JP5661054B2 - Casting method - Google Patents

Description

  The present invention relates to a casting method using a sand mold, and more particularly to a casting method capable of suppressing defects generated in casting using a core.

For example, a member having a hollow portion, such as a casing of a centrifugal compressor, is cast by a sand mold having a core and a main mold. Both the core and main mold are made by bonding sand with a binder made of resin. Therefore, when the molten metal is poured into the sand mold cavity, the core and the main mold that are in contact with the molten metal are heated to a high temperature, so that the binder is burned and gas (CO ₂ , combustion gas) is generated. The main mold has a high air permeability because the sand has a coarse particle size and its surroundings are in contact with the outside air, so the combustion gas generated in the main mold is easily released to the outside. On the other hand, since the core has low air permeability, the combustion gas generated in the core easily permeates into the surface or inside of the molten metal, resulting in a gas defect in which voids made of combustion gas remain in the casting.
In order to prevent this gas defect, Patent Document 1 proposes that a gas vent hole is formed in a metal core for supporting the core, and combustion gas is discharged from the gas vent hole through the metal core. Yes.

JP 2000-225439 A

Although the proposal of Patent Document 1 is effective in suppressing gas defects, shrinkage nests are listed as another problem in the casting method using the core and the main mold (or outer mold). Shrinkage is a casting defect that occurs when the cooling rate of the molten metal is slow, but shrinkage is likely to occur in the portion facing the core where the cooling rate is slow. As the casting becomes larger, the cooling rate becomes slower, so that the occurrence of shrinkage becomes remarkable.
The present invention has been made based on such a problem, and an object of the present invention is to provide a casting method capable of effectively reducing the generation of shrinkage cavities even in a large casting.

In order to solve the above-mentioned problems, the present inventors have studied to cool a portion where shrinkage cavities are likely to occur using air as a cooling fluid. The air as the cooling fluid passes through the pipe embedded in the part, but as will be described in detail in the section of the embodiment to be described later, if the cooling fluid is fed into the pipe by pressure feeding, the pipe is damaged. I found out that there was a problem. Therefore, in the present invention, the cooling fluid is allowed to pass through by reducing the pressure of the air as the cooling fluid , rather than pumping it. That is, the present invention is a method of casting a casting by solidifying a molten metal filled in a casting cavity formed in a sand mold, wherein the sand mold is embedded in the sand mold along at least a part of the casting cavity. In the casting method, the inside of the cooling pipe communicating with the outside is decompressed, and the molten metal is solidified while allowing air as a cooling fluid to pass through the inside of the cooling pipe.

  When the sand mold in the present invention comprises a main mold and a core, it is preferable to embed a cooling pipe in the core. This is because, as described above, a shrinkage nest is likely to occur in the portion facing the core. Needless to say, this embodiment is only preferable, and the present invention can be applied to a sand mold without a core.

In the casting method of the present invention, it is preferable that the cooling pipe is formed with a vent hole for communicating the inside and the outside.
By sucking the combustion gas based on the binder contained in the sand mold, it is possible to reduce gas defects in the casting caused by the combustion gas.
This vent hole is preferably opened towards the casting cavity. This is because combustion gas is remarkably generated in the surface layer portion of the sand mold in contact with the casting cavity.
Moreover, it is preferable that a sand intrusion prevention member is attached to the vent hole before at least the molten metal is filled into the casting cavity. This is to cope with the possibility of clogging the cooling pipe if sand excessively enters the cooling pipe from the vent hole during molding. In addition, when the cooling pipe with the vent hole has a vertical part inside the front sand mold, a sand reservoir is provided in the vertical part to prevent the sand from falling below it. can do

  In the casting method of the present invention, the inside of the cooling pipe can be depressurized by discharging the cooling fluid from the inside of the cooling pipe by the exhaust fan. In this case, the solidification process required based on the temperature inside the cooling pipe If the discharge flow rate of the cooling fluid by the exhaust fan is controlled according to the cooling rate, the operating efficiency of the exhaust fan can be improved. Similarly, if the discharge flow rate of the cooling fluid by the exhaust fan is controlled according to the concentration of the gas component contained in the cooling fluid discharged from the inside of the cooling pipe, the operation efficiency of the exhaust fan can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the casting method which can reduce generation | occurrence | production of a shrinkage cavity effectively is provided even if it is a large sized casting because a cooling fluid passes the inside of piping, without producing a malfunction in cooling piping.

