Mold molding method and mold material

Abstract

A mold molding method for molding a mold for manufacturing an iron-based casting, the method comprising: a step for preparing a kneaded sand using an artificial sand as an aggregate and a binder; a step for filling a mold with the kneaded sand; and a step for curing the kneaded sand filled in the mold.

Description

Technical Field

[0001] The invention relates to a casting mold forming method and a casting mold material. Background Art

[0002] Patent Document 1 discloses a casting mold. The casting mold is produced by bonding molded silica sand with a binder. The main component of silica sand is silicon dioxide (SiO2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2014-527915 Summary of the invention

[0006] When the casting mold described in Patent Document 1 is used to manufacture iron-based castings, metal oxides (e.g., FeO) in the melt sometimes react with silicon dioxide (SiO2) contained in silica sand, which is an aggregate of the casting mold, to generate fayalite (2FeO·SiO2). Fayalite (2FeO·SiO2) may cause sintering defects of the casting sand on the surface of the casting or cause poor filling. In order to reduce the defects, for example, it is considered to apply a mold coating on the casting mold. However, due to the increase in manufacturing processes, productivity decreases. The present disclosure provides a technology for suppressing the occurrence of defects in the molding of a casting mold for manufacturing iron-based castings without reducing productivity.

[0007] One aspect of the present disclosure relates to a casting mold shaping method, which is a method for shaping a casting mold for manufacturing iron-based castings. The method includes the following steps.

[0008] (1) A step of preparing mixed sand using artificial sand as aggregate and a binder.

[0009] (2) A step of filling a mold with kneaded sand.

[0010] (3) A step of solidifying the kneaded sand filled in the mold.

[0011] In this casting mold forming method, artificial sand is used as aggregate, so the content of silicon dioxide (SiO2) can be greatly suppressed compared with natural silica sand containing more than 90% of silicon dioxide (SiO2). Therefore, compared with the casting mold made with natural silica sand as aggregate, the casting mold made by this casting mold forming method is not easy to produce iron olivine (2FeO·SiO2). Therefore, compared with the case where natural silica sand is used as aggregate, this casting mold forming method can suppress the occurrence of casting sand sintering defects and poor filling on the surface of the casting. In addition, since iron olivine (2FeO·SiO2) is not easy to be produced, there is no need to apply a mold coating. Therefore, this casting mold forming method can suppress the occurrence of defects without reducing productivity.

[0012] In one embodiment, the artificial sand contains more than 60% alumina (Al2O3) and less than 40% silicon dioxide (SiO2), and the binder may be any one of sodium silicate and potassium silicate.

[0013] In one embodiment, the molar ratio of the binder may be 1.8 or more. In this case, the casting mold forming method can ensure the strength of the casting mold and improve the disintegration of the casting mold.

[0014] In one embodiment, the binder can be 4 parts by weight or less relative to 100 parts by weight of the aggregate. In order to ensure the strength of the mold, it is necessary to add more binder. In the case of natural silica sand as the aggregate, more than 4 parts by weight of the binder is usually added. However, when more binder is added, the disintegration of the mold becomes worse. In this mold modeling method, the aggregate is artificial sand, so that even if the addition amount of the binder is less than 4 parts by weight, the strength of the mold can be fully obtained. Therefore, this mold modeling method can both ensure the strength of the mold and improve the disintegration of the mold.

[0015] In one embodiment, the artificial sand can be manufactured by a melting method or a sintering method. The artificial sand manufactured by the melting method or the sintering method can reduce the amount of binder compared to artificial sand manufactured by other methods, so the casting molding method can reduce the manufacturing cost.

[0016] In one embodiment, the mixed sand can be solidified by a dehydration condensation reaction in the solidification step. In the case of solidification using a dehydration condensation reaction, in the filling step, the wet mixed sand can be blown and filled into a heated metal mold, or the foamed mixed sand can be injected and filled into the heated metal mold. This casting molding method can realize a foundry with less odor and a good environment. In contrast, when using ester to solidify it, an organic odor is generated, and when the metal powder is solidified by reacting with water glass, hydrogen is generated.

[0017] In one embodiment, in the step of solidification, carbon dioxide (CO2) gas can be used to solidify the mixed sand. When solidification using carbon dioxide (CO2) gas is adopted, in the step of filling, the wet mixed sand can be filled by manual filling, vibration filling, extrusion filling or blowing filling. This casting molding method can realize a foundry with less odor and good environment. On the other hand, when ester is used for solidification, an organic odor is generated, and when metal powder is reacted with water glass for solidification, hydrogen is generated.

[0018] In one embodiment, the mixed sand may be foamed mixed sand containing a surfactant. The mold forming method uses foamed mixed sand containing artificial sand as an aggregate, thereby improving the filling property of the sand and suppressing the occurrence of defects without reducing productivity.

