JP2001047188A - Resin-coated powder for additive manufacturing - Google Patents

Abstract

(57) Abstract: Provided is a resin-coated powder for lamination molding, such as a resin-coated sand, which has further improved light or heat absorption. A resin-coated powder for layered molding is formed by applying light or heat to a spray layer to form a hardened layer, and by laminating a large number of hardened layers to form a three-dimensional model, a spray layer. Is used for the formation of In addition to the resin, the resin-coated powder contains an absorbing material (eg, graphite powder) having good light or heat absorbability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin-coated powder for additive manufacturing.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 9-136139 discloses a lamination molding method. This method uses a resin-coated sand formed by coating a resin on sand particles, by spraying the resin-coated sand to form a thin scatter layer, and by irradiating the scatter layer with light or heat. This is a technique in which a plurality of cured layers are sequentially laminated in the thickness direction by repeating an irradiation step of forming a cured layer by thermal curing, a spraying step, and an irradiation step, thereby forming a three-dimensional model.

[0003] This resin-coated sand is formed by coating a thermosetting resin with sand particles. In the additive manufacturing method, the portion of the scattered layer to which light or heat is applied,
Portions that form a cured layer but are not exposed to light or heat remain uncured layers. After modeling, the uncured layer is disintegrated and removed from the cured layer.

[0004]

The above-mentioned resin-coated sand preferably has a high light or heat absorbability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a resin-coated powder such as resin-coated sand and the like, which further enhances light or heat absorption. Make it an issue.

[0006]

Means for Solving the Problems The resin-coated granules for additive manufacturing according to the present invention form a hardened layer by applying light or heat to a spray layer, and form a three-dimensional shaped object by stacking a number of hardened layers. A resin-coated powder used for forming a scatter layer in a layered molding method for modeling, the resin-coated powder,
In addition to the resin, a light- or heat-absorbing material having good absorbability is compounded.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the additive manufacturing method, any of visible light and invisible light can be adopted as light for curing a scatter layer. In particular, light having a wavelength in the infrared region can be employed. The infrared region is a near-infrared region (wavelength region: 0.83 μm to 2 μm), a mid-infrared region having wavelengths of far infrared light and near infrared light (wavelength region: 2 μm).
４4 μm).

Accordingly, the light for curing the spray layer is
Infrared lamp light and laser beam can be adopted. As a laser beam, Nd-YA having a wavelength in the near infrared region
A G (yttrium aluminum garnet) laser beam (wavelength: 1.06 μm) can be employed.

As the heat, heat generated by absorbing the irradiated infrared rays can be employed.

[0010] A typical powdery material is refractory particles. Examples of the material of the refractory particles include oxides and carbides, and for example, refractory particles such as silica, zirconia, mullite, and alumina can be employed.
Specifically, silica sand, zircon sand, olivine sand and the like can be employed. In some cases, the material of the granular material may be metal.

The average particle size of the granular material varies depending on the accuracy, cost and the like required for the three-dimensional molded article, but is 5 to 300 μm in the form of no resin coating, and 20 to 20 μm.
0 μm and 50 to 120 μm can be employed. In particular, the average particle size of the powder is preferably about 100 μm.
However, it is not limited to these.

For example, the lower limit of the average particle size of the powder can be 6 μm, 10 μm, 30 μm or the like, and the upper limit may be 250 μm, 200 μm, 150 μm.
m etc. can be adopted.

The shape of the granular material may be a round shape, a polygonal shape, a horn shape, etc., and a spherical shape and a true spherical shape are particularly preferable. However, it is not limited to these.

The resin constituting the resin-coated powder has a property of curing when light or heat is applied. A typical resin is a thermosetting resin. Typical thermosetting resins include phenolic resins and modified resins thereof.

The resin-coated powder contains, in addition to the resin, an absorbing material having good light or heat absorbability.
Absorbing materials generally have better light or heat absorption than resins. In order to suppress uneven distribution of the absorbing substance, it is preferable that the absorbing substance is uniformly mixed in the resin. As the absorbing material, a carbon-based powder can be used. As typical carbon-based powders, graphite powder and amorphous carbon powder can be employed.

