JP6572933B2 - Casting core and manufacturing method thereof - Google Patents

Description

  The present invention relates to a casting core and a method for manufacturing the same.

  Conventionally, a casting core formed by a molding method such as a shell mold method, a cold box method, or a hot box method is known. The core for casting by the molding method has an aggregate made of silica sand or mullite artificial sand and an organic binder made of phenol resin, furan resin or the like.

  In addition, for example, Patent Document 1 describes a casting core formed by drying an aqueous solution containing mullite artificial sand and an inorganic binder such as magnesium sulfate.

JP 2006-61948 A

  However, the prior art has problems in the following points. That is, a casting core using an organic binder generates decomposition gas caused by the organic binder during casting. In addition, in the casting core using the organic binder, the organic binder remains after casting. Therefore, vibration and heat treatment are separately required to collapse and take out the core.

  Moreover, the casting core using magnesium sulfate as the binder component is inferior in strength. This is due to the following reason. Magnesium sulfate reacts with moisture in the atmosphere to form a hydrate, which becomes heptahydrate at room temperature, monohydrate at 70 ° C. or higher, and anhydrous at 200 ° C. or higher, causing a volume change. For this reason, in a casting core using magnesium sulfate as a binder component, part of the binder bond is self-collapsed and the strength is reduced during casting when temperature and humidity change.

  The present invention has been made in view of such a problem, and provides a casting core capable of ensuring both strength during casting and ease of collapse after casting, and a method for producing the casting core. It is something to try.

One aspect of the present invention is a glassy aggregate (2) mainly composed of silicon dioxide,
Inorganic binder containing sodium chloride , interspersed with the aggregates in a state where the aggregate surfaces are scattered so that the surfaces of the aggregates are exposed and a gap is left between the aggregates. The casting core (1) is composed of (3).

Another aspect of the present invention is a method for producing the above casting core,
Preparing a kneaded product (6) comprising a polar solvent (5), a vitreous aggregate (2) mainly composed of silicon dioxide, and an inorganic binder (3) containing sodium chloride;
Pour the kneaded product into a mold,
In the method for producing a casting core, the kneaded product is dried and molded in the mold.

  The casting core combines a glassy aggregate mainly composed of silicon dioxide and an inorganic binder containing sodium chloride. Therefore, the above-described casting core has a small change in strength due to temperature, and can ensure strength even when exposed to high temperatures during casting. Moreover, since the inorganic core is water-soluble, the casting core can be dissolved in water, and the core can be easily collapsed after casting.

  In addition, the above-described casting core does not require a large amount of energy for core molding or for core collapse after casting, and is therefore energy-saving and advantageous in cost reduction. Further, since the above-described casting core uses an inorganic binder, no harmful gas is generated at the time of core molding, casting, or the like unlike a casting core using an organic binder. Moreover, since the said casting core is easy to isolate | separate an aggregate and an inorganic binder, the high temperature process, friction process, etc. for recycling of an aggregate are unnecessary, and it is excellent also in recyclability.

  According to the above method for producing a casting core, it is possible to produce the above casting core capable of ensuring both strength during casting and ease of collapse after casting.

  In addition, the code | symbol in the parenthesis described in the means to solve a claim and a subject shows the correspondence with the specific means as described in embodiment mentioned later, and limits the technical scope of this invention. It is not a thing.

3 is an explanatory view schematically showing a microstructure of a casting core according to Embodiment 1. FIG. FIG. 3 is an explanatory view schematically showing a kneaded product used for manufacturing the casting core of the first embodiment. It is explanatory drawing which showed typically the microstructure of the core for casting of Embodiment 3. FIG. It is explanatory drawing which showed typically the core for casting of Embodiment 4, (a) is explanatory drawing of a pipe, (b) is explanatory drawing of the core for casting. It is explanatory drawing which showed typically the core at the time of casting of Embodiment 5, and the condition at the time of casting using this. It is explanatory drawing which showed typically the core for casting of Embodiment 5, and the cast product using this.

(Embodiment 1)
The casting core and the manufacturing method thereof according to Embodiment 1 will be described with reference to FIGS. As illustrated in Figure 1, casting core 1 of this embodiment, an aggregate 2, inorganic binder 3 and Ru Tona. The details will be described below.

