JP3644422B2 - Method for cooling mold and casting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold capable of cooling a casting with a cooling medium and a casting cooling method.
[0002]
[Prior art]
Several methods have been proposed in the past to increase the cooling rate of castings in order to shorten the time from pouring to unraveling.
[0003]
One is to install a pipe in a mold, and to cool the foundry sand by passing a refrigerant through the pipe or the like. For example, as shown in FIGS. 7 and 8 proposed in Japanese Patent Laid-Open No. 57-103775. There is a way.
[0004]
This is because the casting pipes 111 and 113 solidified with the molds 110 and 112 and the casting space 104 made of a wooden mold or the like, or a mold made of a disappeared model such as foamed polystyrene, a cooling pipe 130 is embedded in the casting sands 111 and 113 in advance. Then, as shown in FIG. 8, after the molten metal is poured and the casting is cast, a cooling medium C such as water or air is circulated in the cooling pipe 130 to forcibly cool the casting. If the casting can be cooled uniformly, deformation of the casting can be prevented.
[0005]
Another method is to inject and infiltrate a coolant such as water into the mold after pouring the molten metal, and quickly cool the casting with this coolant, for example, Japanese Patent Laid-Open No. 9-225621. Has been proposed. The cooling liquid to be injected is not directly applied to the casting, but is poured into a mold in which the casting is submerged, so that the inside penetrates and the heat of the casting is taken through the casting sand. At that time, not only the rise in water temperature but also high latent heat of vaporization is utilized.
[0006]
[Problems to be solved by the invention]
However, in the former conventional example, since it is necessary to form a large number of cooling pipes 130 so as to follow the surface shape while keeping the same distance from the surface of the casting, it is necessary to install them side by side. It is difficult to install the cooling pipe 130 for a casting having a free curved surface, and as a result, the casting cannot be uniformly cooled, resulting in a large deformation after the casting is completed.
[0007]
In addition, a large number of man-hours are required to install the cooling pipe 130 because a large number of cooling pipes 130 are bent and installed in the mold prior to filling the moldings 110 and 112 with the foundry sand 111 and 113. There was a problem that it took.
[0008]
Further, in the latter conventional example, when the water pipe for injecting the cooling liquid is embedded in the mold, it is still difficult to arrange the water pipe uniformly along the surface of the casting, and as a result, the casting cannot be uniformly cooled, There was a problem that deformation after completion became large.
[0009]
Then, this invention is made | formed in view of the said problem, and it aims at providing the casting_mold | template and the cooling method of a casting which can cool a casting uniformly.
[0010]
[Means for Solving the Problems]
The first invention uses casting sand into the mold relates to a mold for forming a molding space of the casting, and the thickness of the forming surface of the forming space of the casting substantially identical to at least part of the surface of the mold A cooling surface is formed on the casting sand surface, a cooling space formed between the cooling surface and a mold, a filler uniformly filled in the cooling space, and a cooling medium is circulated in the cooling space. In the mold constituted by the cooling means for cooling the cooling surface, the cooling surface is formed by cutting the molding sand on the back surface of the divided surface of the mold or removing the molded wooden mold previously embedded in the molding sand, The cooling space is formed between a lid member that covers the mold with the back surface.
[0011]
The cooling surface is desirably formed on the entire peripheral surface of the casting, but it is practical to target a casting portion that requires shape accuracy.
[0012]
The cooling means may be any means for bringing the cooling medium into contact with the cooling surface, and it is desirable to inject and circulate the cooling medium in a space formed with the cooling surface in the mold.
[0013]
The mold includes a frame surrounding the periphery of the foundry sand and / or a lid member, and a space between the mold and the cooling surface is formed in the cooling space.
[0014]
According to a second invention, in the first invention, the cooling means circulates a cooling medium through a gap between fillers in the cooling space.
[0015]
When the filler is formed in a spherical shape, a gap whose cross-sectional area can be regulated to a predetermined size can be formed between the fillers, which is optimal when used for the passage of the cooling medium.
[0017]
A third invention relates to a method, wherein a casting molding space is formed in a mold by using foundry sand in a mold, and at least a part of the surface of the casting mold has a thickness from a forming surface of the casting molding space. After forming the cooling surface in the same manner, forming the cooling surface in a cooling space closed with the inner surface of the mold or the lid member, filling the cooling space with the filling member, and pouring the molten metal into the casting molding space In the casting cooling method in which the cooling medium is circulated through the gap between the filling members, the cooling surface is formed by cutting the molding sand on the back surface of the divided surface of the mold or by removing the molded wooden mold previously embedded in the casting sand. A cooling space is formed between the cooling surface and the inner surface of the lid member by covering the back surface of the mold with a lid member.
