JP2003001368A - Additive manufacturing method and additive manufacturing product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, concerning a lamination-shaping where a three-dimensional shaped article can be obtained by laminating a plurality of cured layers, a method for stably obtaining a lamination-shaped article that is excellent in the stability of shape and dimension, that has a smooth surface and an appropriate strength, and that is suitable for the use for a mold, etc., by repeatedly conducting two processes: a process where a thin powder layer is formed by spraying powder and a process where a cured layer of a two-dimensional pattern is formed by irradiating the powder layer with a laser beam. SOLUTION: Artificial ceramic sand consisting of spherical particles coated with a thermosetting resin component is used as a powdery shaping material.

Description

Detailed Description of the Invention

The present invention can be obtained by a layered molding method in which sand is used as a molding material and a thin layer of sand binding-cured by the heat of a laser beam is laminated and integrated to obtain a three-dimensional modeled object. It relates to an additive manufacturing product.

[0002]

2. Description of the Related Art In recent years, automobiles, aircraft, buildings, home appliances,
A method of designing and designing products and parts in various industrial fields such as toys and daily necessities on a computer such as CAD, CAM, CAE has become widespread. Then, as a latest means for producing a physical model that is a concrete representation of a three-dimensional model designed on such a computer, the additive manufacturing method has appeared.

In this additive manufacturing method, data of each cross-sectional pattern when a design model is sliced in parallel into a number of layers having a thickness of several tens to several hundreds μm on a computer is created, and this data is used as a controller of an additive manufacturing apparatus. Then, by irradiating the modeling material with a laser beam along the cross-sectional pattern of each layer, the sliced multiple layers are sequentially laminated one by one from the bottom layer, and finally the actual model corresponding to the design model. It is also referred to as a stereolithography method for forming a pattern by optical means using a laser beam, but it is roughly classified into a solution molding method and a powder molding method depending on the molding material used. .

The above-mentioned solution modeling method uses a solution of a photocurable resin such as an ultraviolet curable resin as a modeling material, and the resin component is cured by photoreaction with a laser beam to obtain a resin model. On the other hand, the powder molding method uses solid powder such as sand, metal powder, and resin powder as a molding material, and the powder particles themselves are sintered by the heat of the laser beam or melted through a mixed binder component. A molding die used for actual product manufacturing, not only as an actual model for shape confirmation, but also as a casting mold or resin molding die, etc. It is also expected as a method of making frames.

[0005] However, the method of producing a mold by additive manufacturing using sand is less costly than the conventional method of producing a sand mold for casting from a wooden mold of a product form because a wooden mold is not required. This is a sand mold for casting various hollow articles that handle fluids, especially because it can be done in a very short time without any effort and even if it has a very complicated shape, it can be formed as an integral body if there are continuous parts. It is suitable for the production of molds, etc., and it becomes possible to form a mold with an integrated core.

[0006]

However, in the layered molding of the powder molding method, heat is applied to the particle surface of resin-coated sand for casting generally used as a molding material, that is, silica sand, zircon sand, chromite sand, etc. When mold sand coated with a curable resin component is used, distortion occurs due to thermal expansion during modeling and post-cure (heating treatment) to accelerate hardening after modeling, and dimensional accuracy deteriorates. As a result, the layered product has a low density, a rough surface, and weak strength.In addition, it hinders the layer formation due to the powder spraying in the recoater and causes streaky scratches on the powder layer surface. However, there is a problem in that it causes the deterioration of the molding quality. On the other hand, resin coated sand for exclusive use of additive manufacturing has also appeared, but it is expensive and the distortion due to thermal expansion cannot be eliminated even with this, and the larger the model, the larger the distortion, especially the dimensional error. It is difficult to apply it to the production of a mold, especially a core, which is a fatal defect, and the surface property of the molded product is insufficient, so that when it is used as a mold, there is a problem that a rough and rough casting surface is obtained.

In view of the above-mentioned circumstances, the present invention uses powder-molding additive manufacturing using a resin coated sand as a molding material to provide excellent shape and dimensional stability, a smooth surface, and an appropriate strength. An object of the present invention is to provide means for surely obtaining a layered product suitable for use as a mold or the like.

