JP2004034042A - Method for molding frozen mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for molding a frozen mold in which a suitable additive is added to a silica sand, foam generated by entrained air when mixing is increased, the generated foam is retained in stable state, a flowing sand capable of fluidizing the mold sand is formed and a flowing mold formed by using the flowing sand is frozen, in the method for molding the frozen mold comprising the casting sand obtained by adding a predetermined quantity of water to the silica sand. <P>SOLUTION: In the mixing process 11 of the silica sand, the flowing sand 12a having flowability and moldability is formed, by generating fine cells by the entrained air in a large quantity, by adding water 10 and adding sulfo succinic acid beef tallow amide based surfactant 10a, the foam is generated by adding a organic substance 10b having NCO group and by its reaction with the water, and mechanism absorbing the deforming of the form stably retaining the foam is provided, and the flowing mold 12b is molded. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a freezing mold that forms a mold by filling around a model incorporated in a mold frame with molding sand mixed with a predetermined amount of water to form a mold, and hardens the obtained mold by freezing to obtain a frozen mold. In the molding method of
In order to give fluidity to the molding sand containing a predetermined amount of water to be filled around the model, a predetermined surfactant is added, and even a model having a complicated shape is easily filled and molded around the model. The present invention relates to a method for forming a frozen mold by preparing a mold and hardening the formed fluid mold by freezing to obtain a frozen mold.
[0002]
[Prior art]
A method for manufacturing a frozen mold in which a predetermined amount of water is mixed with the foundry sand and the mold formed using the mixed foundry sand is frozen to produce a frozen mold is disclosed in, for example, JP-B-56-30107. ing.
According to the invention disclosed in the above publication, a liquefied gas such as nitrogen or dry ice is used as a refrigerant used for freezing.
Japanese Patent Application Laid-Open No. H11-138235 discloses a method for freezing low-temperature air by using a refrigerator to pass through a mold.
[0003]
By the way, as for the fluid mold, silica sand is used as an aggregate, water glass or cement as a binder, phosphoric acid, a self-hardening mold using an inorganic binder such as sodium aluminate, Similarly, for a self-hardening mold or a gas curing mold using an organic binder such as a resin component such as a furan resin, a phenol resin, or a urethane resin as a binder, a fluid molding method is used.
In other words, in the cement fluid molding method, a method is used in which cement, water and a surfactant are added to silica sand, kneaded with a mixer to form fluid sand, and poured into a casting flask.
In the case of a water glass-based self-hardening mold, a method has been adopted in which water glass and a surfactant are added to silica sand, kneaded with a mixer to form fluidized sand, and then poured into a casting flask.
[0004]
On the other hand, in the case of conventional molds used for frozen molds that are not fluid molds, complicated molds for products with complicated shapes that cannot be sanded by hand or machine require complicated work via cores and split molds. Although it is necessary, if a fluid mold is possible, a mold for a complicated product can be easily formed only by pouring in the liquid sand.
However, in the case of a fluid mold molding method used for a self-hardening mold or a gas-curing mold using the organic binder, a mold for a complicated model can be easily formed only by pouring fluid sand into a mold as described above. However, it has the following problems.
[0005]
That is, in the fluid molding method using an inorganic binder such as the cement or water glass,
Since binders such as cement and water glass, which are binders, are inorganic, it is difficult to reuse the molding sand of a mold that has been hardened once, and a great deal of labor is required to reuse it.
Further, even when a fluid mold is made of an organic binder such as furan or phenol and water, there is a limit to the reuse of the foundry sand because deposits on the sand remain.
In addition, the flow mold using these organic / inorganic binders has a problem that the disintegration of the mold is poor, and particularly when cement is used, there are many problems.
Further, there is a problem that gas generation due to thermal decomposition during pouring deteriorates the working environment.
[0006]
[Problems to be solved by the invention]
And for the surfactant used in the fluid mold,
In the case of the fluid molding method in which an organic / inorganic binder is added as a binder, the stability of bubbles generated by entrained air generated during kneading is good, so that a water reducing effect called an AE water reducing agent is used. In addition, a type of surfactant that entrains fine bubbles during kneading is used.
