KR20210120370A - A method for cooling cores of 3D printing using molding sand material - Google Patents

Abstract

The objective of the present invention is to provide a 3D printing method of a cooling channel inside a mold using a foundry sand material that realizes a cooling core with a complex shape and dramatically shortens the manufacturing time by manufacturing the cooling core with a binder jetting process. The 3D printing method of a cooling core using a foundry sand material according to the present invention comprises: (a) a step for applying a foundry sand material to a bed; (b) a step for spraying a liquid adhesive on the foundry sand material; and (c) a step for manufacturing a cooling core, wherein the cooling core is manufactured by a binder jetting process.

Description

3D printing method of cooling cores using molding sand material {A method for cooling cores of 3D printing using molding sand material}

The present invention relates to a 3D printing method of a cooling channel inside a mold using a molding sand material, and more particularly, a 3D printing method of a cooling channel inside a mold using a molding sand material for manufacturing a cooling core by an adhesive jetting (BJ) method is about

In the mold industry, which produces a large amount of goods by repeating pouring and hardening of resin into a mold, cycle time is important.

Cycle time is the time it takes to produce one item, and since the next item must be hardened quickly, it is very important to cool the mold quickly. For this purpose, the technique of forming cooling channels in the mold is widely used.

The closer the cooling channel is to the surface of the mold defining the shape of the article, the better the cooling effect is, so the shape-adaptive cooling channel according to the shape of the article is also used.

However, in the case of a complex shape, it is difficult to form a shape-adaptive cooling channel inside the mold by a traditional processing method.

The 3D printer can output an article having a hollow structure of a complex shape, so it is possible to output a mold having a shape-adaptive cooling channel to the 3D printer.

However, the mold output by the 3D printer has pores therein, so there is a problem in that the surface peeling phenomenon appears when a large amount of articles are molded into the mold.

(Patent Document 1) Patent Publication No. 10-2019-0055035 (2019.05.22.)

(Patent Document 2) Registered Patent Publication No. 10-1784371 (2017.09.27.)

An object of the present invention to solve the above problems is to implement a cooling core of a complex shape and dramatically shorten the manufacturing time by manufacturing the cooling core in the adhesive jetting (BJ: Binder Jetting) method. To provide a 3D printing method of a cooling channel.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

The configuration of the present invention for achieving the above object is a 3D printing method of a cooling core using a molding sand material, comprising the steps of: (a) applying the molding sand material to a bed; (b) spraying a liquid adhesive on the molding sand material; and (c) manufacturing the cooling core, wherein the cooling core is manufactured by a binder jetting (BJ) method. .

In an embodiment of the present invention, the molding sand material may be characterized in that it is composed of aluminum oxide and a thermosetting resin.

In an embodiment of the present invention, the thermosetting resin may be coated to surround the aluminum oxide.

In an embodiment of the present invention, in the molding sand material, the aluminum oxide is composed of 95% to 99% of the molding sand material, and the thermosetting resin is composed of 1% to 5% of the molding sand material, characterized in that can do.

In an embodiment of the present invention, in step (b), the liquid adhesive may be sprayed from at least one nozzle.

In an embodiment of the present invention, the step (c) comprises: (c1) stopping the operation of the at least one nozzle to stop spraying the liquid adhesive; and (c2) checking whether the cooling core is completed, and in the step (c2), the cooling core is completed when it is completed.

In an embodiment of the present invention, the step (c) may further include: (c3) returning to the step (a) when the cooling core is incomplete in the step (c2). can

According to the effect of the present invention according to the configuration as described above, it is possible to realize a cooling core having a complicated shape and significantly shorten the manufacturing time by manufacturing the cooling core in a binder jetting (BJ) method.