Further, as the above-mentioned absorbing substance, a substance which improves the fluidity of the resin-coated powder when it is blended with the resin-coated powder, is preferable. Those having properties that can be used are also preferable. In general, carbon-based powders such as the above-mentioned graphite powder and amorphous carbon powder easily contribute to improvement in fluidity and disintegration.

The above-mentioned absorbing substance such as graphite powder may be unevenly distributed when directly mixed with a powder (sand particle) alone.
Therefore, it is preferable to use a mixture in which the absorbing material such as graphite powder and the resin are preliminarily mixed, and knead the mixture with the granules using a mixer or the like. Alternatively, a method may be employed in which a dispersion water in which an absorbing substance is dispersed in an aqueous solution in which hexamine is dissolved is used, and the powder and the resin are kneaded with a mixer or the like, and the dispersion water is added.

The compounding amount of the absorbing material includes the type and cost of the absorbing material, the absorption required for the resin-coated powder, the fluidity required for the resin-coated powder, the disintegration of the cured layer, and the like. It can be appropriately selected according to the factors. As the compounding amount of the absorbing substance, for example, 0.0
5 to 2.0 parts by weight, particularly 0.1 to 1.0 part by weight, further 0.2 to 0.8 part by weight can be blended. In consideration of the above circumstances, the lower limit of the amount of the absorbing substance may be 0.07 parts by weight, 0.1 parts by weight, 0.3 parts by weight, or the like. As the value, 2.0 parts by weight, 1.5 parts by weight, 1.3 parts by weight and the like can be adopted.

Here, "1 part by weight of the absorbing material" means that 1.0 g of graphite powder was blended with the resin, assuming that the total weight of the resin was 100 g, and 101 g as a whole. Becomes

Since silica, mullite, zircon sand, and olivine sand, which are typical examples of the above-mentioned powders and granules, have high infrared transmittance, they can be irradiated with a laser beam having a wavelength in the infrared or infrared region from an infrared lamp. It is difficult to obtain satisfactory heating efficiency. However, if an absorbing substance such as graphite powder is blended together with the resin, they have good absorbency, so that the heating efficiency is improved. Further, the flowability of the resin-coated powder can be improved, and the disintegration of the cured layer during the disintegration treatment is also improved.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings together with test examples.

As described above, the layered molding method is a method in which light or heat is applied to the scatter layer to form a cured layer, and a number of cured layers are laminated to form a three-dimensional molded article.

The resin-coated sand, which is the resin-coated powder according to the present embodiment, is used for forming a scatter layer. The resin-coated sand is composed of sand particles as powder, resin coated with the sand particles, and graphite powder as a carbon-based powder mixed in the resin. The sand particles are silica, are spherical, and have high sphericity. In the state where the resin is not coated, the average particle size of the sand particles is around 100 μm.

The resin is a phenol resin which is a thermosetting resin. The fusion temperature is 70-120 ° C.

In producing the resin-coated sand, a method is used in which a mixture of graphite powder, which is a carbon-based powder, and a resin is previously mixed, and the mixture is kneaded with a granular material.

In the spraying step, using the above-mentioned resin-coated sand, the resin-coated sand is horizontally and two-dimensionally sprayed to form a thin spraying layer (thickness: about 200 μm). Thereafter, the scattered layer is irradiated with infrared rays to thermally cure the resin of the resin-coated sand, and the adjacent resin-coated sands are bonded to each other, thereby forming a cured layer. Hereinafter, by repeatedly performing the above-described spraying step and the irradiation step in order, a large number of cured layers are stacked in the thickness direction to form a three-dimensional modeled object. This shaped article is intended to be used as a sand mold for casting, in which a high-temperature molten metal is cast.

The inventor of the present invention appropriately changed the ratio of the graphite powder to the resin to obtain infrared absorbing properties, the strength of the molded product as a laminate of the cured layer, and the strength of the molded product as a laminate of the cured layer after casting. A test was conducted for disintegration.

The infrared absorption is expressed by (actual heating energy) /
(Actual heating energy) ratio%. The strength of the molded article as the hardened layer was measured by the JIS normal temperature bending strength method.
The disintegration of the shaped article was tested using a test piece having an aluminum core.