[0007]
However, the amount of added water is small, and in a freezing mold using only water, the kinematic viscosity of bubbles caused by entrained air generated at the time of kneading is low, so that the AE water reducing agent is quickly defoamed, and molding sand is cast into a molding flask. Immediately after pouring, defoaming is started, and there is a problem that the casting sand does not reach the details of the model and a drop of the filled sand occurs extremely, for example, there is a problem that a cavity is formed at a lower portion of the flange portion.
[0008]
By the way, foam is generated by manual and mechanical energy, and the molding sand that has flowed is caused to flow around the model, and the molding is performed.However, there are effects of caking, drag, fluidity and moisture in this molding. Due to the high fluidity, a small amount of water and binder is required, and a uniform mold strength structure can be formed.
[0009]
The present invention is to increase the bubbles generated by entrained air at the time of kneading by adding an appropriate additive to the molding sand used for the freezing mold to which a predetermined amount of water is added using the above-mentioned conventional silica sand as an aggregate. The object of the present invention is to provide a molding method of a frozen mold that maintains a generated foam in a stable state, forms a fluidized sand that enables fluidization, and freezes a fluidized mold formed by using the fluidized sand. Things.
[0010]
[Means for Solving the Problems]
Then, the molding method of the frozen mold of the present invention,
In a method of forming a frozen mold, a mold obtained by kneading and molding a molding sand obtained by adding 2 to 12% by weight of water to silica sand to form a frozen mold is set by freezing.
In order to fluidize the foundry sand and to ensure that the fluidized foundry sand is filled around the model to form a fluidized mold, a high foaming surfactant of 0.05 to 3% by weight based on the silica sand is used. Is added and kneaded, and fluidized sand, which contains foam generated by kneading and flows, is poured around the model to be molded, and the molded fluid mold is frozen.
[0011]
The method for molding a frozen mold of the present invention provides fluidity and moldability to a raw sand mold material that has been conventionally used, and also improves the disintegration which is a defect found in a hardened mold and improves the sand recovery rate. The present invention provides a property of improving a working environment in which no gas or the like is generated, and enables formation of a fluid mold.
[0012]
That is, 0.05 to 3% by weight of a surfactant having a high foaming property is added to the molding sand obtained by mixing 1 to 12% by weight of water with respect to the conventional silica sand, and entrained air is added when kneading. By generating fine foam generated by the above, liquid sand is formed, and when the liquid sand is poured into the casting flask, it is surely and uniformly filled to all corners around the model to form a fluid mold. In this case, the formed mold is frozen to form a frozen mold.
[0013]
By using the above-mentioned high foaming surfactant, a combination of a fluid mold and a freezing mold using water enables molding of a mold having high disintegrability and recyclable molding sand, and also hardens. Molds can be molded under a good working environment without the generation of gas, odor and smoke seen in the mold, and it is also possible to mold models with complicated sanding with conventional hands and machines. .
[0014]
Further, the surfactant is preferably an anionic surfactant, and more preferably a sulfosuccinate.
[0015]
The above invention describes the composition of a high foaming surfactant prepared for the formation of fluidized sand used in the method of molding a frozen mold of the present invention, and the surfactant used is an anionic surfactant. Preferably, a tallow amide succinate is used, and is the most suitable foam stabilizer obtained by the inventors of the present invention.
[0016]
The liquid sand containing foam used for the freezing mold is prepared by adding 0.01 to 3% by weight of a gas generating agent made of an organic substance having an NCO group to the silica sand, and reacting with water to produce CO _2. It is preferable to generate gas to absorb volume shrinkage due to defoaming of the fluidized sand containing the foam.
[0017]
In the molding method of the freezing mold by using the surfactant of the present invention, especially the tallow amide succinate, bubbles contained in the fluidized sand are stabilized, defoaming is less likely to occur, and sandfall is reduced. In other words, if freezing is terminated immediately after molding and foaming disappears immediately before molding, there is no problem because sand does not fall, but when freezing over time, it is gradually The sand has fallen and is not perfect.
