KR101667302B1 - Mold with Air Coolant for Preventing Shrinkage in Full Mold Casting - Google Patents

Abstract

The present invention relates to a mold to prevent shrinkage in a full mold casting using an air coolant to improve a quality of a casting, and prevents defects in the casting by reducing a difference in cooling velocity between a thick part and a thin part; accelerating the cooling velocity of a thick part of casting in the full mold casting. To achieve this purpose, the present invention comprises: a mold provided for a full mold casting; a coolant pipe inserted to a thick part of the mold; and a coolant supply apparatus to continuously supply the air coolant to the coolant pipe. The coolant pipe is inserted to the thick part of the mold with both ends protruded thereon to be connected to the coolant supply apparatus on one end to continuously receive the air coolant and to discharge the supplied air coolant to the outside on the other end. Moreover, the coolant pipe inserted to the mold is able to be adjusted with a diameter in accordance with a thickness of the mold, and a heat radiation coating layer is formed on an inner circumference of the coolant pipe to increase an effect of heat radiation from the mold.

Description

Technical Field [0001] The present invention relates to a mold for air-

More particularly, the present invention relates to a mold for casting a full mold with a pneumatic refrigerant, and more particularly, to a mold for casting which is capable of accelerating the cooling speed of the thick portion of the casting and reducing the cooling rate difference between the thick portion and the thin portion, And to improve the quality of the casting.

Casting is one of the most fundamental techniques of metallurgy used by mankind and is used to produce large quantities of the same shape.

The casting method is to heat and dissolve scrap, pig iron, ferroalloy or ferrous metal raw materials in a furnace, pour it into a mold of sand or metal, and cool and solidify it.

In other words, when molten metal is injected into a mold made of a desired model, and the molten metal solidifies, it becomes the same metal object as the model.

The casting process consists of casting design, casting plan, modeling, melting and injection, and end-of-product finishing. The type used for casting is called "鑄 形" and the product made by casting is called 鑄 物.

Casting can be carried out by sand casting, shell-mold casting, eaporative pattern casting, plaster-mold casting, ceramic-mold casting, .

Vacuum casting to make gas pressure, Centrifugal casting to make pipes and cylinders with centrifugal force, Vacuum casting to vacuum mold the mold, Molten metal is injected into the machined mold, And die casting for obtaining castings.

In addition, there is a full mold casting in which a casting is formed by burying and pouring in a model mold made of expanded polystyrene, and a molten metal is introduced into a cavity formed by combustion / vaporization of expanded polystyrene as heat of a molten metal. Is called the lossless model casting method, the lost form, the EPC process, the FMC process, and so on.

The full-mold casting method can be defined as " a casting method for casting while replacing the casting mold and the molten casting in the casting mold ". The mold is called full mold casting because it is filled with models.

Such a full mold casting process can be a substitute for conventional casting molds because of its environment-friendly advantages, economical efficiency, and its ability to form a near net shape that is close to the final product, It is attracting attention as a method.

Fig. 1 is a view for explaining a general full mold casting method. In the full mold casting method, first, a mold 100 is formed which is molded into the same shape as a cast product to be manufactured using expanded polystyrene (EPS) or polymethyl methacrylate (PMMA) as a raw material such as styrofoam .

When the mold material 110 is coated on the surface of the mold 100 and then embedded in the unbonded sand (unbindered sand) 120 without the binder, and then the molten metal 130 is injected, The embedded mold 100 is vaporized by the heat of the molten metal 130 and discharged into the sand, and the molten metal injected into the molten metal 100 is cooled to obtain a desired casting.

In the general casting method, the part where the molten metal is filled is a cavity, and the pouring frame is composed of sand having a pointing force. However, in the full mold casting method, the part where the molten metal 130 is taken is composed of the mold 100 And is filled with a non-point-like shape (120) which can not form a mold around it.

Accordingly, the non-pointed mover 120 supporting the mold 100 has fluidity and has a characteristic of continuously moving until the vibration-filling type molding process is completed.

Due to this characteristic, a technique for installing a device for controlling the cooling rate of the casting or the like on a mold has not yet been implemented.

On the other hand, the molten metal injected from the full mold casting method dissolves, discharges and replaces the model using the thermal energy. Therefore, the temperature of the molten metal tip is lowered preferentially, and the molten metal is injected in a relatively laminar flow.