It is a front sectional view showing the sand mold structure used in the first embodiment schematically. (A) is a top view of the sand mold shown in FIG. 1, and (B) is a side view of the sand mold shown in FIG. It is a front sectional view showing the sand mold structure used in the second embodiment schematically. The example of the sand penetration prevention member attached to the vent hole of the cooling pipe main body of 2nd Embodiment is shown, (A) shows the metal net which covers a vent hole, (B) shows a part of cooling pipe main body as gold | metal | money. An example of replacing with a net tube is shown, and (C) shows an example in which a shield wall is provided facing the gas vent hole. The example of the sand penetration prevention member attached to the vent hole of the cooling pipe main body of 2nd Embodiment is shown, (A) shows the state by which the sealing body 31 is sealed by the vent hole, (B) Indicates a state in which the vent hole is opened by burning the sealing body. The structure of the sand mold | type used for 3rd Embodiment is shown typically, (A) is a front sectional view, (B) is a side view. It is a figure which shows the flow volume adjustment mechanism in 4th Embodiment. It is a flowchart which shows the procedure of the flow volume adjustment in 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. This embodiment is characterized by a sand mold used to cast a member having a cavity. This sand mold consists of a core and a main mold. As is well known, the core is a sand mold disposed inside the main mold and corresponding to the cavity of the member having the cavity. The member is cast by pouring molten metal into a cavity that is a space between the main mold and the core.
In the following description, an example of a box-like simple member having one opening is shown as a member having a hollow portion, but the member to which the present invention is applied is not limited thereto.

[First Embodiment]
As shown in FIGS. 1 and 2, the sand mold 10 in this embodiment includes a main mold 11 and a core 13. By placing the core 13 inside the main mold 11, a casting cavity 15 is formed in the sand mold 10. The casting cavity 15 has a gap shape corresponding to a member cast by the sand mold 10, and a separately prepared molten metal is poured into the casting cavity 15. Note that FIG. 2 omits the description of the exhaust fan 25.
The main mold 11 forms the outer peripheral shape of the member to be cast. Therefore, in this embodiment, since a simple box-shaped member is cast, the main mold 11 also has a box-shaped shape. Moreover, the core 13 forms the cavity part of the said member as mentioned above. Therefore, in this embodiment, it has a rectangular parallelepiped shape.
The main mold 11 and the core 13 can be formed by various known methods. Typically, the main mold 11 and the core 13 are each formed using a compound obtained by mixing sand and a binder. There is no restriction | limiting also in the sand used, Well-known materials, such as mountain sand and silica sand which have silica sand as a main component, can be used.
The sand mold casting method is classified into a raw sand mold method, a carbon dioxide gas method, a shell mold method, and an organic self-hardening sand method according to the binder used, but this embodiment is an organic self-hardening sand using a resin as a binder. Suitable for law application.

  In the present embodiment, a cooling pipe 20 is provided for the core 13. The cooling pipe 20 includes a first header portion 21 provided on a side where air (hereinafter referred to as a cooling fluid) is introduced, a plurality of cooling pipe main bodies 22 branched from the first header section 21, and the cooling pipe main body 22. It consists of a second header part 23. The second header part 23 is connected to the exhaust fan 25. When the exhaust fan 25 is operated, the cooling fluid taken from the first header portion 21 is discharged from the second header portion 23 through the cooling pipe body 22. By continuing this operation during casting, the casting (molten metal) is cooled via the core 13. The first header part 21, the cooling pipe main body 22, and the second header part 23 constituting the cooling pipe 20 all have a hollow structure through which the cooling fluid can pass. In addition, the members constituting the cooling pipe 20 are preferably made of a metal material in consideration of thermal conductivity with the core 13. A metal material should be selected that has a melting point that is at least higher than the melting point of the resulting casting.