[0008]

In order to achieve the above object, a layered manufacturing method according to claim 1 of the present invention comprises a step of spraying powder to form a thin powder layer, and the powder layer. In the layered manufacturing method, in which a plurality of hardened layers are laminated to obtain a three-dimensional modeled object by repeating the step of irradiating a laser beam on the substrate to form a hardened layer having a desired two-dimensional pattern, and thermosetting as the powder. It is characterized by using artificial ceramic sand consisting of spherical particles coated with a resinous resin component.

That is, in the layered manufacturing method of the above-mentioned claim 1, since the resin coated sand used as a molding material is composed of spherical particles and has good flowability and filling property, the resin coated sand smoothly flows out from the slit-shaped outlet of the recoater to form a molding. Evenly distributed over the entire surface, the resulting powder layer is in a uniform and densely packed state, and because the composition is also homogeneous with artificial ceramic sand, it is possible during laser beam irradiation or post cure. The resulting laminate-molded article is excellent in morphological and dimensional stability, has a smooth surface, and has appropriate strength.

According to a second aspect of the present invention, in the additive manufacturing method according to the first aspect, the artificial ceramic sand has a particle size of 75-75.
The particle size distribution has a peak in the range of 150 μm. In this case, in the layered manufacturing method using sand as a molding material, the thickness of one layer of the powder layer is generally set to about 200 μm, so that the sand particles have an appropriate size with respect to the thickness of the powder layer. This makes it possible to easily form a powder layer having a uniform thickness by spraying.

According to a third aspect of the invention, the first or second aspect of the invention is provided.
In the layered manufacturing method, the coating amount of the thermosetting resin component is in the range of 2 to 6% by weight with respect to the sand particles. In this case, the binding force between the sand particles due to the irradiation heat of the laser beam can be sufficiently secured, and the gas generation due to the curing reaction of the thermosetting resin component is suppressed, and the reduction of the laser beam transmittance due to this gas is prevented. To be done.

According to a fourth aspect of the present invention, in the layered manufacturing method according to any one of the first to third aspects, the artificial ceramic sand contains alumina and silica as main components.
In this case, since the artificial ceramic sand has a low expansion property,
The volume variation due to the laser beam irradiation at the time of additive manufacturing and the heat at the time of post cure is small, and the stability of the shape and dimensions of the obtained additive manufactured product is further improved.

According to a fifth aspect of the invention, in the layered manufacturing method of the fourth aspect, the artificial ceramic sand has a mullite crystal structure. Therefore, irradiation with a laser beam during layered manufacturing or heat during post-curing is performed. There is almost no volume fluctuation, and the morphological and dimensional stability of the obtained layered product is extremely high.

According to the sixth aspect of the present invention, in the layered manufacturing method according to any of the first to fifth aspects, since the sticking point of the artificial ceramic sand is 80 to 100 ° C., the laser beam at the time of layered manufacturing. By irradiating, the powder layer in the irradiated area is surely bound and hardened.

According to a seventh aspect of the present invention, in the layered manufacturing method according to any of the first to sixth aspects, the transverse rupture strength of the artificial ceramic sand is 100 to 170 kg / cm ² . In this case, the obtained laminate-molded product has an appropriate binding strength between the sand grains, and therefore, when used as a mold (sand mold), for example, while having sufficient strength against the pouring pressure, when taking out the cast product after casting The template can be easily decomposed.

According to an eighth aspect of the present invention, in the additive manufacturing method according to any one of the first to seventh aspects, the spherical particles of the artificial ceramic sand are granulated with a spray drier of ceramic material. In this case, since the particles of the artificial ceramic sand are substantially spherical and have a narrow particle size distribution width and uniform size, the powder layer formed by being sprayed by the recoater is more excellent due to its excellent fluidity and filling property. It will be uniform and the resulting additive laminate will be homogeneous throughout and have a smoother surface.

According to a ninth aspect of the present invention, in the layered manufacturing method according to any one of the first to eighth aspects, the thermosetting resin component is composed of a phenolic resin and a curing agent therefor. By irradiating the laser beam, the particles of the artificial ceramic sand are surely bound to each other.

According to the tenth aspect of the invention, in the layered manufacturing method according to the ninth aspect, the thermosetting resin component is composed of a novolac type phenol resin and hexamethylenetetramine. By the irradiation, the particles of the artificial ceramic sand are bound to each other more securely.