FIG. 1 shows the test results. The horizontal axis in FIG. 1 shows the amount of graphite powder added. The left vertical axis in FIG. 1 shows the infrared absorptivity, and the right vertical axis shows the strength of the molded article and the disintegration of the molded article after casting. In FIG. 1, a characteristic line A indicates the infrared absorptivity, a characteristic line B indicates the strength of the molded article, and a characteristic line C indicates the disintegration of the molded article after casting.

As shown by the characteristic line A, as the proportion of the graphite powder increases, the absorptivity of infrared rays gradually increases. As shown by the characteristic line B, as the proportion of the graphite powder increases, the sintering strength of the molded article gradually increases.
(0.7 parts by weight), the firing strength gradually decreases.
As shown by the characteristic line C, if the ratio of the graphite powder increases,
The disintegration of the molded article after casting gradually increases.

In the case of an application intended to improve infrared absorption and disintegration, the proportion of the graphite powder may be increased based on the above test results. In addition, in the case of an application that is intended not only to improve the infrared absorption property and the disintegration property, but also to secure the strength of the molded article, excessive blending of the graphite powder is not preferable.

That is, the strength required for the shaped article differs depending on the actual use of the shaped article. Depending on the type of the modeled object, it may be sufficient if it is about 2 [kgf / cm ² ] or more. When the molded article is used as a casting sand mold into which molten metal is cast, the strength is preferably 4 [kgf / cm ² ] or more, particularly 6 [kgf / cm ² ] or more. Is preferred. Therefore, in consideration of ensuring the strength of the molded article, the amount of graphite powder to be added is preferably about 0.2 to 0.9 parts by weight, particularly 0.4 to 0 parts by weight based on the test results shown in FIG. About 0.7 parts by weight is preferred.

(Application Example) An application example will be described. This application example is for forming a sand mold for casting.

As shown in FIG. 2, the molding apparatus 5 of the present embodiment
A frame 6 having a molding space 6a inside, and an arrow Y inside the frame 6
An elevating body 7 having an elevating board 7a provided to be able to elevate in the Y1, Y2 directions, a drive source 8 for driving the elevating body 7 to elevate and lower, and moving in the horizontal direction, that is, the directions of arrows X1 and X2 along the elevating board 7a. There is provided a dispersing means 9 movably provided, and an irradiation source device 10 movably provided above the frame 6.

The drive source 8 can be formed by a motor mechanism or a hydraulic cylinder mechanism. The dispersing means 9 includes a container 90 containing the resin-coated sand, and a cut-out roller 9 rotatably provided at a discharge port 91 at the front end opening of the container 90.
With 2. With the rotation of the cut-out roller 92, the container 9
The resin-coated sand in 0 is cut out by a fixed amount and discharged from the discharge port 91. Normally, spraying means 9
Is retracted from the modeling frame 6, but moves upward along the modeling frame 6 during spraying.

The irradiation source device 10 heats the scattering layer 100 with infrared rays, and includes a plurality of infrared lamps 10a for irradiating infrared rays, and a reflector 10c having a concave surface 10b disposed above the infrared lamp 10a. It has.

The reflector 10c directs the infrared light emitted upward from the infrared lamp 10a downward, that is, the scattering layer 1
It reflects toward 00 and can be formed of an aluminum-based material having a high reflectance. Since infrared rays are easily absorbed by the resin containing graphite, the resin can be thermoset effectively. In a normal state, the irradiation source device 10 is retracted from the modeling frame 6, but at the time of irradiation, the irradiation source device 10 moves above the scatter layer 100 as shown in FIG.

In the spraying step, while the irradiation source device 10 and the mask 200 are retracted from above the frame 6, the spraying means 9 is moved in the direction of arrow X 1 while rotating the cutting roller 92, whereby the container 90 is rotated. The resin-coated sand is discharged from the discharge port 91 to form a scatter layer 100 having a uniform thickness. Since the resin-coated sand contains graphite powder having lubricity, the dischargeability from the discharge port 91 of the container 90 is improved.

In the irradiation step, a mask 200 having a predetermined pattern is arranged above the frame 6 with the spraying means 9 retracted from above the frame 6. In order to ensure irradiation accuracy, it is preferable that the mask 200 be close to the scatter layer 100. Furthermore, in the irradiation step, the irradiation source device 10 is moved and arranged above the mask 200, and the infrared rays from the irradiation source device 10 are irradiated on the scatter layer 100 through the mask to heat the scatter layer 100.