The first header portion 21 is exposed to the outside of the core 13, and includes an introduction port 21a into which a cooling fluid is introduced, and a header body 21b that is connected to the introduction port 21a and to which a plurality of cooling pipe bodies 22 are connected. I have.
The cooling pipe body 22 is embedded in the core 13 so as to be along and close to the casting cavity 15. The distance L from the surface of the core 13 to the casting cavity 15 to the cooling pipe body 22 is preferably about 50 to 100 mm, although it depends on the size and shape of the casting to be cast. If it is less than 50 mm, it is not easy to sufficiently harden the surface layer portion of the core 13 closer to the surface than the cooling pipe main body 22, and if it exceeds 100 mm, the casting may not be sufficiently cooled.
The second header portion 23 includes a header main body 23a to which a plurality of cooling pipe main bodies 22 are connected, and a discharge port 23b through which the cooling fluid that has passed through the cooling pipe main body 22 is discharged while continuing to the header main body 23a. Yes.
When the exhaust fan 25 is operated, the cooling fluid taken in from the introduction port 21a is supplied to each cooling pipe main body 22 via the header main body 21b. After passing through each cooling pipe main body 22, the cooling fluid reaches the exhaust fan 25 through the header main body 23 a and the discharge port 23 b and is discharged to the outside of the exhaust fan 25. Regardless of the type, the exhaust fan 25 can widely apply equipment capable of discharging the cooling fluid from the inside of the cooling pipe body 22 and reducing the pressure. For example, known means such as an ejector, a pump, and a fan can be applied. 1 and 3 show an example in which an ejector is applied.
By passing the cooling fluid through each cooling pipe main body 22, the surface layer portion between the casting cavity 15 and the cooling pipe main body 22 in the core 13 is cooled, so that the cooling rate of the casting in the solidification process is increased, and the shrinkage nest is formed. Can be suppressed.

The present embodiment is characterized in that the cooling fluid is allowed to pass through the cooling pipe 20 (cooling pipe body 22) using the exhaust fan 25. This feature is clarified by comparing with a method of pumping the cooling fluid from the first header portion 21, for example.
When pouring (for example, molten metal temperature: 1500 ° C.) into the casting cavity 15, the temperature of the cooling tube main body 22 as well as the core 13 rapidly increases. Along with this, the pressure of the cooling fluid passing through the inside of the cooling pipe main body 22 rapidly increases. Therefore, it was confirmed that when the cooling fluid was fed into the cooling pipe main body 22 by pressure feeding, the pressure due to the pressure feeding also helped, and the cooling pipe main body 22 was damaged without being able to withstand the increased pressure. In addition, the cooling pipe body 22 expands even if it does not reach breakage, and it is confirmed that the core 13 is deformed or broken by pushing the surface layer portion of the core 13 toward the casting cavity 15 in particular. It was done. Although measures can be taken to increase the strength of the cooling pipe body 22 by increasing the thickness thereof, this is not a preferable measure from the viewpoint of promoting cooling of the casting.
Therefore, in this embodiment, the pressure inside the cooling pipe main body 22 is suppressed to an atmospheric pressure or lower by using the exhaust fan 25 and allowing the cooling fluid to pass through while reducing the pressure inside the cooling pipe main body 22. By doing so, the pressure rise inside the cooling pipe main body 22 during casting is suppressed, and the cooling pipe main body 22 is prevented from being damaged.

  As described above, according to the present embodiment, the inside of the cooling pipe main body 22 is decompressed during casting to prevent damage to the cooling pipe main body 22 due to the pressure increase in the pipe, while the core 13, particularly the surface layer portion, is prevented. By cooling, the shrinkage cavity of the casting can be reduced.

In the present embodiment, it is recommended that the cooling pipe body 22 be a flexible pipe, typically a flexible pipe. As shown in FIGS. 1 and 2, the cooling pipe main body 22 has a portion that bends inside the core 13, and when the core 13 has a complicated shape, the cooling pipe body 22 follows the shape. This is because it is easy to bend. However, the present invention allows a plurality of straight pipes to be connected to form the cooling pipe body 22 having a bent portion.
Moreover, although this embodiment showed the form which aggregates the several cooling pipe main body 22 using the 1st header part 21 and the 2nd header part 23, it is a wind exhauster in each of the independent multiple cooling pipe main body 22. FIG. A form in which 25 is connected and sucked can be adopted. In addition, it is not essential to provide a plurality of cooling pipe bodies 22, and if the area to be cooled is small, one cooling pipe body 22 may be sufficient, and even if the area to be cooled is wide, one cooling pipe is sufficient. The main body 22 may meander to correspond to the region.
Furthermore, although this embodiment demonstrated the example which provides the cooling piping 20 in the core 13, if not only the core 13 but wants to accelerate | stimulate cooling, the cooling piping 20 can also be provided in the main mold | type 11 side. The cooling pipe 20 can also be provided in a sand mold that does not include the core 13.

