JP7270892B2 - Method and apparatus for creating three-dimensional objects - Google Patents

Description

The present invention relates to a method and apparatus for producing a three-dimensional object with a predetermined design, and in particular, by applying the so-called 3D printer technology, in which the object is modeled by spraying onto a conventional substrate, and is temporarily fluidized by thermal or mechanical action. The present invention relates to a method of forming a three-dimensional object by ejecting resin or the like into a medium and a manufacturing apparatus therefor.

Although 3D printers are defined as Additive Manufacturing in ASTM F2792-12a, the term 3D printers is used herein for general ease of understanding. 3D printer technology can be divided into five elemental technologies: materials, manufacturing methods, systems, individual technologies for each manufacturing method, and application technologies.

As for "materials", which is one of the elemental technologies, various materials have been developed according to the manufacturing method and application. be. This material also includes binders and colorants used in the binder injection method.

For example, molding materials for 3D printers using the hot-melt lamination method (Patent Document 1), thermoplastic resins used in additive manufacturing technology, which are low-odor, less deformable, and capable of molding molded products with excellent transparency and surface treatability. A filament comprising an inner layer and an outer layer in the cross section of the filament, wherein the difference in melt flow rate of the resin composition constituting each layer is 10 (g / 10 min) or less (Patent Document 2) and the like.

On the other hand, the "manufacturing method" of elemental technology is roughly classified into seven methods by ASTM. A method in which a liquid binder is sprayed onto the powder bed and selectively solidified;2. 3. A method of selectively melting and bonding by controlling the position of heat generation by concentrating a beam or the like while supplying materials; 4. A method in which a fluid material is extruded from a nozzle and deposited while being solidified (typically the FDM method); 5. A method in which droplets of material are ejected, selectively deposited and solidified (typically an inkjet method); 5. A method of selectively melting and bonding the powder-covered region by thermal energy (typically a laser sintering method). 7. A method of adhering sheet materials such as paper, resin, and metal foil; There is a method (stereolithography method) in which a liquid photocurable resin stored in a tank is selectively cured by photopolymerization.

3D printers that are currently widespread for home use employ the FDM (Fused Deposition Modeling) method. The FDM method (Fused Deposition Modeling), as the name suggests, is a method in which resin is melted with heat and layered in the Z-axis direction for modeling. US Stratasys has a patent right for this technology (Patent Document 3), and when the validity of the right expires in 2009, many manufacturers will enter the market and general users will be able to easily obtain it. Printers were introduced to the market.

Furthermore, in 2014, the basic patent (3D Systems, Inc.) related to the above-mentioned laser sintering method expired. The laser sintering method consists of a thin layer forming process in which the powder is spread into a thin layer, and a laser beam is irradiated to the formed thin layer in a shape corresponding to the cross-sectional shape of the object to be molded, and the powder is bonded to the cross section. It is a method of manufacturing by sequentially repeating the shape forming process, and is suitable for precision molding as compared with other molding methods, and has the advantage of not requiring a holding member.

This sintering method using a laser beam is characterized by the fact that it can be used with many kinds of materials, and metals such as titanium, copper, and nickel can be used in addition to resins such as nylon. In addition, in the FDM method, a holding member is required to prevent the modeled object from collapsing during molding, but in the sintering method, the modeled object does not sink after hardening, so the holding member is not required as described above. However, there is also the problem that the device is slightly higher than the FDM type 3D printer because it uses laser light.

JP 2016-60147 A JP 2017-65111 A U.S. Pat. No. 5,121,329

The subject of the present invention is basically related to manufacturing techniques employing FDM and inkjet methods, and a method for creating a three-dimensional object with a desired shape, especially a three-dimensional object that does not require a support base. The object of the present invention is to provide a manufacturing method and an apparatus for use in the method.

In the FDM and inkjet methods mentioned in the section on the classification of 3D printer manufacturing methods, molding begins with placing the modeling material for the 3D printer on the substrate. At this time, each portion of the modeling material must maintain continuity (integrity) with other modeling portions or cannot be formed without support from the base.

For example, consider a modeled object such as a chain in which a plurality of rings are connected to each other. Each ring that constitutes the chain is not physically connected to other rings, and there are no protrusions other than the rings (for example, a support member from the base; in conventional injection molding, it can also be called a runner portion), etc. The proviso is that each ring is formed through an annulus of one or more other rings.

Such a chain cannot be directly manufactured by applying the conventional manufacturing method of a 3D printer as it is. Step by step, the previously formed ring is secured to some holding member and the next ring is formed through the previously formed ring while supporting the next ring by a substrate or another holding member. A repetitive method is required.

