 and 47 shown in Figures 8(d) and (e), and the lifting action of the nozzle 14, the hardened shell material 2a adhering to the tip of the nozzle 14 is scraped off by the pair of scraping pads 46 and 47 and collected in the collection unit 45. The scraping pads 46 and 47 may also function as wiping pads.

[0098] According to the three-dimensional molding method including the cleaning step described above, even if shell material 2a has entered the inside of the tip of the nozzle 14 after it has been pulled up from the molding tank 11 after the core material has been filled, the shell material hardening step can be performed after the shell material 2a that has entered the inside of the tip of the nozzle 14 has been discharged by the discard step, that is, after the shell material 2a has been removed from at least the tip of the nozzle 14. Therefore, in the shell material hardening step, it is possible to reliably harden the shell material 2a adhering to the nozzle 14, and the hardened shell material 2a adhering to the tip of the nozzle 14 can be reliably removed by the subsequent step of removing the shell material 2a using a pair of scraping pads 46 and 47.

[0099] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible, all of which are also included within the scope of the present invention. For example, at least the tip of the nozzle 14 of the three-dimensional molding apparatus 10, 10A described above may be subjected to a surface treatment to impart liquid repellency to the shell material 2 and core material 6. This surface treatment includes various surface treatments that can impart release properties (non-adhesion), and includes, for example, coating treatments using resins such as fluorine or silicone, nanoparticles, other liquid repellents, liquid repellent paints, water-repellent plating treatments such as electroless nickel plating, surface processing treatments that form fine irregularities on the surface, or combinations thereof. Furthermore, the above surface treatment may be applied not only to the outer surface of the nozzle 14 but also to the inner surface of the nozzle 14 (inside the nozzle hole). Such surface treatments can enhance the effect of suppressing the adhesion of the shell material 2 and core material 6 to the nozzle 14, and facilitating the wiping and removal of the shell material 2 and core material 6 that have adhered to the nozzle 14.

[0100] The present invention is widely applicable in the field of additive manufacturing technologies such as 3D printers. By applying the present invention to such fields, it becomes possible not only to prototype but also to mass-produce parts and products that require lightweight 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]

[0101] 1 Three-dimensional object 2 Shell material 2a Adhesive shell material 3. Cured UV-cured resin layer 4 Shells 5. Core 6 Core material 10, 10A 3D Modeling Device 11 Modeling tank 12 Laser Optics 12a Ultraviolet laser light source 12b Scanning optical system 12c ultraviolet laser light 13 Core material supply system 13a Core material tank 13b Pump 13c, 13d Piping System 14 nozzles 15. Nozzle movement mechanism 16. Build Table 17 Heat curing means 20, 20A Cleaning Section 21, 21A Wipe-off Cleaner 22, 23 Wiping pads 24 Wiping blocks 24a Wiping slit 24b Slit entrance 24c slit outlet 25 Pad support section 26 Support stand 27 Linear motion section 28 Slide section 31 Horizontal movement mechanism 32 Vertical movement mechanism 33 Rotation mechanism 40 Shell material hardening unit 41 Nozzle storage case 41a Nozzle housing 42 UV irradiator 45. Recovery Section 46, 47 Scratching pads

Claims

1. The shell fabrication process involves creating the outer shell layer of a three-dimensional object using shell material, A method for creating a three-dimensional object, comprising a core material filling step of filling the core portion, which is the part enclosed by the shell, with a core material, which is a liquid phase material, using a nozzle, A method for creating three-dimensional shapes, characterized by including a cleaning step of cleaning at least the tip of the nozzle after the core material filling step.

2. The aforementioned shell molding process, The process includes forming the shell by hardening a portion of the shell material in a molding tank in which the shell material is stored, The aforementioned core material filling step is With the shell positioned below the liquid level of the shell material in the molding tank, the nozzle is inserted into the core portion where the shell material is located, from above the liquid level of the shell material. The core material is discharged from the tip of the nozzle, and with at least the tip of the nozzle inserted into the discharged core material, the core material is filled into the core portion while replacing the shell material. The process includes a step of moving the nozzle above the liquid level of the shell material after filling the core portion with the core material, The cleaning process described above is The method for creating a three-dimensional object according to claim 1, characterized in that it includes a step of cleaning at least the tip of the nozzle after the moving step.

3. The shell forming process and the core material filling process are repeated multiple times. The method for creating a three-dimensional object according to claim 1 or 2, characterized in that the cleaning step is performed each time the core material filling step is completed.

4. The cleaning process described above is The method for creating a three-dimensional object according to claim 1 or 2, characterized in that it includes a wiping step of wiping at least the tip of the nozzle with a wiping section.

5. The cleaning process described above is A shell material hardening step for hardening the shell material adhering to the nozzle, A method for creating a three-dimensional object according to claim 1 or 2, characterized by including a removal step of removing the hardened shell material.

6. The aforementioned shell material hardens upon irradiation with active energy rays. The aforementioned shell material hardening process, The method for creating a three-dimensional object according to claim 5, characterized in that it includes the step of irradiating at least the tip of the nozzle with the active energy ray to harden the shell material attached to the nozzle.

7. The method for creating a three-dimensional object according to claim 5, characterized in that the removal step includes a step of removing the hardened shell material by sacrificially injecting the core material from the nozzle.

8. The method for creating a three-dimensional object according to claim 5, characterized in that it includes a test injection step in which the core material is injected from the nozzle before the shell material hardening step.

9. A shell molding system that creates the outer shell layer of a three-dimensional object using shell material, A three-dimensional molding apparatus comprising a core material filling system for filling the core portion, which is the part surrounded by the molded shell, with a core material, which is a liquid phase material, using a nozzle, The aforementioned shell molding system, The shell is formed by hardening a portion of the shell material in a molding tank in which the shell material is stored. The aforementioned core material filling system With the shell positioned below the liquid level of the shell material in the molding tank, the nozzle is inserted into the core portion where the shell material is located, from above the liquid level of the shell material. The core material is discharged from the tip of the nozzle, and with at least the tip of the nozzle inserted into the discharged core material, the core material is filled into the core portion while replacing the shell material. After filling the core portion with the core material, the nozzle is configured to move above the liquid level of the shell material. A three-dimensional molding apparatus characterized by comprising a cleaning unit for cleaning at least the tip of the nozzle that has been moved above the liquid surface of the shell material.

10. The cleaning unit, The three-dimensional molding apparatus according to claim 9, characterized in that it is provided with a wiping section for wiping at least the tip of the nozzle.

11. The cleaning unit, The three-dimensional molding apparatus according to claim 9, further comprising a shell material hardening section for hardening the shell material attached to at least the tip of the nozzle.

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