[Second Embodiment]
The basic configuration of the second embodiment is the same as that of the first embodiment. However, as shown in FIG. 3, the second embodiment is characterized in that a gas vent hole 26 into which the combustion gas G flows is provided in the cooling pipe body 22. have. The vent hole 26 communicates the inside and the outside of the cooling pipe main body 22.
In the second embodiment, since the vent hole 26 is provided in the cooling pipe 20, when the exhaust fan 25 is operated during casting, the combustion gas G generated particularly in the surface layer portion of the core 13 passes through the vent hole 26. Then, it is sucked into the cooling pipe main body 22. Therefore, the gas defect of the casting resulting from the combustion gas G can be reduced.

In the present embodiment, in order to effectively suck the combustion gas into the cooling pipe main body 22 and further reduce gas casting defects, it is preferable to set the positions and number of the gas vent holes 26 as follows.
The vent hole 26 is preferably provided toward the casting cavity 15. This is because the combustion gas is remarkably generated in the surface layer portion of the core 13 in contact with the casting cavity 15.
Further, the vent holes 26 are provided intermittently along the longitudinal direction of the cooling pipe main body 22. However, in the drawing, the lower side of the core 13 is less likely to escape heat from the upper side, and the cooling rate of the surface layer portion of the core 13 is slower, so the combustion gas tends to stagnate. Therefore, it is desirable to provide more gas vent holes 26 in the horizontal portion 22H of the cooling pipe body 22 located on the lower side than in the vertical portion 22V as shown in FIG. For the same reason, it is desirable to provide more vent holes 26 on the lower side of the vertical portion 22V of the cooling pipe body 22 than on the upper side.

  Next, when the core 13 is formed, there is a possibility that sand may enter the inside of the cooling pipe main body 22 through the gas vent hole 26. The horizontal portion 22H of the cooling pipe main body 22 where the gas vent hole 26 is opened downward has little sand intrusion, but the vertical portion 22V provided along the vertical direction is formed because the gas vent hole 26 opens in the horizontal direction. There is a high possibility that sand will enter. Therefore, it is desirable to attach a sand intrusion prevention member to the vent hole 26 provided in the portion. This sand intrusion prevention member is provided to the cooling pipe main body 22 gas vent hole 26 from before molding.

Although the specific form of the sand intrusion prevention member is not limited in the present invention, some preferred forms will be described below.
As shown in FIG. 4A, a wire mesh 28 covering the gas vent hole 26 can be used as a sand intrusion prevention member. The wire mesh 28 is attached to the cooling pipe main body 22 before molding the core 13. The wire mesh 28 preferably has a mesh smaller than the particle diameter of the sand constituting the core 13 in order to completely prevent sand from entering. As an example of the sand intrusion prevention member using a wire mesh, as shown in FIG. 4B, a part of the cooling tube main body 22 can be replaced with a wire mesh tube 29 formed in a tubular shape. Further, in place of the wire mesh, sand can be prevented from entering by providing a metallic shield wall 30 opposite to the gas vent hole 26 as shown in FIG.
Further, as shown in FIG. 5A, a sealing body 31 made of a resin material can be used as a sand intrusion prevention member. Since the sealing body 31 seals the gas vent hole 26 until the molten metal is poured, sand is prevented from entering the cooling pipe body 22 during the molding of the core 13. However, since the sealing body burns when the molten metal is poured, as shown in FIG. 5B, the gas vent hole 26 is opened, and the combustion gas generated in the core 13 is sucked. The sealing body can be formed of the same material as the resin contained in the core 13 as a binder. In this case, the combustion gas caused by the core 13 and the combustion gas caused by the sealing body are the same.

[Third Embodiment]
The second embodiment focuses on preventing sand from entering. However, although not preferred, the present invention allows sand to enter the cooling tube body 22. However, it must be avoided that the invading sand clogs the cooling pipe body 22. As described above, the sand easily invades the vertical portion 22V of the cooling pipe body 22, and the sand that has entered here falls into the intersection 22C (FIG. 6) between the vertical portion 22V and the horizontal portion 22H. To do. Therefore, even if sand invades, if it is possible to prevent all of the sand from falling to the intersection 22C, the pressure loss of the cooling pipe main body 22 increases, and further, the possibility that the cooling pipe main body 22 is clogged decreases. Further, when sand enters the intersecting portion 22C, the contact area between the inside of the cooling pipe main body 22 and the cooling fluid in the portion becomes small, so that the cooling capacity in the portion decreases. As described above, the heat on the lower side of the core 13 is less likely to escape from the upper side, and in particular, it is required to secure the cooling capacity on the lower side of the core 13. The third embodiment proposes means for suppressing the invading sand from falling to the intersection 22C.