The present invention proposes a method of applying 3D printer technology without using the above-mentioned base or holding member by forming a three-dimensional object (for example, each ring) as if it were floating in the air. It is intended to

The present invention inserts a print head for printing a modeling material into a medium that is temporarily fluidized by heat or mechanical action from a gel state, and heats or operates the print head to produce a print head immediately adjacent to the print head. The medium is liquefied, the modeling material is ejected from the nozzles of the print head, and after the ejection, the liquefied medium returns to a gel state to create a desired three-dimensional object. In other words, the medium is in the same state as a normal 3D printer's modeling space while the modeling material is ejected, and after ejection, the surroundings of the modeling material gel and become a mold when the modeling material solidifies. is.

Examples of specific media include agar gel that is fluidized by heating and gelled by cooling, liquid paraffin that is gelled with polyethylene in an amount equivalent to 5 to 10%, and a medium that is fluidized by mechanical action. A physical gel obtained by dispersing a clay mineral having a particle diameter of 10 to 100 nm in a volume fraction of 0.0001 to 0.1 in water having a salt concentration of 0.0001 to 1 [M] is preferable. A physical gel is characterized by having so-called thixotropy.

Further, the clay mineral is preferably one or more selected from saponite, hectorite, and stevensite. This is because it is a highly safe substance that is suitable for expression and control of thixotropy and is also used in cosmetics as a viscosity modifier or dispersant.

When layered silicate minerals such as clay minerals are dispersed in water, the layers are negatively charged and the edges of the layers are positively charged to form an electrostatic bond to form a card house structure. The force that forms this structure acts as a resistance, resulting in elasticity and physical gelation. On the other hand, when a water-soluble metal salt is added to an aqueous gel composition formed from an aqueous dispersion of layered silicate minerals, a uniform card house structure is not formed, aggregation and precipitation occur, and no gel is formed. It turns into a sol. Therefore, in the present invention, the requirement for the physical gel is that the salt concentration be within a predetermined range.

Further, the three-dimensional object manufacturing apparatus of the present invention has a print head for printing a modeling material and a medium that is temporarily fluidized from a gel state by heat or mechanical action, and the print head is heated or It is characterized by liquefying the medium in the vicinity of the print head by operating it, ejecting the modeling material from the nozzles of the print head, and giving the desired shape by returning the liquefied medium to a gel state after ejection. and

The method for creating a three-dimensional object of the present invention and the manufacturing apparatus used therefor do not require a holder for a molded product, a support base, and the like, and can expand the scope of application of conventional 3D printer technology. Conventional molding methods such as FDM and inkjet are based on the premise that they are placed on a substrate. was able to be given.

In other words, three-dimensional objects can be molded even if they are not in contact with others. By applying the present invention, it is possible to mold only the target object.

FIG. 1 shows, as the medium of the present invention, sodium chloride concentration [M] and (y-axis) shear modulus ( Pa). In the figure, SA indicates saponite, HE indicates hectorite, and ST indicates stevensite (the same applies hereinafter). FIG. 2 shows, as the medium of the present invention, sodium chloride concentration [M] and (y-axis) shear modulus ( Pa). FIG. 3 shows, as the medium of the present invention, sodium chloride concentration [M] and (y-axis) shear modulus ( Pa). FIG. 4 is a photograph showing the results of molding a modeling material (araldite) using the medium of the present invention (physical gel containing saponite) (Example 1). FIG. 5 is a photograph showing the results of an attempt to mold by inserting the print head portion without heating using the medium as agar (Comparative Example 1). FIG. 6 shows the results of molding using a molding material (thermoplastic resin) while heating the print head using Hicol Gel (registered trademark) as a medium (Example 2). It is a photograph.

The method for creating a three-dimensional object according to the present invention includes inserting a print head for printing a modeling material into a medium that is temporarily fluidized from a gel state by thermal or mechanical action, and heating or operating the print head portion. The medium around the print head is liquefied by squeezing, the modeling material is ejected from the nozzles of the print head, and after ejection, the liquefied medium returns to a gel state to give the desired shape. do.

The medium of the present invention is normally in a gel state at room temperature, but is temporarily fluidized when heat or force is applied. As a result, the modeling material is ejected into the liquid, so printing is performed in the same way as a normal 3D printer. Even if the modeling material is in a liquid state for a while after being ejected and is then solidified (cross-linked) by photo-crosslinking or the like, the medium surrounding the modeling material will gel after printing. shape will be given. Therefore, the medium can also serve as a template.