[0018]
The mold includes a frame surrounding the periphery of the foundry sand and / or a lid member, and a space between the mold and the cooling surface is formed in the cooling space.
[0020]
【The invention's effect】
Therefore, in the first and third aspects of the invention, the cooling space is formed by the cooling surface of the casting sand surface and the mold by making the thickness from the forming surface of the casting molding space the same on at least a part of the surface of the mold. Thus, since the cooling medium is filled in the cooling space and the cooling medium is circulated, the casting surface can be uniformly cooled, and deformation after the casting is completed can be reduced.
And because the cooling surface is formed by cutting the molding sand on the back of the mold dividing surface or by removing the molded wooden mold that is pre-embedded in the molding sand, the cooling area can be increased and even large castings can be cooled uniformly. The deformation after the casting is completed can be reduced.
[0021]
Moreover, since the cooling space is filled with the spherical filler, the foundry sand and the foundry weight can be held without being deformed or damaged.
[0022]
In the second invention, in addition to the effect of the first invention, the cooling medium is circulated through the gaps between the fillers in the cooling space, so that installation of a cooling pipe or the like for circulating the cooling medium is unnecessary. Mold production time can be greatly reduced.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an example of a mold to which the present invention is applied. An upper mold 1 having a gate 2, a lower mold 3 having a casting molding space 4, and a lid member fixed below the lower mold 3. 5.
[0025]
The upper mold 1 includes casting sand 11 filled and solidified in a mold 10, and its lower surface forms a dividing surface 6 with the lower mold 3, and includes a gate 2 penetrating vertically. A hot water reservoir 7 is disposed at the upper open end of 2 to enlarge the water gate 2 and form a reservoir.
[0026]
The lower die 3 has a casting molding space 4 partially opened on the dividing surface 6 with the upper die 1 and has a molding sand 13 filled in the mold frame 12 and solidified, and the casting molding space 4 is It is formed continuously with the gate 2 of the upper mold 1. The molding space 4 may be in a state where a disappearance model is inserted.
[0027]
The lower surface of the molding sand 13 surrounding the molding space 4 of the casting of the lower mold 3 is a mold surface 8 (hereinafter referred to as a cooling surface or a cooling surface) recessed upward from the joint surface 7 with the lid member 5 of the lower mold 3. The cooling surface 8 is formed so as to have a predetermined interval (thickness) with respect to the forming surface 9 that forms the molding space 4 of the casting. That is, the casting molding space 4 has a uniform thick sand 13 between them so that the cooling surface 8 exists at an equal distance on any surface on the lid member 5 side. The thickness of the foundry sand 13 requires a thickness of the foundry sand 13 that can sufficiently withstand the pouring pressure of the molten metal.
[0028]
The lid member 5 forms a space 15 by a peripheral edge 14 coupled to the frame 12 of the lower mold 3 and a mold surface 8 which is connected to the peripheral edge 14 and is recessed upward of the lower mold 3. The peripheral part 14 is formed with an inlet 17 for introducing the cooling medium C into the space part 15 and an outlet 18 for discharging the cooling medium C in the space part 15.
[0029]
A space 15 formed by the lid member 5 and the mold surface 8 of the lower mold 3 is filled with a spherical filler 19 made of metal or resin. Since the filling material 19 is spherical, it can be filled with a uniform density even when the shape of the mold surface 8 is complicated or has a three-dimensional free-form surface, and the filling materials 19 are in contact with each other by filling. Even in the state, it is a partial contact state, and permits the circulation of the cooling medium C such as water or air. Further, as the material of the filler 19, any material may be selected as long as it has a strength capable of withstanding the weight of the molten metal poured into the mold and the weight of the foundry sand itself.
[0030]
The example shown in the figure shows a casting mold when the press mold is cast in an inverted state, and the lower part in the figure forms the press surface, and the three members extending upward from the press surface are the legs of the press mold. In this case, since the portion that minimizes deformation after casting is the press surface, the molding sand 13 forming the press surface is formed to a predetermined uniform thickness. is there. If necessary, although not shown, the thickness of the foundry sand 13 forming other portions may also be formed to a predetermined uniform thickness. In that case, the space part formed on the mold surface having a predetermined thickness is filled with a filler made of a sphere like the above, and the inlet through which the cooling medium flows in the space part filled with the filler. And form an outlet.