The effects of the present invention are not limited to the above effects, but it should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a flowchart illustrating a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention.
2 (a) and (b) are views showing the molding sand material of the 3D printing method of the cooling core using the molding sand material according to an embodiment of the present invention.
3 is a perspective view illustrating a cooling core and a support structure manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention.
4 is a perspective view illustrating a cooling core manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be “connected (connected, contacted, coupled)” with another part, it is not only “directly connected” but also “indirectly connected” with another member interposed therebetween. "Including cases where In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention. 2 (a) and (b) are views showing the molding sand material of the 3D printing method of the cooling core using the molding sand material according to an embodiment of the present invention.

1, in the 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention, (a) applying the molding sand material to the bed (S100), (b) liquid adhesive on the molding sand material and (S200) and (c) manufacturing the cooling core 100 (S300), and the cooling core 100 is manufactured by an adhesive jetting (BJ) method.

The step (a) is a step of applying the molding sand material to the bed of the 3D printer, wherein the 3D printer manufactures the cooling core 300 in a binder jetting (BJ) method.

In step (b), the liquid adhesive is sprayed from at least one nozzle. Specifically, at least one nozzle is a jet nozzle capable of jetting a liquid adhesive, and a plurality of nozzles may be formed. This configuration has the advantage of being able to manufacture a finished product faster than the conventional 3D printing method.

The at least one nozzle sprays a liquid adhesive to the molding sand material in a predetermined shape, and thus a part of the cooling core 100 is primarily formed while the liquid adhesive is bonded to the molding sand material.

Step (c) includes (c1) stopping the operation of at least one nozzle to stop spraying of the liquid adhesive, and (c2) checking whether the cooling core 100 is completed.

In addition, in the step (c2), when the cooling core 100 is completed, it ends.

Meanwhile, step (c) further includes (c3) returning to step (a) when the cooling core 100 is not completed in step (c2).

Accordingly, when returning to step (a), the liquid adhesive is adhered to the bed and the molding sand material is applied again, and then the steps (b) and (c) are performed.

The aforementioned molding sand material may be formed of particles as shown in (a) and (b) of FIG. 2 . In particular, the casting sand material is composed of aluminum oxide (Al ₂ O ₃ SiO ₂ ) and a thermosetting resin.

The thermosetting resin is coated to surround the aluminum oxide.

Specifically, in the molding sand material, aluminum oxide is composed of 95% to 99% of the molding sand material, and the thermosetting resin is composed of 1% to 5% of the molding sand material. If necessary, the content ratio may be reduced and diphenylmethylenediamine may be additionally added, and diphenylmethylenediamine (C ₁₃ H ₁₄ N ₂ ) may be composed of 0.1% to 0.5% of the molding sand material.

In addition, it is preferable that the density of the molding sand material is 2.7g/cm ³ (25°C), and the melting point of the molding sand material is 1825°C.

Fig. 2 (a) is an image of the molding sand material enlarged in units of 100 µm, and Fig. 2 (b) is an image of the molding sand material enlarged in units of 10 µm.

Unit Value standard D10

μm 62.7

TAU-18171 D50 85.9 D90 113.0 Mean size 86.6 Apparent density g/cm ³ 1.64 ASTM B212 Angle of repose ° Flow time for 50g s ASTM B212

[Table 1] specifies specific information on the material of the casting sand.

3 is a perspective view illustrating a cooling core and a support structure manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention. 4 is a perspective view illustrating a cooling core manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention.

A cooling core and a support structure as shown in FIG. 3 are manufactured by the 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention.

Referring to FIGS. 3 and 4 , the cooling core 100 is implemented according to a predetermined shape of the 3D printer, and is manufactured in a core shape in the present invention, but is not limited thereto, and can be implemented in any other shape. .

The support structure 10 includes a support 11 and a support plate 12 .

The support 11 is a component to be coupled to the inside of the casting mold, and is manufactured together with the cooling core 100 by the 3D printing method of the cooling core using the molding sand material of the present invention.

The support 11 may have a hexahedral shape, but any shape may be used as long as it can be combined with the casting mold.

The support plate 12 may have an annular rotating body shape, and is manufactured together with the cooling core 100 by the 3D printing method of the cooling core using the molding sand material of the present invention.