In the conventional cavity mold, the cooling rate and solidification shape of the melt depend on the shape of the casting. However, in the full mold casting method, the cooling rate and solidification shape of the melt are greatly influenced by the direction of the melt and the distance to the injection port. Particularly, when the full mold casting method is applied to a low melting point alloy such as an aluminum alloy, the influence is more remarkable.

FIG. 2 is a view showing casting defects due to internal shrinkage occurring in conventional thick portions.

Referring to the drawings, when the cooling rate of the molten metal is lowered in the full-mold casting operation, casting defects are caused by shrinkage of the casting surface and internal shrinkage. Such casting shrinkage is caused by thinning of the casting, Thicker than the thicker than the thicker portion appears more prominent.

Accordingly, in order to prevent the shrinkage of the casting surface and the shrinkage caused by the difference in the cooling speed due to the thickness variation of the casting, the casting block or the carbon block is used for the casting, The cooling rate of the surface is controlled, but the effect is not transmitted to the inner part of the product thicker than the thickness of product. In case of pouring work, the melt temperature of more than 1,400 degrees is compared with the product thickness (2mm ~ 400mm) The surface shrinkage and internal shrinkage can not be solved due to too heavy weight in the case of thickness), so that the productivity is reduced and the reliability of the product is lowered because the casting defect is not solved.

Korean Patent Publication No. 2004-0038333

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide a cooling pipe in a thick part of a casting and to prevent a casting defect by preventing the melting of a pipe by forcibly supplying an air- The present invention is directed to a mold for casting a full mold for shrinkage prevention using an air refrigerant.

In addition, a coating layer laminated with a heat radiation composition is formed on the inner edge of the cooling pipe to further improve the cooling efficiency, and the cooling rate between the thin portion and the thick portion can be uniformly controlled by controlling the composition ratio of the heat radiation composition according to the thickness difference of the thick portion The present invention is also directed to a mold for casting a mold for shrinkage prevention using a pneumatic refrigerant.

The present invention has the following features in order to achieve the above object.

The present invention relates to a mold for a full mold casting, A cooling pipe inserted into a thick portion of the mold; And a refrigerant supply device for continuously supplying the air refrigerant to the cooling pipe.

Here, the cooling pipe is inserted into the thick portion of the mold so as to protrude at both ends thereof. One end of the cooling pipe is connected to the refrigerant supply device to continuously receive the air refrigerant, and the other end thereof discharges the supplied air refrigerant to the outside .

Also, the diameter of the cooling pipe inserted into the mold is controlled according to the thickness of the mold, and a heat radiation coating layer is formed on the inner edge of the cooling pipe so as to increase heat radiation efficiency from the mold.

The heat dissipation coating layer may be formed of at least one selected from the group consisting of (a) graphite, (b) graphene, (c) epoxy resin binder and (d) silicon oxide, boron nitride, kaolin, aluminum hydroxide, bentonite, Mica, and magnesium aluminum silicate. ≪ Desc / Clms Page number 7 >

Preferably, the epoxy resin is a bisphenol-type epoxy resin or a novolak-type epoxy resin, and the heat radiation composition comprises 20 to 30 parts by weight of graphene, 300 to 500 parts by weight of binder, 100 to 500 parts by weight of heat- 200 parts by weight.

The heat radiation composition includes 20 parts by weight of graphene, 400 parts by weight of a bisphenol epoxy resin binder, and 150 parts by weight of magnesium aluminum silicate, based on 100 parts by weight of the graphite.

The cooling pipe is formed with a threaded cut portion and a heat dissipating pipe is coupled to an inner side of the cutout portion. The heat dissipating pipe includes a depressed portion having a certain accommodation space, and a depressed portion extending to the depressed portion, As shown in Fig.

And a protruding piece protruding outside the flange portion of the heat dissipating pipe is formed on the cutting groove and the receiving pocket formed on the upper or lower side of the cutting portion of the cooling pipe to position the heat dissipating pipe on the inner cut portion of the cooling pipe, The protrusions are inserted into the receiving pocket and coupled with each other as the protrusions are rotated through a predetermined angle.