The present invention has been made to completely solve the problem of falling sand, and is an organic compound having an NCO group, for example, polymethylene polyphenyl polyisocyanate added and used as a gas generating agent. ＮN ＝ C ＝ O ”, an organic substance having an NCO group such as polymethylene polyphenyl polyisocyanate is added, reacts with water to generate CO ₂ gas, and generates bubbles substantially equivalent to disappearing bubbles. The volume shrinkage caused by the defoaming is absorbed, and the effect of the defoaming is also absorbed when freezing is performed over a long time.
[0018]
It is preferable that the surfactant used in the method for forming a frozen mold of the present invention is obtained by mixing an anionic surfactant with an AE water reducing agent.
[0019]
The above-mentioned invention is a method of forming a freezing mold of the frozen mold according to the present invention, wherein a high-bubble anionic surfactant used for forming a fluidized sand is partially mixed with an AE water reducing agent which is a kind of surfactant. Is described.
That is, the AE water reducing agent enables water to be reduced without impairing workability in mixing the concrete, thereby improving strength, and at the time of kneading, utilizing the property of entraining air as fine bubbles in the concrete. It states that some may be substituted.
[0020]
Further, it is preferable that the surfactant used in the method of forming a frozen mold of the present invention is added in an amount of 0.05 to 3.0% by weight based on silica sand.
[0021]
In addition, the molding sand used in the method of molding a frozen mold of the present invention is preferably mainly composed of recovered sand or recycled sand for the purpose of reuse.
[0022]
As described above, the fluid mold used for molding the frozen mold of the present invention is rich in disintegration, sand can be collected, and an energy-saving circulating casting process can be formed.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail using embodiments shown in the drawings. The embodiment shown in FIG. 1 includes a kneading step 11 including water 10, a molding step 12 of a fluid mold, a freezing step 13 of a freezing mold, a coating step 14, a casting step 15, and a sand reusing step. In the flowchart of the energy-saving recycling casting system comprising the step 16 and using the water from the water 10, the energy-saving recycling casting system enables a more efficient energy-saving cycle for the first time by using the molding process 12 of the fluidized mold. It was done.
[0024]
As described above, the flow chart of the casting system shows that the water 10 and the sulfosuccinate tallow amide-based surfactant 10a and the organic substance 10b having an NCO group are added, and the sand (silica sand) collected and cooled in the former stage is kneaded. A kneading step 11, a shaping processing step 12 for making a fluidized mold from the kneaded molding sand, a freezing mold freezing step 13 for freezing the shaped mold, and a coating processing step 14 for coating the frozen mold. A closed cycle is formed by a casting process step 15 of casting with a frozen mold that has been subjected to a coating process, and a sand reusing process step 16 of reusing sand from the mold after casting.
[0025]
In the casting processing step 15, the frozen mold formed in the previous stage is subjected to mold matching in a mold matching step 15a, and the molten metal is passed through the molten metal step 17 in a mold pouring step 15b. The high-temperature hot water in the mold is solidified through a solidification step 15c, the mold is separated in a mold separation step 15d, and a required cast product is obtained through a finishing step 15e.
On the other hand, sand (silica sand) is recovered from the mold collapsed in the separating step 15d in the sand recovery step 16a, and the sand recovered in the sand cooling step 16b is cooled to about 40 ° C. and returned to the kneading step 11. In this way, the process of recycling silica sand is formed. The returned silica sand is again subjected to the addition of the water 10, the sulfosuccinate tallow amide-based surfactant 10 a, and the organic substance 10 b having an NCO group in the kneading step 11, and the fluid mold forming processing step 12 in the next step Circulates to
[0026]
That is, in the freezing mold freezing step 13 according to the above embodiment, the freezing processing is performed on the fluidized mold 12b obtained in the preceding fluidized mold forming step 12. As shown in the figure, the fluidized mold 12b is formed by adding fluidized sand 12a necessary for the molding between silica sand (sand obtained by the sand reuse process 16) and the water 10 in the fluidized mold forming process 12. During the kneading in the kneading step 11, the addition of the sulfosuccinate tallow amide-based surfactant 10a enables the formation of the fluidized sand 12a having fluidity and moldability, and the formation of the fluidized sand 12a has a complicated shape. This enables the molding of the fluid mold 12b that can cope with the above.
