JP3640248B2 - Freezing mold molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a frozen mold in which a casting mold mixed with a predetermined amount of water is filled around a model built in a mold to form a mold, and the obtained mold is cured by freezing to obtain a frozen mold. In the molding method of
In order to give fluidity to the foundry sand containing the predetermined moisture filling the periphery of the model, a predetermined surfactant is added, and 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 in which a mold is prepared and the formed fluid mold is cured by freezing to obtain a frozen mold.
[0002]
[Prior art]
A method for producing a frozen mold in which a predetermined amount of water is mixed with the foundry sand and a mold formed by using the mixed foundry sand is frozen to produce a frozen mold is disclosed in, for example, Japanese Patent Publication No. 56-30107. ing.
According to the invention disclosed in the publication, liquefied gas such as nitrogen or dry ice is used as the refrigerant used for freezing.
Japanese Patent Laid-Open No. 11-138235 discloses a proposal relating to a method of freezing by passing low-temperature air using a refrigerator through a mold.
[0003]
By the way, for the fluid mold, cinnabar is used as an aggregate, and a self-hardening mold using an inorganic binder such as phosphoric acid or sodium aluminate as a binder for binder, water glass or cement, Similarly, fluid mold making methods are used for self-hardening molds and gas-curing molds that use an organic binder such as a resin component such as furan resin, phenol resin, or urethane resin as a binder.
In other words, in the cement flow casting method, cement, water and a surfactant are added to dredged sand, and the mixture is kneaded with a mixer to form fluidized sand and poured into a casting frame.
In the case of a water glass-based self-hardening mold, a method of adding water glass and a surfactant to dredged sand, kneading with a mixer to form fluidized sand, and pouring into a casting frame is employed.
[0004]
On the other hand, in the case of conventional molds used for freezing molds that are not flow molds, molds for products with complicated shapes that cannot be sanded by hand or machine require complicated work via cores or split molds. Although it is necessary, if a fluid mold is possible, a mold for a complex product can be easily formed by pouring fluid sand.
However, in the case of the fluid mold molding method used for self-hardening molds and gas curing molds using the above organic binders, it is easy to mold molds for complex models by simply pouring fluid sand into the casting frame as described above. However, the following problems are built in.
[0005]
That is, in the fluid mold making method using an inorganic binder such as 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 once hardened, and much labor is required for reuse.
Moreover, even when a fluid mold is made with organic vines such as furan and phenol and water, there is a limit to the reuse of foundry sand because the deposits remain on the sand.
Further, fluid molds using these organic / inorganic binders have a problem that the mold disintegration is poor, and there are many problems especially when cement is used.
In addition, gas generation due to thermal decomposition during pouring has a problem of deteriorating the working environment.
[0006]
[Problems to be solved by the invention]
And about the surfactant used for the flow mold,
In the case of the above-described fluid mold molding method in which an organic / inorganic binder is added as a binder, the stability of foam generated by entrained air generated during kneading is good, and therefore a water reducing effect called an AE water reducing agent In addition, a kind of surfactant that entrains fine bubbles during kneading is used.
[0007]
However, in the freezing mold that uses only water and the amount of water added is small, the AE water reducing agent has a fast defoaming because of the low kinematic viscosity of entrained air generated during kneading. There is a problem that defoaming is started immediately after pouring, the cast sand that has been poured does not reach the details of the model, and the falling of the filled sand occurs extremely, for example, forming a cavity in the lower part of the flange.
[0008]
By the way, bubbles are generated by manual and mechanical energy, and the cast sand that has been made to flow is made to flow around the model, and this moldability is affected by caking, drag, fluidity and moisture. The high fluidity requires less moisture and binder, and can form a uniform type of strength structure.