In the third embodiment, as shown in FIG. 6, a sand reservoir 221 is provided in the vertical portion 22V. The sand reservoir 221 is configured by providing a portion along the horizontal direction in the middle of the vertical direction of the vertical portion 22V.
Sand that has entered from the vent hole 26 of the vertical portion 22V above the sand reservoir 221 stays in the sand reservoir 221 and does not fall to the intersection 22C. Sand that has entered through the vent hole 26 of the vertical portion 22V above the sand reservoir portion 221 falls to the intersection 22C, but about half of all the sand that enters the entire area of the vertical portion 22V falls. The amount of fall can be suppressed. Therefore, it is possible to reliably ensure the cooling capacity at the intersection 22C. In the present embodiment, the sand reservoir 221 is provided at a location corresponding to the middle of the vertical portion 22V, but the present invention is not limited to this configuration. For example, you may provide in places other than the middle of the perpendicular direction according to the size and shape of the sand mold 10 (the main mold 11 and the core 13). Moreover, when the size of the sand mold 10 (the main mold 11 and the core 13) is large, a plurality of sand reservoirs 221 may be provided in the vertical direction. Furthermore, you may provide the sand reservoir part 221 of the form which the cooling pipe main body 22 meanders up and down with respect to the perpendicular direction.

[Fourth Embodiment]
4th Embodiment demonstrates the example which controls the flow volume of the cooling fluid which passes the cooling pipe main body 22 by adjusting operation | movement of the exhaust fan 25. FIG. In addition, the cooling pipe 20 and the exhaust fan 25 follow the second embodiment.
As shown in FIG. 7, the fourth embodiment includes a thermometer 41 that measures the internal temperature of the cooling pipe main body 22 (horizontal portion 22 </ b> H) using, for example, a thermocouple, and the cooling fluid discharged from the exhaust fan 25. The gas concentration meter 42 for measuring the concentration of the gas component (CO ₂ ) to be collected, the flow rate adjusting device 43 for adjusting the flow rate of the cooling fluid sucked by the exhaust fan 25, and the control device 40 are provided.

As shown in FIG. 8A, the control device 40 acquires the temperature data measured by the thermometer 41 and the gas concentration data measured by the gas concentration meter 42 (FIG. 8A, steps S101 and S103). .
The control device 40 calculates the molten metal cooling rate R based on the acquired temperature data (FIG. 8A, step S105), and calculates the combustion gas emission amount V based on the acquired gas concentration data (FIG. 8). (A) Step S107).
The control device 40 adjusts the flow rate based on the calculated molten metal cooling rate R and the combustion gas discharge amount V to determine the flow rate (steps S109 and 111 in FIG. 8A). The procedure for adjusting and determining the flow rate is shown in FIG. This will be described below.

In the flow rate adjustment and determination, the flow rate Q ₁ determined based on the cooling rate R and the flow rate Q ₂ determined based on the combustion gas discharge amount V are obtained, and the larger flow rate (max (Q ₁ , Q ₂ )) Is adopted.

Flow rate Q ₁ is determined as follows.
The control device 40 compares the calculated cooling rate R (step S201 in FIG. 8B) with the reference cooling rate _R0 (step S203 in FIG. 8B). The reference cooling rate R ₀ is a reference value at which no shrinkage cavity is formed in the casting when it is cooled at a rate higher than that. Therefore, the reference cooling rate _R0 is determined according to the specifications of the casting to be cast.
If the cooling rate R is slower than the reference cooling rate _R0 (YES in step S203), the control device 40 determines that the flow rate is increased (flow rate UP) (FIG. 8B, step S205). On the other hand, if the cooling rate R is equal to or higher than the reference cooling rate _R0 (NO in step S203), the control device 40 determines that the previous value is maintained and the flow rate is not changed (step S207 in FIG. 8B). Controller 40 determines the flow rate UP (step S205) or determines the flow rate control without based on either (step S207), and determines the flow rate _{Q 1} temporarily (see FIG. 8 (B) Step S209) .