The aggregate 2 is glassy whose main component is silicon dioxide. “Containing silicon dioxide as a main component” means that the chemical composition contains 50% by mass or more of silicon dioxide (SiO ₂ ). Since the aggregate 2 is glassy, it is amorphous.

  The aggregate 2 can be comprised from glass fiber so that it may be illustrated by FIG. According to this configuration, it is easier to improve the strength of the casting core 1 than when the aggregate 2 is composed of spherical glass particles (described later in Embodiment 2). This is considered to be because the fibrous glass fibers are entangled with each other.

  When the aggregate 2 is comprised from glass fiber, the average length of glass fiber can be 10-1000 micrometers, for example. According to this configuration, the strength of the casting core 1 can be easily improved. The average length of the glass fiber is preferably 50 μm or more, more preferably 100 μm or more, and further preferably 150 μm or more from the viewpoint of improving the strength of the casting core 1. In addition, the average length of the glass fiber is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less from the viewpoints of core moldability, core dimensional accuracy, and the like. In addition, the average length said is an average value of each measurement length of 100 glass fibers observed with a scanning electron microscope.

The aggregate 2 may be subjected to a surface treatment. Specific examples of the surface treatment include plasma treatment and coupling treatment with a silane coupling agent. According to this configuration, the strength of the casting core 1 can be further improved. In particular, when the aggregate 2 is a glass fiber, the effects of the entanglement between the glass fibers and the surface treatment are combined, and the strength of the casting core 1 can be further improved. Examples of the silane coupling agent include 3-aminopropyltrimethoxysilane ((CH ₃ O) ₃ SiC ₃ H ₆ NH ₂ ) and 3-aminopropylethoxysilane ((C ₂ H ₅ O) ₃ SiC ₃ H _6. NH ₂ ), tetramethoxysilane ((CH ₃ O) ₄ Si) and the like can be exemplified. These can be used alone or in combination of two or more. In the plasma treatment, specifically, the aggregate 2 is subjected to surface cleaning and etching in a non-reactive gas atmosphere such as He and Ar at an atmospheric temperature of 80 to 250 ° C., and a reaction such as N ₂ and O ₂ is performed. It can be carried out by a method of introducing a functional group in a reactive gas atmosphere. In addition, the coupling treatment specifically includes immersing the aggregate 2 in an aqueous solution containing 1 to 2% by mass of a silane coupling agent, and then drying at 100 to 110 ° C. for about 30 minutes to 5 hours. Can be implemented.

  The inorganic binder 3 connects the aggregates 2 to each other. The inorganic binder 3 contains at least sodium chloride.

  Content of the inorganic binder 3 can be 1-10 mass parts with respect to 100 mass parts of aggregates. According to this configuration, the balance between strength and disintegration time is excellent. When the content of the inorganic binder 3 is less than 1 part by mass, the strength improvement effect is reduced. Therefore, the content of the inorganic binder 3 is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more from the viewpoint of easily ensuring the strength. On the other hand, when the content of the inorganic binder 3 exceeds 10 parts by mass, the time required for core collapse after casting becomes longer. Therefore, the content of the inorganic binder 3 is preferably 9.5 parts by mass or less, more preferably 9 parts by mass or less, and still more preferably 8.5 parts by mass or less from the viewpoint of improving the ease of disintegration after casting. It can be.

  The inorganic binder 3 may not be sintered or may be partially sintered. The latter configuration can further improve the strength of the casting core as compared to the former configuration.

  The casting core 1 may have a structure having a contact surface with a metal having a melting point of less than 800 ° C. on the surface. According to this structure, when used for casting with a metal having a melting point of less than 800 ° C., the metal having a melting point of less than 800 ° C. contacts the surface. Even in this case, since the inorganic binder 3 is difficult to melt, the strength of the casting core 1 can be ensured.

  Examples of the metal having a melting point of less than 800 ° C. include aluminum, aluminum alloy, zinc, zinc alloy, magnesium, magnesium alloy and the like.

The casting core 1 can be manufactured as follows. Specifically, as shown in FIG. 2, a kneaded material 6 comprising a polar solvent 5, a vitreous aggregate 2 mainly composed of silicon dioxide, and an inorganic binder 3 containing sodium chloride is prepared. The kneaded product 6 is poured into a mold, and the kneaded product 6 is at least dried in the mold to be molded. Thereby, the core 1 for casting can be manufactured.