[0009]
The present invention increases the foam generated by the entrained air during kneading by adding an appropriate additive to the foundry sand used in a freezing mold in which a predetermined amount of water is added using the above-mentioned conventional dredged sand as an aggregate. An object of the present invention is to provide a method for forming a frozen mold that maintains the generated bubbles in a stable state, forms fluidized sand that enables fluidization, and freezes the fluidized mold formed by using the fluidized sand. Is.
[0010]
[Means for Solving the Problems]
Therefore, the method for forming a frozen mold of the present invention is as follows.
In a molding method of a freezing mold in which a mold obtained by kneading and molding a casting sand to which 2 to 12% by weight of water is added to dredged sand is formed by freezing, a freezing mold is formed.
In order to fluidize the foundry sand and reliably fill the fluidized foundry sand around the model to form a fluid mold, 0.05 to 3% by weight of the highly foamable surfactant with respect to the dredged sand Is added and kneaded, and fluidized sand containing bubbles generated by kneading is poured into the periphery of the model to be molded, and the molded fluid mold is frozen.
[0011]
The method for molding a frozen mold according to the present invention provides fluidity and moldability to the raw sand mold material that has been used conventionally, and improves the disintegration, which is a defect found in a cured mold, and improves the sand recovery rate. It gives the characteristics of improving and improving the working environment in which no gas is generated, and enables the formation of a flow mold.
[0012]
In other words, 0.05 to 3% by weight of a surfactant having high foaming property is added to the foundry sand mixed with 1 to 12% by weight of water with respect to the conventional cinnabar, and entrained air is used for kneading. The fine sand bubbles generated by the above are generated to form fluid sand, and when the fluid sand is poured into the casting frame, it is filled surely and uniformly to the corners around the model to form a fluid mold. The formed mold is frozen to form a frozen mold.
[0013]
The use of the above highly foaming surfactant enables the molding of a mold that can be disintegrated and reuse the foundry sand by combining a fluid mold using water and a freezing mold, and is also hardened. The molds can be molded under good working conditions without the generation of gas, odor, and smoke found in the mold, and it is also possible to mold models that have complicated sanding with conventional human hands and machines. .
[0014]
Further, the surfactant, Ri A anion surfactant der, good Mashiku is of good sulfosuccinate salt.
[0015]
The above-described invention describes the composition of a highly foaming surfactant prepared for forming fluidized sand used in the molding method of a freezing mold of the present invention. The surfactant used is an anionic surfactant. The succinate beef tallow amide is preferably used, and is the optimum foam stabilizer obtained by the inventors of the present invention.
[0016]
In addition, the fluidized sand containing foam used for the freezing mold is prepared by adding 0.01 to 3% by weight of a gas generating agent composed of an organic substance having an NCO group to the dredged sand and reacting with water to produce CO _2. A configuration in which gas is generated and volume shrinkage due to defoaming of the fluid sand containing the foam is absorbed is preferable.
[0017]
In the method of forming a freezing mold by using the surfactant of the present invention, particularly succinate beef tallow amide, the bubbles contained in the fluidized sand are stabilized and the defoaming hardly occurs, and the sand falling is reduced. In other words, if you freeze immediately after molding and finish freezing before the bubbles disappear, there will be no problem with the sand falling, but if you freeze it over time, it will gradually. The situation is not perfect because of the falling sand.
The invention has been made in order to completely solve the problem of sand falling, and is an organic compound having an NCO group to which, for example, polymethylene polyphenyl polyisocyanate is added and used as a gas generating agent. ˜N═C═O ”, an organic substance having an NCO group, such as polymethylene polyphenyl polyisocyanate, reacts with water to generate CO ₂ gas, and generates bubbles substantially equivalent to the disappearing bubbles, Even when the volume shrinkage due to the defoaming is absorbed and the freezing takes time, the influence of the defoaming is absorbed.
[0018]
Moreover, it is preferable that the surfactant used in the method for forming a frozen mold of the present invention is mixed with an anionic surfactant and an AE water reducing agent.