The resin-coated sand in the portion of the scatter layer 100 which has been irradiated due to the light-shielding property of the mask 200 remains uncured, forming an uncured layer 120. However, since the resin of the coated sand in the portion irradiated with the infrared rays is thermally cured, the adjacent resin coated sands are bonded to each other to form the cured layer 110.

Hereinafter, the above-mentioned spraying layer and irradiation step are repeated in order, and a large number of cured layers 110 are laminated to form a laminate. In the laminate taken out of the frame 6, the surplus uncured layer 120 is removed, and a sand mold for casting, which is a three-dimensional object, is taken out.

The graphite powder contained in the resin-coated sand forming the cured layer 110 is in an appropriate amount (0.1 to 1.0% with respect to the resin). Therefore, the sand mold, which is a three-dimensional molded object, has a high sintering strength and can suppress damage to the sand mold during transportation, handling, and the like.

When removing the extra uncured layer 120,
The resin-coated sand constituting the uncured layer 120 contains graphite powder, and the graphite powder can also function as a solid lubricant, so that the fluidity is good and the work of removing the uncured layer 120 from the cured layer 110 is easy. Becomes

After the sand mold is formed as described above, a high-temperature molten metal is poured into the molding cavity of the casting sand mold and solidified to form a casting. Thereafter, the entire casting sand mold is mechanically collapsed and the casting is taken out. Since the graphite powder of the resin-coated sand burns due to the high heat of the cast metal melt, the collapse of the sand mold after casting is improved, and the casting is easily taken out.

In addition, the present invention is not limited to the embodiment described above and shown in the drawings, but can be implemented with appropriate modifications as needed.

(Supplementary Note) The following technical idea can be understood from the above description. A method for producing a resin-coated powder for additive manufacturing, comprising: using a mixture in which an absorbent such as graphite powder and a resin are mixed in advance, and kneading the mixture with a powder (sand particles). This is advantageous for suppressing uneven distribution of an absorbing substance such as graphite powder. Production of a resin-coated powder for additive manufacturing, characterized in that water is added when a powder (sand particle) and a resin are kneaded using an absorbent such as graphite powder and water containing hexamine. Method. This is advantageous for suppressing uneven distribution of an absorbing substance such as graphite powder. A spraying step of forming a spraying layer by spraying the resin-coated powder-coated granules according to the claims, and curing by applying light or heat to the sprayed layer. A lamination molding method in which a plurality of cured layers are laminated to form a three-dimensional molded product (eg, a sand mold for casting) by repeating the irradiation step of forming a layer, the spraying step, and the irradiation step a plurality of times in this order. The resin-coated granular material for lamination molding according to any one of claims, which is excellent in light or heat absorption, strength of the molded article, and disintegration property of the molded article after casting. In each of the claims, the resin-coated powder for additive manufacturing is characterized in that the resin covering the powder contains the absorbent material.

[0047]

According to the present invention, it is possible to provide a resin-coated granular material for lamination molding such as a resin-coated sand and the like, which has further enhanced light or heat absorption.

Further, when the absorbing substance is a carbon-based powder such as graphite powder, the absorption of light or heat can be adjusted by adjusting the amount of the carbon-based powder. Further, the strength of the three-dimensional structure can be adjusted, and the disintegration of the three-dimensional structure after use can be adjusted.

[Brief description of the drawings]

FIG. 1 is a graph showing test results.

FIG. 2 is a configuration diagram showing an application example.

[Explanation of symbols]

In the figure, 5 is a shaping device, 6 is a frame, 7 is an elevating body, and 100 is a scatter layer.

Claims (3)

[Claims] The present invention is used for forming a scattered layer in a lamination molding method in which a hardened layer is formed by applying light or heat to a scatter layer, and a plurality of the hardened layers are laminated to form a three-dimensional molded article. Characterized in that, in addition to the resin, the resin-coated powder and granules are mixed with an absorbing material having good light or heat absorption properties. Granules. 2. The resin-coated powder for additive manufacturing according to claim 1, wherein the absorbing substance is a carbon-based powder. 3. The resin-coated granular material for lamination molding according to claim 1, wherein the absorbent is added in an amount of 0.1 to 1.0 part by weight based on the resin.