  Any polar solvent 5 can be used as long as it can disperse the aggregate 2 and can dissolve the inorganic binder 3 containing sodium chloride. Note that the portion between the aggregates 2 shown in FIG. 2 is filled with a solution in which the inorganic binder 3 is dissolved in the polar solvent 5. Specific examples of the polar solvent 5 include water and methanol. Of these, the polar solvent 5 is preferably water from the viewpoints of the solubility, handleability, cost, and the like of the inorganic binder 3.

  The drying temperature, drying time, and the like of the kneaded product 6 can be appropriately set according to the type of the polar solvent 5 so that the polar solvent 5 disappears by drying. In addition, the inorganic binder 3 precipitates between the aggregates 2 by drying, and the aggregates 2 are connected. It is considered that the connection between the aggregates 2 due to drying is due to intermolecular force, anchor effect, or the like.

(Embodiment 2)
The casting core and the manufacturing method thereof according to Embodiment 2 will be described. Of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the above-described embodiments represent the same components as those in the above-described embodiments unless otherwise indicated.

  The casting core 1 and its manufacturing method of the present embodiment are different from the casting core 1 of Embodiment 1 and its manufacturing method in that the inorganic binder 3 further contains potassium chloride. Moreover, in the manufacturing method of the casting core 1 of this embodiment, in molding the kneaded product 6, the kneaded product 6 is dried and the inorganic binder 3 is partially sintered. This is different from the manufacturing method of the core 1.

  When the inorganic binder 3 further contains potassium chloride in addition to sodium chloride, the inorganic binder 3 can be partially sintered by firing, and the inorganic binder 3 is not partially sintered. As compared with the case, it is possible to obtain the casting core 1 having high strength. That is, in this case, since the bonding force between the inorganic binders 3 is improved, it is possible to further improve the strength while ensuring the ease of collapse of the resulting casting core 1.

  The content of potassium chloride in the inorganic binder 3 can be 3 to 15 parts by mass with respect to 100 parts by mass of sodium chloride. According to this configuration, the effect of improving the strength can be ensured. When the content of potassium chloride is less than 3 parts by mass, the effect of addition becomes small. Therefore, the content of potassium chloride is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and further preferably 6 parts by mass or more from the viewpoint of improving the strength. On the other hand, when the content of potassium chloride exceeds 15 parts by mass, the strength tends to decrease. Therefore, the content of potassium chloride is preferably 14 parts by mass or less, more preferably 12 parts by mass or less, and further preferably 10 parts by mass or less from the viewpoint of balance between strength and ease of sintering. it can.

  In order to partially sinter the inorganic binder 3, the kneaded material 6 may be dried and fired. Firing conditions can be, for example, a firing time of 220 ° C. to 300 ° C. and a firing time of 1 to 30 minutes.

  Other configurations and operational effects are the same as those of the first embodiment.

(Embodiment 3)
The casting core and the manufacturing method thereof according to Embodiment 3 will be described with reference to FIG.

  The casting core 1 and its manufacturing method of the present embodiment are different from the casting core 1 of Embodiment 1 and its manufacturing method in that the aggregate 2 is made of spherical glass particles. According to this configuration, compared to the case where the aggregate 2 is made of glass fiber (described above in the first embodiment), the fluidity during core molding and the flow of the aggregate 2 when the core collapses after casting. Excellent in properties. Therefore, the casting core 1 excellent in the formability of a thin shape and the take-out property after collapse can be obtained.

  When the aggregate 2 is composed of spherical glass particles, the average particle diameter of the spherical glass particles can be, for example, 10 to 150 μm. According to this structure, it becomes easy to make the said effect reliable. In addition, according to this configuration, there are advantages that high strength is obtained, dimensional accuracy is good, spherical glass particles do not easily fly in the atmosphere, and handling properties are good.

  The average particle diameter of the spherical glass particles is preferably 30 μm or more, more preferably 40 μm or more, and further preferably 50 μm or more, from the viewpoint of improving the take-out property after collapse. The average particle size of the spherical glass particles is preferably 130 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less, from the viewpoints of dimensional accuracy, surface roughness, and the like. The average particle diameter mentioned above is the particle diameter (diameter) d50 when the volume-based cumulative frequency distribution measured by the laser diffraction / scattering method shows 50%.

  Other configurations and operational effects are the same as those of the first embodiment.