[0019]
In the invention described above, partial mixing of an AE water reducing agent, which is a kind of surfactant, with a high-bubble anionic surfactant used for forming fluid sand of a fluid mold used for forming the frozen mold of the present invention. Is described.
In other words, the AE water reducing agent can reduce water without impairing workability in mixing concrete and improve strength, and at the time of kneading, utilizing the characteristic of entraining air as fine bubbles in the concrete. It states that some may be substituted.
[0020]
Moreover, it is preferable to add 0.05 to 3.0 weight% of the surfactant used for the method for forming a frozen mold of the present invention with respect to the sand.
[0021]
Moreover, it is preferable that the foundry sand used for the molding method of the frozen mold of the present invention is mainly recovered sand or recycled sand for reuse.
[0022]
As described above, the fluid mold used for forming the frozen mold of the present invention is rich in collapsibility, and sand can be collected, and an energy-saving circulation casting process can be formed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. In the embodiment shown in FIG. 1, the kneading step 11 including water 10, the flow mold forming process 12, the freezing mold freezing process 13, the coating process 14, the casting process 15, and the sand reuse process. The flowchart of the energy-saving recycle casting system which consists of the process 16 and uses the water by the said water | moisture 10 WHEREIN: This energy-saving recycle cast system enables a more efficient energy-saving cycle for the first time by use of the said casting process step 12 of the fluid mold. It is a thing.
[0024]
As described above, in the flowchart of the casting system, the water 10 and the sulfosuccinate beef tallow amide surfactant 10a and the organic substance 10b having an NCO group are added, and the sand recovered and cooled in the previous stage (kneaded sand) is kneaded. A kneading step 11, a molding processing step 12 for producing a fluid mold from the kneaded foundry sand, a freezing mold freezing step 13 for freezing the molded mold, and a coating processing step 14 for coating the frozen mold. Then, a closed cycle is formed by a casting processing step 15 in which casting is performed with a frozen mold subjected to coating processing, and a sand reuse processing step 16 in which sand is reused after the casting is finished.
[0025]
In the casting process 15, the frozen mold formed in the previous stage is mold-matched in the mold-matching process 15 a, hot water that has passed through the molten metal process 17 is poured into the mold that has been mold-matched in the pouring process 15 b, The high temperature hot water in the mold is solidified through the solidification step 15c, then the mold is separated in the mold separation step 15d, and then the required cast product is obtained through the finishing step 15e.
On the other hand, sand (salted sand) is collected from the mold collapsed in the separating step 15d by the sand collecting step 16a, and the sand collected by the sand cooling step 16b is cooled to about 40 ° C. and returned to the kneading step 11. The recycling process of dredged sand is formed. In the kneading step 11, the returned dredged sand is added with water 10 and sulfosuccinate beef tallow amide surfactant 10a, and an organic substance 10b having an NCO group. Circulate to.
[0026]
In other words, in the freezing mold freezing process 13 according to the above embodiment, the freezing process is performed on the fluid mold 12b obtained by the former forming process 12 of the fluid mold. As shown in the figure, the fluid mold 12b is obtained by converting the fluid sand 12a necessary for the molding between dredged sand (sand obtained by the sand reuse treatment process 16) and water 10 in the fluid mold molding process 12. When kneading in the kneading step 11, the addition of the sulfosuccinate beef tallow amide surfactant 10a enables the formation of fluid sand 12a having fluidity and moldability, and the formation of the fluid sand 12a has a complicated shape. This makes it possible to mold the flow casting mold 12b.
By providing the fluidity and moldability to the fluid sand 12a composed of the sand, water, and the surfactant 10a, the foundry sand uses a minimum amount of water and is complicated by sanding with a minimum mechanical energy. A space having the same shape can be formed with respect to the shape, and a mold having a uniform and high mold strength can be formed.
[0027]
The addition amount of the sulfosuccinate beef tallow amide surfactant 10a is 0.05 to 3% by weight, preferably 0.1 to 0.3% by weight, based on the cinnabar.