By giving the fluidity and moldability to the fluidized sand 12a comprising the sand, water and surfactant 10a, the foundry sand uses a minimum amount of water and is complicated by sanding with a minimum amount of mechanical energy. It is possible to form a space having the same shape with respect to the shape, and to form a mold with uniform and high mold strength.
[0027]
The addition amount of the sulfosuccinate tallow amide-based surfactant 10a is preferably 0.05 to 3% by weight, more preferably 0.1 to 0.3% by weight, based on silica sand.
[0028]
The above-mentioned freezing process 13 of the fluid mold 12b gives mold strength necessary for casting,
In addition, the coating mold processing step 14 provides a high-temperature strength corresponding to high-temperature pouring to the low-temperature mold to enable high-efficiency casting, and enables the formation of a completely recycle-circulation-type casting system by using only water as the binder.
[0029]
In addition, the addition of the organic substance 10b having an NCO group in the kneading step 11 causes the sedimentation of the sand caused by the defoaming of the entrained air bubbles in the fluidized sand that occurs when the freezing step 13 of the freezing mold is performed for a long time. A member that reacts with water to generate CO ₂ gas for absorption is attached.
[0030]
The addition amount of the organic substance 10b having an NCO group is preferably 0.01 to 3% by weight based on silica sand.
[0031]
【Example】
Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to only these examples.
FIG. 2A is a diagram illustrating a state of sand filled in a flask in the case of Example 1, and FIG. 2B is a diagram illustrating a state of sand filled in a flask in Example 2. FIG. 2 (C) is a view showing the state of sand filled in the flask in the case of Example 3, and FIG. 3 (A) is a view showing the state of sand filled in the flask of Comparative Example 1. FIG. 3 (B) is a view showing the condition of sand filled in the casting flask of Comparative Example 2, and FIG. 3 (C) is a drawing of the casting sand of the conventional green sand mold of Comparative Example 3 into the casting flask. It is a figure showing the situation of the sand at the time of putting.
[0032]
[Example 1]
Surfactant: sulfosuccinate tallowamide surfactant 0.2% by weight
Gas generating agent: 0.1% by weight of polymethylene polyphenyl polyisocyanate
Moisture: 3.5% by weight
In this case, as shown in FIG. 2 (A), when a gas generating agent was used in combination with the sulfosuccinate tallowamide surfactant, sand did not drop even after 3 hours or more.
In addition, the fluidity was good and the filling rate of the sand was also good.
[0033]
[Example 2]
Surfactant; sulfosuccinate tallowamide surfactant 0.1% by weight and AE water reducing agent 0.1% by weight
Gas generating agent: 0.1% by weight of polymethylene polyphenyl polyisocyanate
Moisture: 3.5% by weight
In this case, as shown in FIG. 2 (B), there was no problem in fluidity when the sulfosuccinate tallowamide-based surfactant and the AE water reducing agent were mixed.
This indicates that if a sulfosuccinate tallowamide-based surfactant is added to some extent, another surfactant can be used instead.
[0034]
[Example 3]
Surfactant; sulfosuccinate tallowamide surfactant 0.2% by weight
Gas generating agent; no moisture; 3.5% by weight
In this case, as shown in FIG. 2 (C), only the sulfosuccinate tallowamide-based surfactant was used, and the polymethylene polyphenyl polyisocyanate was not added. , And the sand gradually filled tends to settle. However, only the sand on the upper surface drops due to the hot water effect of the sand, and the lower part of the lower flange portion is sufficiently filled with the sand.
In the actual work, the liquid sand is often filled and placed higher than the model, so that it is often unnecessary to add the polymethylene polyphenyl polyisocyanate.
[0035]
[Comparative Example 1]
Surfactant; AE water reducing agent 0.4%
Gas generating agent: 0.1% by weight of polymethylene polyphenyl polyisocyanate
Moisture: 3.5% by weight
In this case, as shown in FIG. 3 (A), a polymethylene polyphenyl polyisocyanate as a gas generating agent was used for sand fluidized only with the AE water reducing agent. It is shown that the defoaming of the sand is fast, and the defoaming cannot be absorbed even if polymethylene polyphenyl polyisocyanate is added.