According to the present invention, there is an effect that the cooling speed of the thick portion can be rapidly advanced through the cooling pipe arranged in the thick portion of the casting, thereby preventing casting defects.

In addition, cooling efficiency is further improved through the heat-radiating coating layer of the cooling pipe, and the cooling rate between the thin portion and the thick portion is controlled uniformly by controlling the composition ratio of the heat radiation composition according to the difference in casting thickness.

Fig. 1 is a view for explaining a general full mold casting method.
FIG. 2 is a view showing casting defects generated in a thick portion of a conventional casting. FIG.
3 is a view showing a state in which a cooling pipe according to the present invention is inserted into a mold.
4 is a view showing a combined state of a refrigerant supply apparatus according to an embodiment of the present invention.
5 is a sectional view taken along the line AA 'of FIG.
6 is a cross-sectional view taken along line BB 'of FIG.
7 is a B-B 'sectional view showing a cooling pipe according to another embodiment of the present invention.
8 is a view illustrating a process of installing a heat pipe according to another embodiment of the present invention.
FIG. 9 is a view showing a cooling pipe provided with a heat-radiating pipe according to FIG.
FIG. 10 is a view showing a process of fastening between a heat radiating pipe and a cooling pipe according to FIG.
FIG. 11 is a cross-sectional view of the heat dissipating pipe in a state where it is coupled to the cooling pipe according to FIG. 8. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the sake of convenience, the size, line thickness, and the like of the components shown in the drawings referenced in the description of the present invention may be exaggerated somewhat. The terms used in the description of the present invention are defined in consideration of the functions of the present invention, and thus may be changed depending on the user, the intention of the operator, customs, and the like. Therefore, the definition of this term should be based on the contents of this specification as a whole.

FIG. 3 is a view showing a state where a cooling pipe according to the present invention is inserted into a mold, FIG. 4 is a view showing a combined state of a refrigerant supply device according to an embodiment of the present invention, FIG. 5 is a cross- Sectional view.

Referring to the drawings, a full mold casting according to an embodiment of the present invention includes a mold 10, a cooling pipe 20 inserted into a thick portion H of the mold 10, A coolant supply device 30 for continuously supplying the air refrigerant to the mold 10, and a molding sand 60 surrounding the mold 10.

Here, the mold 10 is disposed to function as a cavity of a general mold due to the disappearance of the molten metal when the molten metal is injected, and the cooling pipe 20 is inserted into the mold 10 according to the present invention.

This cooling pipe 20 is determined depending on the shape of the mold 10 and the number of insertions and insertions is determined. The thickness of the cooling pipe 20 in the shape of the mold 10 is large, 20 are inserted.

Such a cooling pipe 20 does not deteriorate as the refrigerant is continuously supplied by the refrigerant supply device 30 during the injection of the molten metal. Even if the refrigerant is supplied, the pipe material 20 having a low heat resistance may be deteriorated. .

Accordingly, the material of the cooling pipe 20 according to the present invention includes carbon steel pipes for pipes, carbon steel pipes for pressure pipes (SPPS, STPG (mainly STPG 370)), carbon steel pipes for high pressure pipes (SPPH) (SPHT) or the like is preferable.

In addition, since the possibility of deterioration becomes lower as the thickness of the cooling pipe 20 becomes thicker, it is preferable to constitute the cooling pipe 20 of 5 mm or more.

The cooling pipe 20 is vertically inserted into the thick portions H of the thick both sides as the mold 10 is thicker than the intermediate portion as shown in Figs. 3 and 4, Both ends of the upper and lower sides of the mold 10 are protruded by a predetermined length.

The supply piping 40 and the discharge piping 50 are respectively connected to the protruded both side ends 21 and 22 of the cooling pipe 20 and the supply piping 40 can communicate with the refrigerant supply device 30 .

The coolant supply device 30 is provided to supply cool air to the supply pipe 40. The coolant supply device 30 may be configured to supply room temperature air or supply low temperature air of 0 to -20 DEG C .

The refrigerant transferred from the supply pipe 40 is heat-exchanged through the cooling pipe 20 and discharged through the discharge pipe 50 at a high temperature.

In the present invention, the refrigerant supply device 30 is configured to continuously supply the refrigerant. However, the refrigerant supply device 30 may be configured to have a circulation structure as required.