The support plate 12 serves to connect the support 11 and the cooling core 100 .

The 3D printing method of the cooling core using the molding sand material described above can easily manufacture a complex shape to be implemented, and can be manufactured more quickly and easily than the conventional 3D printing method.

The support structure 10 is included in the cooling core 100 .

Referring to FIG. 4 , the cooling core 100 and the support structure 10 integrally formed are inserted into the casting mold and only the support structure 10 is melted by heating after the casting process to finally form the support structure 10 . Only the removed cooling core 100 remains.

Hereinafter, a method of forming a cooling channel inside a casting mold to which a cooling core manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention is applied will be described.

The method for forming a cooling channel inside the casting mold includes the steps of (a) manufacturing a cooling core, (b) positioning the cooling core inside the mold, (c) casting molten metal into the mold, (d) Cooling the molten metal and (e) removing the cooling core by pneumatic or hydraulic pressure to form a cooling channel inside the casting mold.

The step (a) includes (a1) applying a molding sand material to the bed, (a2) providing a liquid adhesive or laser to the molding sand material, and (a3) manufacturing a cooling core.

The mold includes an upper mold, a lower mold and molten metal.

Next, step (b) includes (b1) separating the upper and lower molds, (b2) positioning a cooling core inside the lower mold, and (b3) combining the upper and lower molds.

Next, the step (c) is, (c1) preparing the molten metal, (c2) connecting the injection tube to the lower mold to communicate with the inside of the mold, (c3) injecting the molten metal into the injection tube, and (c4) cooling the molten metal injected into the mold.

In the step (c3), the molten metal fills the space formed by the upper mold, the lower mold, and the cooling core along the injection pipe.

Then, when the step (c4) proceeds, the molten metal filling the space formed by the upper mold, the lower mold, and the cooling core 100 is cooled to become a casting mold, and a cooling channel is formed inside the casting mold.

Next, in step (d), the molten metal is cooled to wait until the molten metal is completely combined with the lower mold and solidified.

Additionally, after step (d), the method may further include cutting at least a portion of the support structure 10 connected to the cooling core 100 .

Specifically, when the molten metal is solidified, the cooling core 100 and the support 12 connected to the cooling core 100 are cut as shown in FIG. 3 . At this time, a plurality of holes are formed in the portion where the support 12 and the cooling core 100 are connected, and all of the plurality of holes except for the injection pipe inlet 30 and the injection pipe outlet 40 shown in FIG. 4 are cooled. It is blocked with a material similar to that of the core 100 .

Accordingly, the cooling core 100 has only the injection pipe inlet 30 and the injection pipe outlet 40 .

Finally, step (e) includes (e1) connecting a removal unit (not shown) to communicate with the end of the cooling core 100, (e2) providing pneumatic or hydraulic pressure through the removal unit, (e3) The cooling core 100 is discharged to the outside of the casting mold by pneumatic or hydraulic pressure to be removed, and (e4) the cooling channel 100 is formed in the casting mold.

In the step (e1), the ends of the cooling core 100 mean the injection pipe inlet 30 and the injection pipe outlet 40 .

When step (e1), step (e2), step (e3), and step (e4) are performed, a casting mold is finally manufactured.

Hereinafter, a casting mold to which a shape-adaptive cooling channel using a cooling core manufactured by a 3D printing method of a cooling core using a molding sand material according to an embodiment of the present invention is applied will be described.

In the casting mold to which the shape adaptive cooling channel is applied according to an embodiment of the present invention, a cooling core 100 is removed by placing a 3D printed cooling core 100 inside the mold and then the cooling core 100 is removed to form a cooling channel. In the casting mold to which the formed shape-adaptive cooling channel is applied, the cooling core 100 and the mold are included, and all of the above-described contents are included.

In more detail, the cooling core 100 includes at least one support plate 11 positioned on the side of the cooling core 100 and at least one supporting plate 11 connecting the side of the cooling core 100 with the at least one support plate 11 . It includes a support 12, and at least one support plate 11 is fixedly inserted into the at least one lower mold groove.