As such a medium, the following three types are conceivable.

One example is agar, which is fluidized by heating and gelled by cooling. When using agar gel as a medium, the print head on the 3D printer must be of a type that generates heat. This is because if the print head is not moved before it is fluidized, the agar gel may crack and the modeling material may flow into the cracks, making it impossible to give the desired shape.

When an agar gel is used as a medium, the agar can be dissolved in hot water at a concentration of about 0.6 to 1.6% by weight and gelled by cooling. As is well known, agar gel does not melt unless the temperature is about 85° C. or higher, so the temperature of the print head section is also heated to a temperature higher than that. A build material is jetted into the heated and fluidized medium by the printhead assembly.

The second is to use a physical gel in which clay minerals are dispersed. In this case, it is preferable to use a clay mineral with a particle size of 10 to 100 nm dispersed in water with a salt concentration of 0.0001 to 1 [M] at a volume fraction of 0.0001 to 0.1. . When the physical gel is used as a medium, the print head portion does not need to be heated, and the gel around the traveling direction of the head portion is reversibly liquefied simply by following the movement of the head portion.

Here, the salt concentration in the water in which the physical gel is dispersed is important. When layered silicate minerals such as clay minerals are dispersed in water, the layers are negatively charged and the edges of the layers are positively charged to form an electrostatic bond to form a card house structure. The force that forms this structure acts as a resistance, resulting in elasticity and physical gelation. On the other hand, when a water-soluble metal salt is added to an aqueous gel composition formed from an aqueous dispersion of layered silicate minerals, a uniform card house structure is not formed, aggregation and precipitation occur, and no gel is formed. It turns into a sol. Therefore, it was required that the salt concentration be within a predetermined range.

When the salt concentration is lower or higher than the above range, as shown in FIGS. 1 to 3, the shear elastic modulus after dispersion becomes low, that is, the physical gel has poor shape retention in the solid state. Become. In FIG. 1, saponite (SA), hectorite (HE) and stevensite (ST) as clay minerals are dispersed in water at a volume fraction of 0.001, and sodium chloride concentration (M: mol/L) is 0.001. 007 [M] to 0.1 [M], showing the shear modulus G (Pa) of the physical gel. The shear modulus is a physical property value representing the resistance to deformation due to shear force. Similarly, FIG. 2 shows the relationship between salt concentration and shear modulus when the volume fraction of each clay mineral is 0.005, and FIG. 3 shows the relationship when the volume fraction is 0.01.

Especially when the concentration (volume fraction) of the clay mineral is low (Fig. 1 or Fig. 2), there is a tendency for the shear modulus to drop sharply as the salt concentration increases. On the other hand, when the concentration of clay minerals is high (Fig. 3), even if the salt concentration is high, there is relatively little effect. This indicates that even if the clay mineral that should form the card house structure is lost due to agglomeration or the like due to the existence of the salt, the solution has a surplus capacity sufficient to make up for the lost amount.

For the original purpose, it is sufficient that the clay mineral exists in an amount sufficient to maintain the structure of the physical gel, and it is not necessary to include it in a large amount. Because the physical gel also functions as a template, if it is included in a large amount, clay minerals may precipitate on the contact surface with the modeling material, which may interfere with the formation of a smooth surface of the modeled object. .

The physical gel can be obtained by dispersing clay minerals in water with adjusted salt concentration. This water is preferably pure water that has been desalted by ion exchange or the like, and specifically has an electric conductivity of about 0.05 to 1 mS/m. Of course, even when the electrical conductivity is lower or higher than the above-described electric conductivity, the shear modulus can be adjusted to a predetermined shear modulus by appropriately adjusting the salt concentration in the clay mineral and the salt concentration to be added separately.

A third example is liquid paraffin gelled with polyethylene in an amount corresponding to 5-10%. This type has the properties of both the agar gel and the physical gel, and when the print head is heated or moved, the gel temporarily becomes liquid within the range of its trajectory, and the print head moves. It reversibly changes from the liquid state back to the gel state when the printhead is stopped or the printhead is moved away. As a result, while the modeling material is ejected, it provides an environment similar to the ejection onto the substrate by a conventional 3D printer, and after ejection, the gelled medium around the modeling material acts as a template. be.