(Embodiment 4)
A casting core with a pipe according to the fourth embodiment will be described with reference to FIG. As illustrated in FIG. 4, the casting core 1 with a pipe of the present embodiment includes a core body portion 10 that consists from casting core 1 of the first embodiment, it has a pipe 4 The

  Specifically, the pipe 4 includes an embedded portion 41 inserted into the core body portion 10 and a grip portion 42 exposed from the core body portion 10.

According to this configuration, when the polar solvent 5 such as water is supplied into the pipe 4 from the end of the pipe 4 on the gripping portion 42 side when the core is collapsed after casting, the polar solvent 5 passes through the pipe 4 and the It is supplied to the inside of the child main body 10. For this reason, it is possible to promote disintegration by the polar solvent 5 not only from the outside of the core but also from the inside of the core. Therefore, a casting core 1 with a pipe that is more easily disintegrated is obtained. Moreover, according to this structure, it becomes possible to hold | grip the holding part 42 exposed outside from the core main-body part 10, and to set the casting core 1 with a pipe to a casting die. Therefore, the casting core 1 with a pipe excellent in adaptability to automation and the like can be obtained.

  In this embodiment, as shown in FIG. 4A, when the embedded portion 41 has one or more through holes 411 on the side surface, not only the tip portion of the pipe 4 but also the embedded portion. The polar solvent 5 such as water can be ejected also from the side surface 41. Therefore, in this case, the core collapsibility after casting can be further improved. Further, there is an advantage that it becomes easy to uniformly cool the casting with the polar solvent 5.

The pipe 4 can be made of, for example, a metal (including an alloy) such as stainless steel, copper, a copper alloy, aluminum, or an aluminum alloy. The surface of the pipe 4 may be subjected to uneven processing or hydrophilic surface treatment. According to this structure, it becomes possible to improve the adhesiveness of the core main-body part 10 and the pipe 4 in the casting core 1 with a pipe.

  In the casting core 1 of the present embodiment, the pipe 4 is connected to the core body 10 so that the grip portion 42 does not enter the cavity of the casting mold from the viewpoint of improving the ease of taking out the core after casting. It is preferable that it is held.

  Other configurations and operational effects are the same as those of the first embodiment.

(Embodiment 5)
A casting core with a pipe according to the fifth embodiment will be described with reference to FIGS. 5 and 6. As illustrated in FIGS. 5 and 6, in the casting core 1 with a pipe according to the present embodiment, the core body 10 is provided at the core root 11 and the tip of the core root 11. It has a core diameter-enlarged portion 12 having a diameter larger than that of the core root portion 11. The buried portion 41 of the pipe 4 includes a branch portion 412 that extends along the core diameter-expanded portion 12. In the present embodiment, the branching portion 412 is specifically provided at the distal end portion of the embedded portion 41. The branching portion 412 is branched into a forked shape along the diameter increasing direction of the core expanding portion 12. In FIG. 5, reference numeral 9 denotes a mold including an upper mold 91 and a lower mold 92. Moreover, the code | symbol PL is a metal mold | die division surface. Reference numeral 930 is a molten metal. Moreover, in FIG. 6, the code | symbol 93 is the casting used as a product.

According to this configuration, as shown by an arrow Y in FIG. 6, the polar solvent 5 such as water is rapidly supplied to the enlarged diameter portion 12 through the branch portion 412 of the pipe 4 in the main body of the pipe 4. be able to. Therefore, according to this structure, even when the core 1 for casting with a pipe has the enlarged diameter part 12, it is easy to collapse a core after casting, and it is advantageous for cooling the casting 93 rapidly. . Moreover, according to this structure, it becomes possible to make the casting 93 into the undercut shape which cannot be shape | molded with a metal mold | die.

As shown in FIG. 5, the casting core 1 with a pipe may satisfy the following relationship.
Diameter C of the core expanded portion 12> Diameter B of the core root portion 11> Diameter A of the branch portion 412 of the pipe 4
According to this configuration, in addition to the above-described effects, a casting core 1 with a pipe can be obtained in which the pipe 4 can be easily taken out from the casting 93 after the core collapses.

  Other configurations and operational effects are the same as those of the fourth embodiment.