Flow rate Q ₂ is determined as follows.
Controller 40, the combustion gases was calculated emissions V (FIG. 8 (B) step S301) comparing the reference emission amount _{V 0} (FIG. 8 (B) step S303). The reference emission amount V ₀ is a reference value that causes no gas defects when the combustion gas is sucked with the above-mentioned emission amount. Therefore, the reference emission amount V ₀ is also determined in accordance with the specifications of the casting to be cast.
The less than the combustion gas emissions V is the reference emission amount _{V 0} (step S303 YES), the controller 40 increases the flow rate (flow rate UP) as the determining (see FIG. 8 (B) step S305). On the other hand, if the combustion gas emission amount V is greater than or equal to the reference emission amount V ₀ (NO in step S303), the control device 40 determines that the previous value is maintained and the flow rate is not changed (step S307 in FIG. 8B). . Controller 40 determines the flow rate UP (step S305) or determines the flow rate control without based on either (step S307), and determines the flow rate _{Q 2} temporarily (see FIG. 8 (B) Step S309) .

The control device 40 finally determines the flow rate (max (Q ₁ , Q2)), which is the larger one of the primarily determined flow rate Q ₁ and flow rate Q ₂ , as the flow rate to be controlled (FIG. 8B, step S 311). . The control device 40 controls the flow rate adjusting device 43 so that the flow rate by the exhaust fan 25 becomes the determined flow rate (max (Q ₁ , Q ₂ )).

As described above, according to the fourth embodiment, it is possible to efficiently reduce the shrinkage cavity and gas defects of the casting by operating the exhaust fan 25 without waste.
In the fourth embodiment, seeking both flow Q ₂ to which is determined on the basis of the flow rate Q ₁ that is determined based on the cooling rate R to the combustion gas emissions V, but the present invention is one of either It is allowed to control the operation of the exhaust fan 25 based on the flow rate.

In the above embodiment, the sand mold 10 without the core 13 has been described as an example. However, it is obvious to those skilled in the art that the effect of the present invention can be enjoyed even when applied to a sand mold without the core.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

DESCRIPTION OF SYMBOLS 10 Sand mold 11 Main mold 13 Core 15 Casting cavity 20 Cooling piping 21 1st header part 21a Inlet 21b Header main body 22 Cooling pipe main body 22C Crossing part 22H Horizontal part 22V Vertical part 221 Sand reservoir 23 Second header part 23a Header main body 23b Exhaust port 25 Ventilator 26 Degassing hole 28 Wire mesh 29 Wire mesh tube 30 Shield wall 31 Sealing body 40 Control device 41 Thermometer 42 Gas concentration meter 43 Flow rate adjusting device

Claims (8)

A method of casting a casting by solidifying molten metal filled in a casting cavity formed in a sand mold,
Air inside the cooling pipe is allowed to pass through the inside of the cooling pipe by depressurizing the inside of the cooling pipe that is embedded in the sand mold along at least part of the casting cavity and communicates with the outside of the sand mold. While solidifying the molten metal,
A casting method characterized by the above. The sand mold consists of a main mold and a core,
The cooling pipe is embedded in the core,
The casting method according to claim 1. In the cooling pipe, a gas vent hole that communicates the inside and the outside is formed.
The casting method according to claim 1 or 2. The vent hole is opened toward the casting cavity.
The casting method according to claim 3. The degassing hole is provided with a sand intrusion prevention member at least before the molten metal is filled into the casting cavity.
The casting method according to claim 3 or 4. The cooling pipe having the vent hole has a vertical portion inside the sand mold,
The vertical portion is provided with a sand reservoir.
The casting method as described in any one of Claims 3-5. The decompression is performed by an exhaust fan,
According to the cooling rate of the solidification process obtained based on the temperature inside the cooling pipe, the discharge flow rate of the cooling fluid by the exhaust fan is controlled.
The casting method as described in any one of Claims 1-6. The decompression is performed by an exhaust fan,
According to the concentration of the gas component contained in the cooling fluid discharged from the inside of the cooling pipe, the discharge flow rate of the cooling fluid by the exhaust fan is controlled.
The casting method as described in any one of Claims 3-6.

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