This is considered to be due to the effect of the surfactant on the kinematic viscosity of the foam, and when flowing only with the AE water reducing agent, the defoaming takes precedence. As a result, a gap-like space is formed below the lower flange. You.
[0036]
[Comparative Example 2]
Surfactant; sulfosuccinate tallowamide surfactant 0.2% by weight
Gas generating agent; CaO 0.3% by weight Added water; 3.5% by weight
In this case, as shown in FIG. 3 (B), a case where calcium oxide (CaO) which generates gas by reacting with water is added to a sulfosuccinate tallow amide-based surfactant and a gas generating agent. Was not effective in preventing the generated gas from passing through the gaps in the sand or preventing the falling of the sand. It is considered that there is no effect unless the substance is a liquid substance that can be mixed with a surfactant and reacts with water.
[0037]
[Comparative Example 3]
Surfactant; no gas generating agent; no moisture; 3.5% by weight
In this case, the casting sand of the conventional green sand mold is prepared, and as shown in FIG. 3 (C), a part with insufficient filling is located at the lower corner of the lower flange where the hand does not enter the lower part. I was seen.
[0038]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention which combined the freezing mold molding method with the fluid mold by liquid sand, while making mold molding with respect to a complicated model (product) possible, recycling of sand, high disintegration, favorable work environment, etc. Thereby, a low-cost circulation-type casting system that does not generate high-efficiency waste can be formed.
In addition, the configuration in which the surfactant of the fluid mold is mainly a sulfosuccinate tallow amide-based surfactant enables stable and uniform generation of fine bubbles due to entrained air, and suppresses the generation of defoaming, and is high. Fluidity, moldability and uniformity can be given to the molding sand.
Further, by using an organic compound having an NCO group in the sand, sedimentation of the sand in the flask can be prevented even when the sand is left for a long time.
In addition, since water is used as the binder, a mold molding method that is friendly to the global environment and that is friendly to the working environment, freeing the worker from sanding work can be obtained.
[Brief description of the drawings]
FIG. 1 is a flowchart of an energy-saving recycling casting system using a fluidized mold according to the present invention.
FIG. 2A is a diagram showing a state of sand filled in a flask in the case of Example 1, and FIG. 2B is a diagram showing a state of sand filled in a flask in Example 2. (C) is a diagram showing the situation of sand filled in the flask in the case of Example 3.
3 (A) is a diagram showing a state of sand filled in a flask of Comparative Example 1; FIG. 3 (B) is a diagram showing a state of sand filled in a flask of Comparative Example 2; () Is a view showing the state of sand when the casting sand of the conventional green sand mold of Comparative Example 3 was handed into a casting flask.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Water 10a Sulfosuccinate tallowamide surfactant 10b Organic substance having NCO 11 Kneading process 12 Molding process of fluid mold 12a Fluid sand 12b Fluid mold 13 Freezing process of frozen mold

Claims (6)

In a method of forming a frozen mold, a mold obtained by kneading and molding a molding sand obtained by adding 2 to 12% by weight of water to silica sand to form a frozen mold is set by freezing.
In order to fluidize the foundry sand and to ensure that the fluidized foundry sand is filled around the model to form a fluidized mold, a high foaming surfactant of 0.05 to 3% by weight based on the silica sand is used. Is added and kneaded, and flowing sand, which contains foams generated by kneading and flows, is poured around the model to form a mold, and the formed fluid mold is frozen. The method according to claim 1, wherein the surfactant is preferably an anionic surfactant, and more preferably a sulfosuccinate. The fluid sand containing the foam is prepared by adding a gas generating agent made of an organic substance having an NCO group to the silica sand in an amount of 0.01 to 3% by weight, and reacting with water to generate CO ₂ gas. 2. The method according to claim 1, wherein the volumetric shrinkage caused by the defoaming of the fluidized sand is absorbed. The method of claim 1, wherein the surfactant comprises mixing an AE water reducing agent with an anionic surfactant. The method of claim 1, wherein the surfactant is added in an amount of preferably 0.05 to 3.0% by weight based on silica sand. The method according to claim 1, wherein the foundry sand is mainly composed of recovered sand or recycled sand intended for reuse.

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