[0028]
The mold strength necessary for casting is given by the above freezing treatment step 13 of the fluid mold 12b,
In addition, the coating process 14 gives the low-temperature mold high-temperature strength corresponding to high-temperature pouring and enables high-efficiency casting, and the use of only water as the binder makes it possible to form a completely recycled circulation casting system.
[0029]
In addition, the addition of the organic substance 10b having an NCO group in the kneading step 11 causes the sedimentation of sand due to the defoaming of entrained air bubbles in the fluidized sand that occurs when the freezing treatment step 13 of the freezing mold takes 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 the NCO group is preferably 0.01 to 3% by weight with respect to the cinnabar.
[0031]
【Example】
EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples.
FIG. 2 (A) is a view showing the state of sand filled into the casting frame in the case of Example 1, and FIG. 2 (B) is a view showing the state of sand filled into the casting frame in the case of Example 2. 2C is a view showing the state of sand filled into the casting frame in the case of Example 3, and FIG. 3A is a view showing the state of sand filled into the casting frame of Comparative Example 1. FIG. 3 (B) is a diagram showing the state of sand filled in the casting frame of Comparative Example 2, and FIG. 3 (C) is a drawing of the conventional green sand casting sand of Comparative Example 3 into the casting frame. It is a figure which shows the condition of the sand at the time of putting.
[0032]
[Example 1]
Surfactant; sulfosuccinate tallow amide surfactant 0.2% by weight
Gas generant; polymethylene polyphenyl polyisocyanate 0.1% by weight
Water content: 3.5% by weight
In this case, as shown in FIG. 2 (A), when a gas generating agent was used in combination with a sulfosuccinate beef tallow amide surfactant, no sand falling was observed even after 3 hours or more.
The fluidity was also good and the sand filling rate was good.
[0033]
[Example 2]
Surfactant: sulfosuccinate beef tallow amide surfactant 0.1% by weight
And AE water reducing agent 0.1% by weight
Gas generant; polymethylene polyphenyl polyisocyanate 0.1% by weight
Water content: 3.5% by weight
In this case, as shown in FIG. 2B, there was no problem in fluidity when a sulfosuccinate beef tallow amide surfactant and an AE water reducing agent were mixed.
This indicates that other surfactants can be substituted if a sulfosuccinate beef tallow amide surfactant is added to some extent.
[0034]
[Example 3]
Surfactant; sulfosuccinate beef tallow amide surfactant 0.2% by weight
Gas generant; None moisture; 3.5 wt%
In this case, as shown in FIG. 2 (C), the flowability was sufficient when only the sulfosuccinate beef tallow amide surfactant was added and no polymethylene polyphenyl polyisocyanate was added. It shows the tendency that the sand that has been gradually filled by settling is settling. However, only the sand on the upper surface is lowered due to the hot water of the sand, and the lower portion of the lower flange portion is sufficiently filled with sand.
In actual work, since fluid sand is often filled higher than the model, polymethylene polyphenyl polyisocyanate need not be added in many cases.
[0035]
[Comparative Example 1]
Surfactant; AE water reducing agent 0.4%
Gas generant; polymethylene polyphenyl polyisocyanate 0.1% by weight
Water content: 3.5% by weight
In this case, as shown in FIG. 3 (A), when the gas generating agent polymethylene polyphenyl polyisocyanate is used for the sand fluidized only with the AE water reducing agent, the fluidization is performed only with the AE water reducing agent. It has been shown that sand is fast defoaming and cannot be absorbed even when polymethylene polyphenyl polyisocyanate is added.