Since the additive manufacturing product according to the invention of claim 11 is obtained by the additive manufacturing method according to any one of claims 1 to 10, a smooth surface excellent in morphology and dimensional stability is obtained. Prepare

According to a twelfth aspect of the present invention, the laminate-molded article according to the eleventh aspect constitutes a casting main mold or core. In this case, since the main mold and the core are excellent in morphology and dimensional stability and have a smooth surface, the castings obtained by using them have high dimensional and dimensional accuracy and a smooth casting surface. Become.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The layered manufacturing method of the present invention is, as described above, a powder molding method, that is, a step of spraying powder to form a thin powder layer, and applying a laser beam to this powder layer. By repeating the step of irradiating and forming a hardened layer having a desired two-dimensional pattern, a large number of hardened layers are laminated to obtain a three-dimensional shaped article, and a thermosetting resin as powder of the shaping material. It is characterized by using an artificial ceramic sand consisting of spherical particles coated with a component.

This artificial ceramic sand belongs to the resin coated sand which is a mold sand for casting, but heats the surface of particles of natural sand such as silica sand, zircon sand and chromite sand like general resin coated sand. Not coated with curable resin component, but mixed with several kinds of powders of inorganic components such as inorganic oxides in the required ratio, granulate this mixture and fire at high temperature to make ceramic sand, and its particle surface Is coated with a thermosetting resin component. Therefore, in the present invention, as the artificial ceramic sand, spherical sand particles are used.

In order to manufacture a layered product, first, data of each cross-sectional pattern when a design model is sliced in parallel into multiple layers having a thickness of about 150 to 250 μm on a computer is created, and this data is stored in the layered product. Input to the controller and automatically perform additive manufacturing by powder molding method.
FIG. 1 and FIG. 2 are schematic vertical cross-sectional side views showing an example of a layered modeling apparatus by a powder modeling method.

In the layered molding, as shown in FIG. 1, a base plate 3 is placed on an elevating table 2 arranged in a box-shaped molding frame 1, and the artificial ceramic sand 5 is moved by horizontally moving a recoater 4. The parallel slice is placed on the base plate 3 with a thickness corresponding to one layer, and the surface of the powder layer 50 is irradiated with the laser beam 6 along the sectional pattern of the lowermost layer P ₁ . As a result, the thermosetting resin component coating the sand particles is melted by the heat of the laser beam 6 and undergoes a curing reaction, and the adjacent sand particles are bound together through the cured resin, and the entire irradiation area is integrated. Two-dimensional pattern binding hardened layer 5
1 will be formed. Then lowers the lifting platform 2 by the thickness of the one layer, new artificial ceramic sand 5 placed at a thickness corresponding to one layer said similarly binder corresponding to the second layer P ₂ by irradiating a laser beam 6 A hardened layer 51 is formed, and thereafter, in the same manner, the elevating table 2 is sequentially lowered by one layer to repeatedly supply the sand 5 and irradiate the laser beam 6 to finally perform the parallel slicing as shown in FIG. All layers P _{1 to} P _n are laminated and integrated.

When the additive manufacturing is completed in this way, the molding frame 1
The pace plate 3 is locked by the stopper 1a protruding inside, and the modeling frame 1 is removed from the elevating table 2 and the uncured sand 5 is removed to take out the layered product M formed. Since the obtained layered product M leaves a certain amount of unreacted portion in the thermosetting resin component binding the sand particles, it is usually subjected to heat treatment for a predetermined time in a heating furnace or the like as post cure. , Completely cure the resin component. It should be noted that the recoater 4 receives the sand 5 supplied from the material supply device 7 arranged above at both ends of its moving stroke and moves horizontally while letting the sand 5 flow out from the slit-shaped opening 4a at the lower end. Horizontal movement of one powder layer 50
To form. Reference numeral 60 is a laser oscillator such as a carbon dioxide laser, and 61 is a scanner for controlling the irradiation direction of the laser beam 6.