The present invention also relates to a three-dimensional object manufacturing apparatus used in the above method. The apparatus of the present invention is an apparatus for manufacturing a three-dimensional object of a desired shape from a building material, comprising a print head for printing the building material and a medium that is temporarily fluidized from a gel state by thermal or mechanical action. By heating or operating the print head, the medium in the immediate vicinity of the print head is liquefied, the modeling material is ejected from the nozzles of the print head, and after ejection, the liquefied medium returns to a gel state. It is characterized by imparting a desired shape. In other words, by applying the medium used in the present invention to a conventional 3D printer device, the environment that requires a substrate or the like used for conventional printing is completely changed, and a device that molds within the medium is provided. is.

Since the characteristics and particulars regarding the medium are as described above, only the print head section will be described here. The printhead assembly associated with the apparatus of the present invention operates after it has been inserted into the media. When a medium that is fluidized by heat is used, it is necessary to heat the inserted head portion. A conventional electric heating method may be used for heating, and if agar gel is used as a medium, it is inserted into the medium after being heated to a temperature of 85° C. or higher.

After that, the print head unit is moved within the medium to a predetermined position in a predetermined direction, and operates within a range for forming a desired shape while ejecting the modeling material from the head unit. After a certain amount of jetting is completed, the head unit temporarily moves out of the medium. The cooled medium gels while retaining the modeling material inside, and the modeling material is cured by ultraviolet irradiation or the like from the outside. Subsequently, the print head portion is again inserted into the media for the next shape formation, and the operation is repeated thereafter to finally form the desired shape.

When the medium is temporarily fluidized by mechanical action (for example, physical gel or liquid paraffin gel), the print head does not need to be heated, and the head moves. The only difference is that the gel is liquefied during the period, and other operations are the same as those described above.

In order to clarify the present invention more concretely, some examples are shown below.

(Example 1)
0.5 g of Sumecton SA (synthetic saponite; manufactured by Kunimine Industries Co., Ltd.) was dispersed in 5.5 g of ion-exchanged water (electrical conductivity: 0.0001 mS/m) to obtain the medium used in the present invention. The volume fraction is 0.036. Also, the salt concentration of the medium is 0.1 [M] or less.

As a modeling material, Araldite (epoxy-based adhesive: manufactured by Huntsman Japan Co., Ltd.) slightly mixed with water-based paint (yellow) is used, and this is used as a syringe (substitute for the print head part for the 3D printer of the present invention). I put it in

While inserting the tip of the syringe into the medium and injecting the modeling material, the object 1 was produced. As a result, articles of various shapes as shown in FIG.

(Comparative example 1)
Agar was used as a medium. In addition, the syringe was operated as in Example 1 without heating. As a result, since the agar was always in a gel state, the modeling material (the same material as in Example 1) was immediately crushed and penetrated into the cracks of the agar gel that had been destroyed by the action of the syringe before forming the shape. Alternatively, the desired shape could not be imparted due to oozing from the surface of the gel. The results are shown in FIG. FIG. 5 shows the state when viewed from above and the state when viewed from the side, and it can be seen from both states that the modeling material 2 is diffused. It should be noted that there is a possibility that molding can be performed as in Example 1 by heating the syringe.

(Example 2)
Hicol Gel (registered trademark manufactured by Kaneda Co., Ltd.; liquid paraffin gelled with polyethylene in an amount corresponding to 5 to 10%) was used as a medium, and a thermoplastic resin was used as a modeling material. The print head used at this time was heated to 150° C. or higher.

The results are shown in FIG. Since the head portion was heated, the result was that the thermoplastic resin was injected into it. The ring-shaped molded object 3 was created because the resin hardened quickly and the medium Hicol Gel (registered trademark) was liquefied by heating the head portion.

In this way, it was found that a desired shaped object can be obtained by forming a print head portion according to the medium, that is, by performing molding under conditions in which the medium is liquefied.

According to the present invention, by forming a three-dimensional object as if it were floating in the air, 3D printer technology can be applied without using a conventionally required base or holding member.

1 modeled object 2 modeled material 3 modeled object

Claims (1)

In a medium that is temporarily fluidized from a gel state by thermal or mechanical action,
Insert the print head that prints the build material,
liquefying the medium proximate the printhead by heating or operating the printhead;
The molding material is ejected from the nozzle of the print head,
A method for creating a three-dimensional object in which a desired shape is imparted by returning the liquefied medium to a gel state after ejection,
The medium is a physical gel obtained by dispersing a clay mineral with a particle size of 10 to 100 nm in a volume fraction of 0.0001 to 0.1 in water with a salt concentration of 0.0001 to 1 [M],
The clay mineral is at least one selected from saponite, hectorite, and stevensite.
A method of creating a three-dimensional object, characterized by:

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