The cooling core 100 may have a shape similar to that of a spring, and since it is manufactured by 3D printing, a more complex shape may be implemented. That is, the cooling core 100 shown in FIGS. 2 and 3 is only illustrated by way of example and is not limited thereto.

The mold includes an upper mold, a lower mold and molten metal.

The image may have a hexahedral shape. A groove may be formed in the upper part of the upper die in a cylindrical shape. A first protrusion protruding downward and a first concave portion recessed upward are formed in the lower vertex portion of the upper die.

The lower form is combined with the upper form.

In addition, the lower mold may have a hollow shape with an empty interior to accommodate the cooling core 100 .

At least one lower mold groove recessed toward the outer surface of the lower mold is formed on the inner surface of the lower mold.

The molten metal is injected into the lower mold where the cooling core is located and solidified. Specifically, the molten metal is melted and injected into the space formed by the cooling core 100 located inside the upper, lower, and lower molds 220 through the injection pipe in a liquid state, cooled and changed to a solid state.

Thereafter, the cooling core 100 is discharged to the outside of the upper and lower molds and removed, and accordingly, a casting mold in which a cooling channel is formed is finally manufactured.

The cooling channel is formed inside the molten metal while the cooling core 100 is removed.

Specifically, the cooling channel is formed inside the molten metal along the inner surface of the molten metal. In particular, the cooling channels are formed to be spaced apart from the inner surface of the molten metal by the same distance.

The finished product is manufactured through injection molding and metal molding in the inner space formed between the upper and lower molds. can be implemented

The existing mold manufactured by the gun drill method according to the prior art is composed of an existing mold body and a cooling channel formed inside the existing mold body, but the cooling channel is manufactured only in a linear form.

On the other hand, the casting mold manufactured by the method of forming a cooling channel inside the casting mold to which the cooling core is applied, manufactured by the 3D printing method of the cooling core using the molding sand material according to an embodiment of the present invention, is complex using the 3D printing method. The shape of the cooling core and cooling channel is not limited thereto.

Even if the outer surface of the casting mold body is curved and has a curved surface, according to the present invention, the cooling core 100 and the cooling channel can be formed correspondingly to be spaced apart while maintaining the same distance from the outer surface of the casting mold body. .

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

10: support structure
11: support
12: support plate
30: inlet of injection tube
40: injection pipe outlet
100: cooling core

Claims (7)

In the 3D printing method of a cooling core using a molding sand material,
(a) applying the molding sand material to the bed;
(b) spraying a liquid adhesive on the molding sand material; and
(c) manufacturing the cooling core;
The cooling core is a 3D printing method of a cooling core using a molding sand material, characterized in that manufactured by an adhesive jetting (BJ: Binder Jetting) method.
According to claim 1,
The molding sand material is a 3D printing method of a cooling core using a molding sand material, characterized in that it consists of aluminum oxide and a thermosetting resin.
3. The method of claim 2,
The 3D printing method of the cooling core using the molding sand material, characterized in that the thermosetting resin is coated to surround the aluminum oxide.
3. The method of claim 2,
In the molding sand material,
The aluminum oxide is composed of 95% to 99% of the casting sand material,
The 3D printing method of the cooling core using the molding sand material, characterized in that the thermosetting resin is composed of 1% to 5% of the molding sand material.
According to claim 1,
Step (b) is,
The 3D printing method of the cooling core using the molding sand material, characterized in that the liquid adhesive is sprayed from at least one nozzle.
6. The method of claim 5,
The step (c) is,
(c1) stopping the operation of the at least one nozzle to stop spraying the liquid adhesive; and
(c2) checking whether the cooling core is completed;
In the step (c2), the 3D printing method of the cooling core using the molding sand material, characterized in that the end when the cooling core is completed.
7. The method of claim 6,
The step (c) is,
When the cooling core is incomplete in step (c2),
(c3) returning to step (a); 3D printing method of a cooling core using a molding sand material, characterized in that it further comprises.

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