In the layered manufacturing method of the present invention, the artificial ceramic sand 5 is used as the powder of the molding material as described above.
Since this sand 5 is composed of spherical particles, it has good flowability and filling properties, and it smoothly flows out from the slit-shaped outlet 4a of the recoater 4 and is evenly distributed over the entire modeling surface, so that the powder layer 50 formed is uniform. Since the particles are densely packed and the artificial ceramic sand 5 is homogeneous in composition and has a low thermal expansion property, each binding hardening layer 51 precisely corresponds to each cross-sectional pattern of the parallel slice of the design model. It will be what you did. In addition, since the thermal expansion of the layered product M is small even during post-cure, the obtained modeled product has excellent morphological and dimensional stability, and has a smooth surface and appropriate strength.

The artificial ceramic sand consisting of such spherical particles is not particularly limited, but in order to make the particles spherical and having a narrow particle size distribution, a mud mixture prepared by adding water to the raw material powder mixture and kneading it is recommended. It is preferable that the particles are blown into hot air with a spray dryer to be granulated, and the granules are baked at a high temperature in a rotary kiln and separated by sieving or air sieving. The electron micrograph of FIG. 3 shows an artificial ceramic sand made of such spherical particles (S manufactured by Tochu Co., Ltd., which will be described later).
L1450-4) is shown, and it can be seen that this sand is composed of spherical particles having very uniform particle size. In contrast,
Since conventional resin-coated sand commercially available for additive manufacturing is made of natural silica sand, it is composed of irregular and angular particles as shown in the electron micrograph of FIG.

As the artificial ceramic sand used in the present invention, one having a particle size distribution having a peak in a particle size range of 75 to 150 μm is suitable. That is, since the thickness of one layer of the powder layer is generally set to about 200 μm in the layered manufacturing of the powder molding method as described above, if the particle size is too large, the powder having a uniform thickness can be dispersed by the recoater. In addition to the inability to form a layer, coarse particles are apt to be caught by the moving recoater to cause streak-like scratches on the surface of the powder layer, which deteriorates the molding accuracy. On the other hand, if the particle size is too small, the binding force between the particles due to laser beam irradiation becomes excessive, and the obtained layered product becomes unnecessarily hard,
In addition to hindering post-processing such as punching and cutting, disassembly after casting becomes difficult, especially when used as a casting mold or core.

The composition of the artificial ceramic sand is not particularly limited, but those containing alumina and silica as the main components are preferable, and particularly mullite crystals (3Al ₂ O ₃ .2Si).
Those having a structure of O ₂ ) are recommended. This is because the artificial ceramic sand mainly composed of alumina and silica has a low thermal expansion property, and particularly the mullite crystal structure has almost no volume change due to heat, so that laser beam irradiation during post-manufacturing or post-curing is performed. This is because the volume variation due to heat is small, and the stability of the shape and dimensions of the obtained layered product is further improved.

The thermosetting resin component with which the particle surface of the artificial ceramic sand is coated is not particularly limited as long as it causes a curing reaction by the irradiation heat of the laser beam at the time of additive manufacturing, but the curing From the viewpoints of rapidness and certainty of reaction and material cost, those composed of a phenolic resin and its curing agent (crosslinking agent) are preferable, and those composed of a novolac type phenolic resin and hexamethylenetetramine of a curing agent are particularly preferable. Recommended.

In order to coat the surface of the particles of artificial ceramic sand with the above-mentioned thermosetting resin component, for example, a mixer and a resin (thermoplastic resin such as the above-mentioned phenolic resin) of the main component are heated under heating. By mixing the resin component in a molten state to coat the surface of the sand particles, a solution of a curing agent (an aqueous solution of hexamethylenetetramine) is added and kneaded, and if necessary, the particles are bound to each other. Lubricant (release agent) such as calcium stearate to prevent
May be added and kneaded.

The coating amount of the thermosetting resin component is usually in the range of 1 to 10% by weight with respect to the artificial ceramic sand, but the range of 2 to 6% by weight is particularly preferable. If the coating amount is too small, the binding strength between the sand particles due to the curing reaction will be insufficient. On the other hand, if the coating amount is too large, the amount of gas generated due to the curing reaction will increase, which will deteriorate the laser beam transmittance and reduce the heat input, resulting in the binding force between sand particles and the binding between the upper and lower layers. The adhesion force becomes insufficient and the molding accuracy also decreases, and the obtained molded article is fragile, easily causes delamination, and has poor dimensional accuracy. In general, the modeling chamber of the modeling apparatus is provided with a suction device for removing the generated gas. However, if the suction is excessively increased, the scattering of sand from the recoater will be disturbed by the influence of the air flow.