That is, the discharge piping 50 is connected to the refrigerant supply device 30 and is supplied to the supply pipe again after being reduced. In this case, a separate heat exchange module is installed in the refrigerant supply device 30, To the low temperature state and supply it to the supply pipe (40).

On the other hand, when the thick portion H and the thin portion T are clearly defined and the thickness of the thin portion T is relatively small as shown in FIG. 3 depending on the shape of the mold 10, The thickness of the thick portion H is smaller than that of the thick portion H and the thickness T of the thick portion H is larger than that of the thick portion H, The cooling pipe 20 is inserted into the thin-walled portion T as well.

At this time, in order to uniformize the relative cooling rate between the thick portion H having a thickness difference or between the thick portion H and the thin portion T, the diameter of the cooling pipe 20 is changed or the temperature or the amount of refrigerant .

When the diameter of the cooling pipe 20 is different, it is constituted in proportion to the relative thickness ratio between the thick portions H or the thick portion H and the thin portion T. When the temperature or the refrigerant amount of the refrigerant is different It is preferable to configure it in proportion to the square of the relative thickness ratio between the thick portion (H) or between the thick portion (H) and the thin portion (T).

When the cooling is completed after the molten metal is injected, the casting is completed in the form of the desired mold. The casting includes the cooling pipe 20.

Therefore, the end-side projecting portion of the cooling pipe 20 after completion of the casting can be kept cut or sealed with a coupling means such as a bolt, if necessary, only on the end opening portion.

In the case where the hole is formed in the casting when the cooling pipe 20 is formed, it is also possible to form the cooling pipe 20 at the hole machining position so that the cooling pipe 20 is removed by hole machining after completion of the casting, have.

When the cooling pipe 20 belongs to the main functional part of the casting, it is preferable to form the cooling pipe 20 at the hole processing position. If the cooling pipe 20 does not belong to the main function part, the diameter of the cooling pipe 20 is not large, The impact will be negligible and the post-treatment will be done by cutting the protruding end or sealing the opening.

In the present invention, a heat dissipation coating layer 23 is formed on the cooling pipe 20, and the heat dissipation coating layer 23 is preferably coated with the heat dissipation composition on the graphite or metal base.

(C) an epoxy resin binder; and (d) a binder selected from the group consisting of silicon oxide, boron nitride, kaolin, aluminum hydroxide, bentonite, talc, mica mica, and magnesium aluminum silicate. < Desc / Clms Page number 7 >

Generally, carbon materials such as carbon nanotubes, graphene, and diamond are known to have superior thermal conductivity and heat resistance, rather than graphite, but they are not suitable for use as the material of the cooling pipe 20 because they are expensive.

Accordingly, in the present invention, a heat-radiating composition containing graphite and graphene is used so as to have an excellent heat radiation effect while minimizing the amount of graphene having an excellent thermal conductivity. Since the graphene can deteriorate the resin used as a binder over time, it is important to use a suitable binder.

Examples of the epoxy resins include bisphenol-type epoxy resins and novolak-type epoxy resins. Representative examples of bisphenols that form the bisphenol-type epoxy resin include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A, Tetramethyl bisphenol F, tetramethyl bisphenol AD, tetramethyl bisphenol S, tetrabromobisphenol A, tetrachlorobisphenol A, tetrafluorobisphenol A, and the like. Examples of the novolak-type epoxy resin include phenol novolac resins, and novolak-type epoxy resins obtained by reacting a resole novolak resin with a haloepoxide.

The heat radiation composition preferably includes 20 to 30 parts by weight of graphene, 300 to 500 parts by weight of binder, and 100 to 200 parts by weight of heat-radiating powder, based on 100 parts by weight of the graphite. If the content of the graphite, graphene and heat-releasing powder is out of the above range, there is a fear that the heat radiation effect is lowered. If the content of the binder is out of the above range, coating on the cooling pipe 20 may not be smoothly performed .

In addition, the heat radiation composition may further include titanium oxide powder, carbon black powder and iron oxide powder as coloring pigments.