This is thought to be due to the effect of the surfactant on the kinematic viscosity of the foam, and when it is made to flow only with the AE water reducing agent, defoaming takes precedence, and as a result, a gap-like space is formed under the lower flange. The
[0036]
[Comparative Example 2]
Surfactant; sulfosuccinate beef tallow amide surfactant 0.2% by weight
Gas generating agent; CaO 0.3 wt% added water; 3.5 wt%
In this case, as shown in FIG. 3 (B), when calcium oxide (CaO) that reacts with water and generates gas is added to the sulfosuccinate beef tallow amide surfactant and the gas generating agent, in this case Was not effective in preventing the sand from falling because the generated gas passed through the gaps in the sand. It is considered to be ineffective unless it is a liquid substance that can be mixed with a surfactant and does not react with water.
[0037]
[Comparative Example 3]
Surfactant; None gas generant; None moisture; 3.5 wt%
In this case, when the conventional green sand-type cast sand is prepared, as shown in FIG. 3 (C), there is an insufficiently filled portion at the lower corner of the lower flange where the hand does not enter the lower part. It was seen.
[0038]
【The invention's effect】
According to the present invention in which a freezing mold molding method is combined with a fluid mold using fluid sand, it is possible to mold a mold for a complex model (product), as well as sand recycling, high disintegration, good working environment, etc. Thus, it is possible to form a low-cost circulation casting system that does not produce highly efficient waste.
In addition, the composition mainly composed of a sulfosuccinate beef tallow amide surfactant in the flow mold surfactant enables stable and uniform generation of fine bubbles by entrained air, while suppressing the occurrence of defoaming and high Fluidity, moldability and uniformity can be imparted to foundry sand.
Further, by using an organic compound having an NCO group in the sand, sedimentation of the sand in the casting frame can be prevented even when left for a long time.
In addition, since water is used as a binder, it is possible to obtain a mold forming method that is kind to the global environment and is gentle to the work environment that frees the operator from sand-filling work.
[Brief description of the drawings]
FIG. 1 is a flowchart of an energy-saving recycling casting system using a fluid mold according to the present invention.
FIG. 2A is a view showing the state of sand filled into the casting frame in the case of Example 1, and FIG. 2B is a view showing the state of sand filled into the casting frame in the case of Example 2. (C) is a view showing the state of sand filled into the casting frame in the case of Example 3.
FIG. 3A is a view showing the state of sand filled into the casting frame of Comparative Example 1, and FIG. 3B is a view showing the state of sand filling into the casting frame of Comparative Example 2; ) Is a diagram showing the state of sand when the conventional green sand-type cast sand of Comparative Example 3 is handed into the casting frame.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Water 10a Sulfosuccinate tallow amide surfactant 10b Organic substance 11 with NCO 11 Kneading process 12 Fluid mold shaping process 12a Fluid sand 12b Fluid mold 13 Freezing mold freezing process

Claims (6)

In a molding method of a freezing mold in which a mold obtained by kneading and molding a casting sand to which 2 to 12% by weight of water is added to dredged sand is formed by freezing, a freezing mold is formed.
In order to fluidize the foundry sand and reliably fill the fluidized foundry sand around the model to form a fluid mold, 0.05 to 3% by weight of the highly foamable surfactant with respect to the dredged sand A method for forming a frozen mold, comprising: adding and kneading, flowing and flowing fluid sand containing bubbles generated by kneading around the model, and freezing the molded fluid mold. The surfactant molding method of freezing mold according to claim 1, characterized in that the A anion surfactant. In the fluid sand containing foam, 0.01 to 3% by weight of a gas generating agent composed of an organic substance having an NCO group is added to the dredged sand to generate CO ₂ gas by reaction with water, The method for forming a frozen mold according to claim 1, wherein volume shrinkage due to defoaming of fluidized sand containing water is absorbed.   The method for molding a freezing mold according to claim 1, wherein the surfactant is mixed with an anionic surfactant and an AE water reducing agent. The surfactant molding method of freezing mold according to claim 1, wherein the to addition of 0.05 to 3.0 wt% with respect to 硅 sand.   2. The method for forming a frozen mold according to claim 1, wherein the foundry sand is mainly recovered sand or recycled sand for reuse.

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