The amount of the curing agent used with respect to the resin component of the main component in the thermosetting resin component varies depending on the type of the resin component. It is preferable to add methylenetetramine in a proportion of about 5 to 20% by weight. The above-mentioned lubricant such as calcium stearate is added to the resin component of the main agent in an amount of 0.
About 05 to 1% by weight may be blended.

In this way, the artificial ceramic sand coated with the thermosetting resin component has a fusion point in the range of 80 to 100 ° C. in order to more surely bind the sand particles to each other by the irradiation of the laser beam during the additive manufacturing. Is desirable. That is, when this fusion point is too low, when forming a two-dimensional pattern binder hardened layer by laser beam irradiation,
Curing progresses beyond the peripheral edge of the pattern, and even lower areas of the layer to be molded that should be originally uncured deteriorates the modeling accuracy, and the uncured sand is in a slightly solidified state. It is difficult to separate and remove the uncured sand from the subsequent layered model, which is troublesome, and the thin parts and complicated parts of the model are easily broken during the separation. On the other hand, if the fusion point is too high, the binding force becomes insufficient, and the molded article becomes brittle and delamination easily occurs. The fusion point can be easily adjusted depending on the type of thermosetting resin component used and the compounding ratio of the curing agent.

Further, as such artificial ceramic sand, one having a bending strength of 100 to 170 kg / cm ² is suitable. That is, if the transverse rupture strength is too weak, when the obtained laminate-molded article is used as a mold, there is a risk that cracks, breakage, breakage, or the like may occur in a thin portion or a thin portion due to the pouring pressure during casting. On the contrary, if the transverse rupture strength is too strong, it becomes difficult to disassemble the cast product when it is used as the mold. The transverse rupture strength can also be easily adjusted by the type of thermosetting resin component used for coating the ceramic sand, the mixing ratio of the curing agent, the coating amount, and the like.

A suitable commercial product of artificial ceramic sand consisting of spherical particles coated with such a thermosetting resin component is, for example, Cerabead 60- # 1 manufactured by Naigai Ceramic Co., Ltd.
450 or SL1450-4 manufactured by Tochu Co., Ltd. (both two layers of mullite crystal structure ceramic sand particles are coated with novolac type phenol resin-hexamethylenetetramine).
Etc. By the way, the RCS heat-expansion thermal expansion coefficient (expansion coefficient when heated at 1000 ° C. for 300 seconds in an electric furnace) is a commercially available resin coating sand for casting (resin coating amount 1.0% by weight) using natural silica sand. ) Is 1.39%, whereas Cerabeads 60- # 1450 (resin coating amount 2.0% by weight) shows a remarkably small value of 0.02%.

FIG. 5 shows the particle size distribution of the resin-coated sand through a sieve. The solid line A is the artificial ceramic sand S described above.
L1450-4, the broken line B is a resin-coated sand for exclusive use of commercially available additive manufacturing (made by EOS of Germany ... natural silica sand is used), and the one-dot chain line C is the particle size distribution of a commercially available casting resin-coated sand for casting (domestic natural sand is used) Indicates. This Figure 5
As is clear from the above, the artificial ceramic sand used in the present invention has a narrow particle size distribution width and a high peak at the distribution center, as compared with commercially available resin molding sand for exclusive use of additive manufacturing and resin coated sand for casting. It can be seen that the fraction is small and the particles consist of very uniform size.

The additive manufacturing product obtained by the additive manufacturing method of the present invention is not limited in use, and can be used as a model for morphological confirmation in the same manner as the additive manufacturing product made of a resin obtained by a solution forming method. It is especially useful as a main mold and core for casting.

[0039]

EXAMPLES Examples and comparative examples of the additive manufacturing method according to the present invention will be described below. In these examples and comparative examples,
EOSINT-S700 (modeling size ... width 720m left and right) made by EOS in Germany
m, front and rear width 380 mm, height 400 mm, laser oscillator ... 2 carbon dioxide lasers, laser scanning speed 3 m / S
(Above) was used.