[0031]
The mold surface 8 formed on the lower foundry sand is manufactured by the steps shown in FIGS. FIG. 2 shows a state in which the upper mold 1 and the lower mold 3 filled with the foundry sands 11 and 13 and solidified on the molding table 20 are placed upside down, and the upper mold 1 and the lower mold 3 have a casting-shaped cavity. 4 is formed, or the disappearance model is buried.
[0032]
As shown in FIG. 2, the casting sand 13 is cut with a cutting tool T from below the lower mold 3 (upper in the figure) to form a mold surface 8. The shape of the mold surface 8 can be easily adjusted by adding dimensions to the casting shape by the thickness of the casting sand 13 (offset the coordinate position of each point of the casting shape by the thickness of the casting sand). The position can be determined. As described above, the thickness of the foundry sand 13 in this case is determined so as to leave the thickness of the foundry sand 13 that can withstand the pouring pressure during casting.
[0033]
The molding of the mold surface 8 is not limited to the molding method using the cutting tool T as described above, and may be formed by a wooden mold M having a surface imitating the mold surface 8 in advance. That is, before the lower mold 3 is filled with the foundry sand 13, the wooden mold M is combined with the lower mold 3 to form the lower part of the mold 12, the cast molding wooden mold is positioned, and the foundry sand 13 is filled and solidified. Then, even if the upper mold 1 and the lower mold 3 are arranged in an inverted state in the state of FIG. 2 and the wooden mold M is extracted upward, the mold surface 8 can be formed in the same manner as in the above method.
[0034]
When the mold surface 8 is formed, the space portion 15 and the space portion 15 are filled with a spherical filler 19, and after a predetermined amount is filled, a pipe for circulating a cooling medium C such as water or air can be attached. The lid member 5 is attached by fixing the peripheral edge portion 14 to the mold 12 of the lower mold 3. After that, the filler 19 is filled into the space 15 between the lid member 5 and the mold surface 8. The mold of FIG. 3 that has been filled is filled with a uniform density in the space portion 15 because the filler 19 is spherical, and the mold surface 8 that forms the space portion 15, the lid member 5, and the lower mold 3. Are uniformly in contact with the side walls along the mold 12.
[0035]
Next, the mold of FIG. 1 can be configured by inverting the entire mold including the cover member 5 and removing the molding table 20.
[0036]
The effect | action which injects the molten metal to the casting_mold | template of the said description and forms a casting is demonstrated below. 1, the upper mold 1 and the lower mold 3 are joined at the dividing surface 6 to connect the molds 10 and 12, and the lid member 5 and the mold 12 and the peripheral edge 14 of the lower mold 3 are connected to each other. The space 15 formed by being connected and integrally formed by the mold surface 8 and the lid member 5 is filled with a spherical filler 19, and the inlet 17 and outlet 18 of the peripheral edge 14 of the lid member 5 are a cooling medium. C is connected to the storage device.
[0037]
When molten metal is poured into the hot water pool 7 of the upper mold 1, the molten metal flows into the casting space 4 via the gate 2 and fills the casting space 4. When the casting space 4 is formed of a disappearing model, the casting space 4 is filled with molten metal while sublimating the disappearing model. At this time, the foundry sand 13 forming the foundry space 4, particularly the foundry sand 13 forming the mold surface 8, is not damaged because a sufficient thickness is ensured as described above, and is spherical. The filler 19 also withstands this weight and is not damaged.
[0038]
After the pouring is completed, as shown in FIG. 4, the cooling medium C of the storage device (not shown) is introduced into the space 15 from the inlet 17 of the peripheral portion 14 of the lid member 5, and is discharged from the outlet 18 to the storage device. Circulate. The cooling medium C introduced into the space 15 passes through the gaps between the fillers 19 because the filler 19 has a spherical shape, and the mold surface 8 formed by the foundry sand 13 facing the space 15 is removed. Cooling.
[0039]
This cooling state will be described in detail with reference to FIG. 5 which shows the relationship between the casting sand thickness and the temperature by modeling from the casting, the casting sand, the filler, and the cooling medium.
[0040]
Here, the temperature of the casting: t1
Temperature of cooling medium C: t2
Foundry sand surface area: F
Heat flow time: θ
Foundry sand thickness: b
Thermal conductivity of foundry sand: λ
Then, the heat quantity Q flowing through the foundry sand is obtained by the following equation (1) Q = λ × F × θ × (tl−t2) / b (1). When the equation (1) is modified, the following equation (2) (tl-t2) = (Q × b) / (F × θ × λ) (2) is obtained. From this equation (2), it can be seen that the temperature difference between the casting and the cooling medium C is proportional to the thickness of the foundry sand. Therefore, by making the thickness of the foundry sand constant, it is possible to uniformly cool the target cast-shaped portion of the foundry.