(Experimental example)
A simple mold capable of forming a core test piece of 10 mm × 10 mm × 50 mm was prepared. The mold is provided with a heater and a thermocouple so that the temperature can be adjusted. In addition, the mold can be adjusted in the pressing force during molding using a simple press machine.

The following aggregates were prepared.
・ Glass fibers mainly composed of silicon dioxide (average length: 100 μm)
The glass fiber has a chemical composition of mass%, SiO ₂ : 53%, Al ₂ O ₃ : 15%, CaO: 21%, MgO: 2%, B ₂ O ₃ : 8%, Na ₂ O + K. ₂ O: 0.3%, ig. Loss: 0.7% was used.
・ The above-mentioned glass fiber subjected to the above-mentioned plasma treatment. ・ The above-mentioned glass fiber subjected to the above-mentioned coupling treatment with the silane coupling agent. ・ Mullite artificial sand (average particle size: 100 μm)

The following inorganic binders were prepared.
・ Sodium chloride (NaCl)
・ Potassium chloride (KCl)
Magnesium sulfate (MgSO ₄ )

  Each kneaded material was prepared by kneading a predetermined aggregate, an inorganic binder, and a polar solvent with the composition shown in Table 1 below.

  The prepared predetermined kneaded material was poured into a simple mold, and the kneaded material was dried in the mold. Moreover, about one part, after drying, it baked on the conditions for 30 minutes at 220 degreeC. This produced the core for casting of each sample shown in below-mentioned Table 2. The mold temperature was 120 ° C., and the pressure applied during molding was 8 MPa.

  The four-point bending strength was measured for each obtained casting core. The 4-point bending strength is an average value when n number = 3. In addition, when a casting core is used for actual casting, the casting core is used after the molten metal is poured after the molten metal is poured after being set in the mold. Exposed to high temperatures. Therefore, assuming this casting situation, not only the room temperature but also the four-point bending strength (200 ° C.) of the casting core when the temperature was raised was measured.

  Moreover, about each obtained core for casting, the melt | dissolution time with water was measured. These results are summarized in Table 2.

  According to Tables 1 and 2, the following can be understood. Since the samples f and h used an inorganic binder not containing sodium chloride, the strength could not be improved.

  Since the sample i uses crystalline artificial sand and magnesium sulfate as an inorganic binder, the strength greatly decreases at high temperatures. This is because magnesium sulfate reacts with moisture in the atmosphere to form a hydrate, which becomes heptahydrate at room temperature, monohydrate at 70 ° C or higher, and anhydrous at 200 ° C or higher, resulting in a volume change. This is thought to be because part of the binder bond self-collapsed and the strength decreased.

  Sample j is fired based on sample i. However, the strength of the sample j was lowered by being heated to a high temperature by firing.

  Sample k is a combination of crystalline artificial sand and an inorganic binder containing sodium chloride. Sample l is sodium chloride itself. According to these samples k and l, sodium chloride itself is not effective, but a combination of a vitreous aggregate mainly composed of silicon dioxide and an inorganic binder containing sodium chloride, as described later, It can be seen that the strength is improved.

  According to the samples l, m, and n, it can be seen that the strength is improved when the inorganic binder contains potassium chloride in addition to sodium chloride. Moreover, it turns out that an inorganic binder is partially sintered by baking and intensity | strength improves further. Moreover, it can be said that the inorganic binder alone has poor solubility in water, and it takes time to take out after casting.

  On the other hand, samples a to e, b2, and b3 are composed of a combination of a vitreous aggregate containing silicon dioxide as a main component and an inorganic binder containing sodium chloride. Therefore, it was confirmed that the strength change due to the temperature change during casting was small and the strength could be secured. Moreover, it was confirmed that all of the samples a to e, b2, and b3 are excellent in solubility in water and easily disintegrate.

  Moreover, when the samples b and a were compared, when the content of the inorganic binder decreased, the strength tended to decrease.

  In addition, from the results of samples c and b, it can be seen that when the inorganic binder does not contain potassium chloride, the strength is comparable even when fired.

  Moreover, from the results of samples d and b, when the inorganic binder contained potassium chloride in addition to sodium chloride, the strength was slightly improved even without firing. From the results of samples e and b, it was confirmed that when the inorganic binder contains potassium chloride in addition to sodium chloride, the strength improvement effect is increased by firing. This is because the inorganic binder was partially sintered by firing.