The heat radiation composition can be produced by a melt mixing method, a dry mixing method, or other general or publicly known methods. For example, in the melt mixing method, a binder selected from the group consisting of (a) graphite, (b) graphene, (c) epoxy resin and polyester resin, and (d) silicon oxide, boron heat-dissipating powders selected from the group consisting of aluminum nitride, kaolin, aluminum hydroxide, bentonite, talc, mica and magnesium aluminum silicate are dry-mixed using a mixer or the like and then melt-mixed with a kneader or an extruder , Cooling the mixed composition to solidify it, and finely grinding the mixture to a particle size of 10 to 200 mu m.

The heat radiation composition may be heated and softened or melted and then coated on the cooling pipe 20. The coating method is not particularly limited, and examples thereof include a flow-dipping method, an electrostatic-fluidizing method, an electrostatic spraying method, and a cascade method.

≪ Example 1 >

40 g of a bisphenol-type epoxy resin binder (EPOKUKDO YD-014) and 15 g of magnesium aluminum silicate were dry mixed with 10 g of graphite, 2 g of graphene (xg science, M15 grade), a high-speed mixer and melted and mixed by an extruder , Cooling it, and then finishing it to prepare a heat radiation composition.

After the prepared heat radiation composition was melted, it was coated on the inner edge of a cooling pipe (outer diameter: 50 mm, inner diameter: 30 mm) by spraying to a thickness of 20 to 30 탆. The coated cooling pipe 20 was mounted on the mold, and 10 minutes after the injection of the molten metal, the change in the discharge temperature of the air refrigerant transferred from the refrigerant supply device 30 was measured, and the results are shown in Table 1.

The refrigerant supply device 30 is a TOHIN air cooler that supplies cold air at a low temperature. The compressed air pressure is 0.7 MPa, the compressed air consumption is 390 L / min, and the discharge temperature is -20 ° C.

≪ Example 2 >

Except that 10 g of graphite, 2 g of graphene (xg science, M15 grade), 40 g of a bisphenol type epoxy resin binder (EPOKUKDO YD-014) and 15 g of magnesium aluminum silicate were used. . ≪ / RTI >

≪ Example 3 >

Except that 40 g of graphite, 2 g of graphene (xg science, M15 grade), 40 g of novolak type epoxy resin binder (EPICLON N-675) and 15 g of magnesium aluminum silicate were used. 1. ≪ / RTI >

<Example 4>

Except that 10 g of graphite, 2 g of graft (xg science, M15 grade), 40 g of a bisphenol type epoxy resin binder (EPOKUKDO YD-014) and 20 g of boron nitride were used. The same procedure was followed.

&Lt; Comparative Example 1 &

A change in the discharge temperature of the air refrigerant transferred from the refrigerant supply device 30 was measured after 10 minutes from the mounting of the cooling pipe 20 without coating the heat radiation composition on the mold, Respectively.

&Lt; Comparative Example 2 &

10 g of graphite, 1 g of graft (xg science, M15 grade), 40 g of a silicone resin binder (OE 6631 A) and 15 g of magnesium aluminum silicate were used to prepare the heat radiation composition .

&Lt; Comparative Example 3 &

Except that 10 g of graphite, 1 g of graft (xg science, M15 grade), 40 g of polycarbonate resin binder (INFINO SC-1190) and 15 g of magnesium aluminum silicate were used. The same procedure was followed.

Heat release value (℃) Coating property Example 1 72.5 Good Example 2 76.9 Good Example 3 74.3 Good Example 4 75.1 Good Comparative Example 1 55.5 - Comparative Example 2 - Bad Comparative Example 3 - Bad

It can be seen from Table 1 that the temperature of the cooling pipe 20 not coated with the heat radiation composition was 55.5 ° C, whereas Examples 1 to 4 showed a temperature higher than that of Comparative Example 1 by at least about 15 ° C.

On the other hand, in Comparative Examples 2 and 3 using a silicone resin and a polycarbonate resin as binders, it was confirmed that the coating was not properly performed.

FIG. 8 is a view showing a process of installing a heat pipe according to another embodiment of the present invention, FIG. 9 is a view showing a cooling pipe provided with a heat pipe according to FIG. 8, FIG. 11 is a cross-sectional view illustrating a state where the heat-radiating pipe is coupled to the cooling pipe according to FIG. 8. FIG.