[0041]
FIG. 6 shows the relationship between the temperature difference in the casting and the deformation by a relatively simple casting sample D, where
Cross-sectional area of casting upper part: A1
Cross-sectional area of the casting lower part: A2
Linear expansion coefficient: α
Temperature difference between upper and lower castings: △ T
Casting height: H
Casting length: L
Sectional moment of inertia: I
Then, the deformation (warp) S of the casting is expressed by the following equation (3) S = (A1 × A2 × α × ΔT × H × L ² ) / (8 × I × (A1 + A2)) (3) Obtained by the formula From this equation (3), it can be seen that the deformation of the casting is proportional to the temperature difference ΔT. Similarly, in a casting having a free-form surface, the temperature difference ΔT and the deformation of the casting are proportional. Therefore, deformation of the casting can be reduced by cooling the casting uniformly.
[0042]
In this embodiment, the following effects are obtained. That is, in order to cool the casting by bringing the cooling medium C into contact with the cooling surface 8 formed on the casting sand surface with the thickness from the forming surface of the casting molding space 4 substantially the same as at least a part of the surface of the mold, The casting surface can be uniformly cooled, and deformation after the casting is completed can be reduced.
[0043]
The cooling surface 8 forms a cooling space 15 between the mold 12 or the inner surface of the lid member 5, and the cooling space 15 is filled with a spherical filler 19. Can be held without being deformed or damaged.
[0044]
Since the cooling medium C is circulated through the gaps between the fillers 19 in the cooling space 15, it is not necessary to install a cooling pipe or the like for circulating the cooling medium C, and the mold manufacturing time can be greatly shortened.
[0045]
Since the cooling surface 8 is formed by cutting the molding sand 13 on the back side of the dividing surface 6 of the mold or by removing the molded wooden mold M previously embedded in the molding sand, the cooling area can be increased, and even a large casting is uniform. It is possible to reduce the deformation after the casting is completed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a mold showing an embodiment of the present invention.
FIG. 2 is an explanatory view showing the former stage of the mold manufacturing process.
FIG. 3 is an explanatory view showing the latter stage of the mold manufacturing process.
FIG. 4 is an explanatory view showing a casting process using a mold.
FIG. 5 is an explanatory diagram showing the relationship between the thickness of foundry sand and temperature.
FIG. 6 is an explanatory diagram showing a relationship between a temperature difference in a casting and deformation.
FIG. 7 is a cross-sectional view showing a conventional mold.
FIG. 8 is a cross-sectional view showing a cooling state by a conventional mold.
[Explanation of symbols]
1 Upper mold 2 Sprue 3 Lower mold 4 Casting molding space (casting space)
5 Lid member 6 Dividing surface 8 Mold surface (cooling surface, cooling surface)
9 Casting formation surface 10, 12 Formwork 11, 13 Casting sand 15 Space (cooling space)
19 Filler

Claims (3)

It relates to a mold that forms molding space of casting using casting sand in the mold,
A cooling surface is formed on the surface of the casting sand by making the thickness from the forming surface of the casting molding space substantially the same on at least a part of the surface of the mold, and a cooling space formed between the cooling surface and the mold frame,
A filler uniformly filled in the cooling space;
In a mold comprising cooling means for circulating the cooling medium in the cooling space and cooling the cooling surface ,
The cooling surface is formed by cutting the molding sand on the back of the mold dividing surface or by removing a molded wooden mold embedded in the molding sand in advance.
The said cooling space is formed between the lid | cover members which cover a casting_mold | template with the said back surface, The casting_mold | template characterized by the above-mentioned .   2. The mold according to claim 1, wherein the cooling means circulates a cooling medium through a gap between fillers in the cooling space. Form molding space in the mold using foundry sand in the mold,
At least a part of the surface of the mold is formed on the cooling surface with the same thickness from the forming surface of the casting molding space,
Forming the cooling surface in a cooling space closed by the inner surface of the mold or the lid member;
Wherein the filling member to the cooling space is filled, after pouring the molten metal into the molding space of the casting, the cooling method of cast product Ru circulates coolant through the gap of the filling member,
The cooling surface is formed by cutting the molding sand on the back side of the divided surface of the mold or removing the molded wooden mold previously embedded in the molding sand,
A casting cooling method , wherein a cooling space is formed between the cooling surface and the inner surface of the lid member by covering the back surface of the mold with a lid member .

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