  In addition, according to samples o and p, when an inorganic binder having an excessive amount of potassium chloride relative to sodium chloride is used, the strength is improved as compared with the case where an inorganic binder having an appropriate amount of potassium chloride relative to sodium chloride is used. There was a tendency for the effect of to decrease. When the inorganic binder contains potassium chloride, from the viewpoint of increasing the strength improvement effect, the content of potassium chloride with respect to 100 parts by mass of sodium chloride is 3 to 15 parts by mass.

  Moreover, when samples b, b2, and b3 were compared, when the content of the inorganic binder decreased, the strength decreased. It can be seen that the strength of the casting core can be further improved by using the aggregate subjected to the surface treatment. Moreover, when the aggregate 2 is glass fiber, it turns out that it becomes easy to improve the intensity | strength of the core for casting combined with the effect by entanglement by glass fiber and surface treatment.

The present invention is not limited to the above-described embodiments and experimental examples, and various modifications can be made without departing from the scope of the invention. Moreover, each structure shown by each embodiment and each experiment example can be combined arbitrarily, respectively. For example, in Embodiments 1 to 5, the aggregate 2 may include both glass fibers and spherical glass particles. In Embodiments 3 to 5, the inorganic binder 3 may further contain potassium chloride. Further, a casting core 1 embodiment 2 may be a casting core with a pipe and a pipe 4 described in the fourth and fifth embodiments. In Embodiments 2 and 3, the aggregate may be subjected to a surface treatment such as a plasma treatment or a coupling treatment. Moreover, in Embodiments 1-5, the artificial sand etc. to which the said surface treatment was given can also be used as an aggregate.

1 Core for casting 2 Aggregate 3 Inorganic binder 5 Polar solvent 6 Kneaded material

Claims (16)

Vitreous aggregate (2) mainly composed of silicon dioxide;
Inorganic binder containing sodium chloride , interspersed with the aggregates in a state where the aggregate surfaces are scattered so that the surfaces of the aggregates are exposed and a gap is left between the aggregates. A casting core (1) consisting of (3).   The core for casting of Claim 1 whose content of the said inorganic binder is 1-10 mass parts with respect to 100 mass parts of said aggregates.   The core for casting according to claim 1 or 2, wherein the inorganic binder further contains potassium chloride.   The casting core according to claim 3, wherein the inorganic binder contains 3 to 15 parts by mass of the potassium chloride with respect to 100 parts by mass of the sodium chloride.   The casting core according to claim 1, wherein the inorganic binder is partially sintered.   The casting core according to any one of claims 1 to 5, wherein the aggregate is made of glass fiber.   The casting core according to any one of claims 1 to 5, wherein the aggregate is made of spherical glass particles.   The casting core according to any one of claims 1 to 5, wherein the aggregate is composed of glass fibers and spherical glass particles.   The casting core according to claim 1, wherein the casting core has a contact surface with a metal having a melting point of less than 800 ° C. on the surface.   The casting core according to claim 9, wherein the metal is aluminum, an aluminum alloy, zinc, a zinc alloy, magnesium, or a magnesium alloy. It has a core body part (10) comprised from the core for casting according to any one of claims 1 to 10, and a pipe (4),
The said pipe is a casting core with a pipe provided with the embedding part (41) inserted in the said core main-body part (10), and the holding part (42) exposed from the said core main-body part. The core body portion includes a core root portion (11) and a core widening portion (12) having a diameter larger than that of the core root portion, provided at a tip portion of the core root portion. Have
12. The casting core with a pipe according to claim 11, wherein the embedded portion of the pipe includes a branching portion (412) along the core enlarged diameter portion. The core for casting with a pipe according to claim 12, wherein the diameter of the core enlarged portion> the diameter of the core root portion> the diameter of the branch portion of the pipe is satisfied. A method for producing the casting core according to claim 1, comprising:
Preparing a kneaded product (6) comprising a polar solvent (5), a vitreous aggregate (2) mainly composed of silicon dioxide, and an inorganic binder (3) containing sodium chloride;
Pour the kneaded product into a mold,
A method for producing a casting core, wherein the kneaded product is dried and molded in the mold. The method for producing a casting core according to claim 14 , wherein the inorganic binder further contains potassium chloride. The method for producing a casting core according to claim 14 or 15 , wherein in molding the kneaded product, the kneaded product is dried and the inorganic binder is partially sintered.

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