Referring to the drawings, the cooling pipe 20 according to the present embodiment is provided with a heat dissipating tube 70 formed with a threaded cut portion and coupled to the cut portion.

The heat dissipation pipe 70 includes a depression 71 located inside the incision of the cooling pipe 20 and having a predetermined accommodation space and a recessed portion 71 extending from the depression 71 to be in contact with the inner wall surface of the cooling pipe 20 And a flange portion 72 fixed thereto.

The accommodation space of the depression 71 may be formed in a triangular shape in cross section as shown in the drawing, and other shapes may be used.

As the heat is further transferred into the cooling pipe 20 as much as the recessed space of the depression 71, the heat exchange contact area is further increased and the heat exchange efficiency can be improved by increasing the heat exchange contact area.

A cutout groove 20a and a projecting piece 70a protruding outside the flange portion 72 of the heat dissipating pipe 70 and the cutout groove 20a formed in the upper or lower side of the cutting portion of the cooling pipe 20 .

The heat dissipation pipe 70 is positioned on the inner cut portion of the cooling pipe 20 and then inserted into the receiving pocket 20b as the protrusion piece 70a passes through the cutout groove 20a and rotates at a predetermined angle The combination is completed.

After the welding, the work such as welding is performed. In the welding process, the welding process is not necessary.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .

10: mold 20: cooling pipe
30: Refrigerant supply device 40: Supply piping
50: discharge pipe 60: molding sand
70: Heat pipe

Claims (10)

A mold (10) provided for full mold casting;
A cooling pipe (20) inserted into the thick portion of the mold (10);
And a refrigerant supply device (30) for continuously supplying the air refrigerant to the cooling pipe (20)
Wherein a heat dissipation coating layer (23) is formed on the inner surface of the cooling pipe (20) to increase heat radiation efficiency from the mold.
The method according to claim 1,
The cooling pipe 20 is inserted into the thick portion of the mold 10 in such a manner that both side ends 21 and 22 are protruded and one end 21 is connected to the refrigerant supply device 30 to continuously receive the air refrigerant , And the other end (22) is configured to discharge the supplied air refrigerant to the outside.
The method according to claim 1,
Wherein the diameter of the cooling pipe (20) inserted into the mold (10) is adjusted according to the thickness of the mold (10).
The method according to claim 1,
The heat-radiating coating layer (23)
(a) graphite, (b) graphene, (c) epoxy resin binder and (d) silicon oxide, boron nitride, kaolin, aluminum hydroxide, bentonite, talc, mica, Wherein the mold is coated with a heat radiation composition including a heat-dissipating powder selected from the group consisting of magnesium aluminum silicate.
5. The method of claim 4,
Wherein the epoxy resin is a bisphenol-type epoxy resin or a novolak-type epoxy resin.
5. The method of claim 4,
Wherein the heat radiation composition comprises 20 to 30 parts by weight of graphene, 300 to 500 parts by weight of binder, and 100 to 200 parts by weight of heat-radiating powder, based on 100 parts by weight of the graphite. .
The method according to claim 6,
Wherein the heat radiation composition comprises 20 parts by weight of graphene, 400 parts by weight of a bisphenol epoxy resin binder, and 150 parts by weight of magnesium aluminum silicate, based on 100 parts by weight of the graphite. Mold for mold casting.
The method according to claim 1,
Wherein the cooling pipe (20) is formed with a threaded cut portion and the heat dissipating pipe (70) is coupled to the inside of the cutout portion.
9. The method of claim 8,
The heat dissipation pipe 70 is composed of a depression 71 having a constant accommodation space and a flange portion 72 extending to the depression 71 and fixed in contact with the inner wall surface of the cooling pipe 20 Mold for casting molds with anti-shrinkage full mold using air refrigerant.
10. The method of claim 9,
A cutout groove 20a and a protruded piece 70a protruding outside the flange portion 72 of the heat receiving tube 70 and the receiving pocket 20b formed on the upper or lower side of the cutting portion of the cooling pipe 20 are formed The heat dissipating tube 70 is positioned on the inner cutout portion of the cooling pipe 20 and then the protruding piece 70a is inserted into the cutout groove 20a and inserted into the receiving pocket 20b The mold for casting molds according to claim 1,

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