Example An upper and lower main mold for casting an intake surge tank of an automobile engine manifold (a width of the tank portion is about 200 mm, a length of a substantially V-shaped curved pipe portion extending from the center of the tank portion is about 30 mm). With respect to the core, data of each cross-sectional pattern was created when the model designed on the computer was sliced in parallel to have a thickness of 200 μm. Then, this data is input to the controller of the additive manufacturing apparatus, and the artificial ceramic sand SL1450-manufactured by Tochu Co.
4 (coating resin component: 4.5% by weight of novolac type phenolic resin, 0.5% of hexamethylenetetramine to sand)
% By weight, lubricant ... calcium stearate with respect to sand
Using 2% by weight, an adhesion point of 86 ° C., and a transverse rupture force of 145 Kg / cm), the thickness of the powder layer formed by one movement of the recoater was set to 200 μm, and the additive manufacturing was performed automatically. Then, when the heat treatment for 2 hours at 200 ° C. was performed in the heating furnace as post-cure on the obtained upper and lower main molds and the core-layered molded product, the form and the size of the product closely matched the design model. It was a layered product with a fine and smooth surface.

Next, a mold was produced by assembling the cores of the upper and lower molds of these laminated moldings and a core, and the molten aluminum alloy was poured into the mold to cast the cylinder head. An aluminum casting was obtained which did not occur and had a smooth casting surface and no defects. Since the core was decomposed into sand particles by applying vibration, it could be easily removed from the hollow portion of the cast product.

Comparative Example Laminated molding was carried out in the same manner as in the above Example except that the commercially available resin coated sand for exclusive use of additive manufacturing (the coating resin component and the lubricant were the same as those of the ceramic sand of Example) was used as the molding material. Post-cure was performed to obtain a laminate molding product of the upper and lower main molds and the core. These additive-molded products are distorted due to thermal expansion, and the maximum is +
A dimensional error of 3 mm was generated and a slight change in shape was observed, and the surface state was rougher than that of the example. Then, an attempt was made to assemble a mold by using the upper and lower molds and the core, but the size of the core board portion of the core was too large to fit into the core board receiving portion of the lower mold.

[0043]

According to the additive manufacturing method of the first aspect,
In additive manufacturing of the powder molding method, since artificial ceramic sand consisting of spherical particles coated with a thermosetting resin component is used as a molding material, a powder layer in which the entire molding surface is uniformly and densely packed with particles. In addition to being able to form, it is difficult to cause local deformation due to laser beam irradiation during additive manufacturing and post-cure heat after modeling, and the resulting additive-molded product has excellent morphological and dimensional stability, and a smooth surface. In addition to having the appropriate strength.

According to the second aspect of the present invention, in the above-mentioned additive manufacturing method, since the artificial ceramic sand having a specific particle size distribution is used, a powder layer having a more uniform thickness can be formed by spraying. The quality of the layered product is further improved.

According to the third aspect of the present invention, in the above-described layered manufacturing method, since the artificial ceramic sand having a coating amount of the thermosetting resin component within a specific range is used, the strength and size are excellent. A highly accurate layered product can be obtained.

According to the invention of claim 4, in the above additive manufacturing method, since the artificial ceramic sand having a specific composition is used, the volume variation due to the irradiation of the laser beam during additive manufacturing and the heat during post curing is small, The morphological and dimensional stability of the obtained layered product is further improved.

According to the fifth aspect of the present invention, since artificial ceramic sand having a specific crystal structure is used in the above-mentioned layered manufacturing method, a volume due to laser beam irradiation at the time of layered manufacturing or heat at the time of post cure is used. There is almost no fluctuation, and the morphological and dimensional stability of the obtained laminate-molded article becomes extremely high.

According to the invention of claim 6, in the above-mentioned additive manufacturing method, since the sticking point of the artificial ceramic sand is within a specific range, the powder layer is surely bound by the irradiation of the laser beam during additive manufacturing. Can be cured.

According to the invention of claim 7, in the above-mentioned layered manufacturing method, since the artificial ceramic sand obtained by the specific granulation method is used, it is formed by the excellent fluidity and filling property. The powder layer becomes more uniform, and a layered product having a uniform surface and a smoother surface is obtained.

According to the eighth aspect of the present invention, since artificial ceramic sand coated with a specific resin component is used in the above-mentioned layered manufacturing method, sand particles are surely formed by laser beam irradiation during layered manufacturing. Can be tied to.

According to the ninth aspect of the present invention, since the specific main component and the curing agent are used as the resin component, the particles of the artificial ceramic sand are more surely bound to each other by the irradiation of the laser beam during the layered manufacturing. be able to.

According to the tenth aspect of the present invention, in the above-mentioned additive manufacturing method, since the artificial ceramic sand having a specific transverse rupture strength is used, it has sufficient strength especially when used as a mold, and It is possible to obtain a mold in which the mold can be easily disassembled when the cast product is taken out after the casting.

According to the eleventh aspect of the present invention, there is provided a laminate-molded article made of a binder-cured cured resin-coated sand, which is excellent in morphology and dimensional stability and has a smooth surface.

According to the twelfth aspect of the invention, it is possible to obtain, as the above-mentioned layered product, a casting product which is a main mold or core for casting and has a smooth casting surface with high dimensional and shape accuracy. The possible ones are offered.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional side view showing an initial stage of a layered manufacturing method of the present invention.

FIG. 2 is a schematic vertical sectional side view showing a final stage of the additive manufacturing method.

FIG. 3 is an electron micrograph image of artificial ceramic sand used in the layered manufacturing method of the present invention.

FIG. 4 is an electron micrograph of a conventional resin coated sand for additive manufacturing.

FIG. 5 is a particle size distribution diagram of an artificial ceramic sand used in the layered manufacturing method of the present invention, and a conventional layered resin-coated sand and casting resin-coated sand.

[Explanation of symbols]

1 modeling frame 2 lifts 3 pace plates 4 recoaters 5 Artificial ceramic sand 50 powder layer 51 Binder hardened layer 6 laser beam M additive manufacturing

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22C 9/02 101 B22C 9/02 101E 103 103D 9/10 9/10 EJ // B23K 26/00 B23K 26/00 G B29C 67/00 B29C 67/00 B29K 101: 10 B29K 101: 10 103: 06 103: 06 F term (reference) 4E068 AA00 DB12 DB14 4E092 AA03 AA04 AA33 AA45 AA47 BA08 BA20 CA01 CA02 CA10 4E093 FC10 JA03 JA04 NB08 QA01 4F213 AA36 AA37 AB16 AB26 WA25 WB01 WL10 WL23 WL29 WL43 WL74 WL75 WL96 WW15 WW33

Claims (12)

[Claims] 1. A step of spraying powder to form a thin powder layer, and a step of irradiating the powder layer with a laser beam to carry out the required 2 steps.
In the layered modeling method for obtaining a three-dimensional model by laminating a plurality of cured layers by repeating the step of forming a cured layer having a three-dimensional pattern, spherical particles coated with a thermosetting resin component as the powder. An additive manufacturing method characterized by using an artificial ceramic sand consisting of. 2. The artificial ceramic sand has a particle size of 75 to 15
The additive manufacturing method according to claim 1, comprising a particle size distribution having a peak in the range of 0 μm. 3. The additive manufacturing method according to claim 1 or 2, wherein the coating amount of the thermosetting resin component is in the range of 2 to 6% by weight based on the sand particles. 4. The additive manufacturing method according to claim 1, wherein the artificial ceramic sand contains alumina and silica as main components. 5. The additive manufacturing method according to claim 4, wherein the artificial ceramic sand has a mullite crystal structure. 6. The artificial ceramic sand has a sticking point of 80 to 80.
It is 100 degreeC, The additive manufacturing method in any one of Claims 1-5. 7. The bending strength of the artificial ceramic sand is 100.
~ 170 kg / cm ²In any one of Claims 1-6 which is
The layered product described. 8. The additive manufacturing method according to claim 1, wherein the spherical particles of the artificial ceramic sand are formed by granulating mud support of a ceramic material with a spray dryer. 9. The additive manufacturing method according to claim 1, wherein the thermosetting resin component comprises a phenolic resin and a curing agent therefor. 10. The additive manufacturing method according to claim 9, wherein the thermosetting resin component comprises a novolac-type phenol resin and hexamethylenetetramine. 11. A layered product obtained by the layered manufacturing method according to any one of claims 1 to 10. 12. The layered product according to claim 11, which constitutes a main mold or core for casting.