[0019] Another aspect of the present disclosure relates to a mold material for manufacturing iron-based casting molds. The mold material includes artificial sand with an aluminum oxide (Al2O3) content of 60% or more and a silicon dioxide (SiO2) content of 40% or less as an aggregate, and any one of sodium silicate and potassium silicate as a binder. In the mold material, the silicon dioxide (SiO2) contained in the aggregate is less than 40%, and the content of silicon dioxide (SiO2) is greatly suppressed compared with natural silica sand containing more than 90% silicon dioxide (SiO2). Therefore, the mold made using the mold material is less likely to produce iron olivine (2FeO·SiO2) than the mold made using natural silica sand as the aggregate. Therefore, compared with the case where natural silica sand is used as the aggregate, the mold material can suppress the occurrence of casting sand sintering defects and poor filling on the surface of the casting. In addition, since iron olivine (2FeO·SiO2) is not easily produced, it is not necessary to apply a mold coating. Therefore, this mold material can suppress the occurrence of defects without reducing productivity.

[0020] According to the present disclosure, a technique is provided that can suppress the occurrence of defects in the molding of a casting mold for producing an iron-based casting without reducing productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of a casting mold forming method according to an embodiment of the present invention.

[0022] Figure 2 This is a graph showing the relationship between the amount of binder added and the flexural strength for each aggregate.

[0023] Figure 3 This is a graph showing the relationship between the amount of each binder added and the bending strength.

[0024] Figure 4 This is a graph showing the amount of residual sand on the casting surface after sand removal for each aggregate.

[0025] Figure 5 This is a graph showing the amount of residual sand on the casting skin after sand removal for each binder. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same or corresponding parts are denoted by the same reference numerals.

[0027] (Overview of the casting method)

[0028] A casting mold forming method according to one embodiment is a method of forming a casting mold. The casting mold is a main mold or a core for manufacturing an iron-based casting. The iron-based casting refers to a casting containing iron oxide (FeO) in the molten metal used in the manufacturing, such as cast iron.

[0029] Figure 1 FIG. 1 is a flow chart of a mold forming method according to an embodiment of the present invention. Figure 1 As shown, in the casting molding method, a kneading process (step S10) is first performed. In the kneading process (step S10), aggregate and a binder are mixed in a mixer.

[0030] Aggregate is artificial sand with an aluminum oxide (Al2O3) content of 60% or more and a silicon dioxide (SiO2) content of 40% or less. The % mark here indicates the average value of the components of a single grain of sand. As a more specific example, the aggregate is artificial sand with an aluminum oxide (Al2O3) content of 61% to 72% and a silicon dioxide (SiO2) content of 20% to 36%. Artificial sand is a particle, for example, a spherical particle. Artificial sand is manufactured, for example, by a sintering method or a melting method.

[0031] The sintering method is a method of granulating the particles in a spray dryer or a stirring mixer and then sintering the particles in a rotary kiln. The melting method is a method of granulating the particles and then melting them, or a method of melting the material in an electric arc furnace and then granulating them by atomization.

[0032] Artificial sand produced by the melting method tends to have a smaller specific surface area than artificial sand produced by the sintering method. Therefore, when using artificial sand produced by the melting method for molding, the amount of binder for solidifying the artificial sand can be reduced compared to the case of using artificial sand produced by the sintering method for molding. Thus, the casting molding method can reduce the manufacturing cost.

[0033] The binder is any one of sodium silicate and potassium silicate. The binder is 4 parts by weight or less relative to 100 parts by weight of the aggregate. That is, it means that the binder is 4 g or less relative to 100 g of the aggregate. For example, the binder is 1 to 4 parts by weight relative to 100 parts by weight of the aggregate. The molar ratio of the binder may also be 1.8 or more.

[0034] In the kneading process (step S10), the aggregate and the binder can be mixed and foamed. In this case, a surfactant can be added. The surfactant is, for example, an anionic surfactant. Thus, a whipped cream-like foamed kneaded sand can be obtained. Foamed kneaded sand refers to a mixture of solid particles and a foamed liquid. Foamed kneaded sand is a substance formed by a mixture of aggregate, a binder and a surfactant. Foamed kneaded sand contains not only aggregate, a binder and a surfactant, but also other materials. For example, the foamed kneaded sand may further contain at least one of inorganic compound particles and lithium salts that are poorly soluble in water. "Poorly soluble in water" means that when dissolved in 1L of water at 25°C, its solubility is less than 100 mg. The inorganic compound particles are, for example, carbonates or hydroxides, such as calcium carbonate, magnesium carbonate, magnesium hydroxide or aluminum hydroxide. As an example of a lithium salt, it is lithium silicate, lithium oxide, lithium hydroxide, lithium carbonate, lithium bromide, lithium chloride, lithium nitrate or lithium nitrite. By using foamed kneaded sand, the filling property of sand is improved.

[0035] After the preparation of the mixed sand is completed by the mixing process (step S10), a filling process (step S12) is performed. In the filling process (step S12), the mixed sand (an example of a mold material) is filled into the mold. The filling method is not particularly limited. The filling method can be changed according to the type of the curing method described later. The filling method includes, for example, air blowing filling using air flow filling, injection such as pressing, manual filling using manual operation, filling using vibration, or extrusion.

[0036] When the filling of the mixed sand is completed through the filling process (step S12), the solidification process (step S14) is performed. In the solidification process (step S14), the mixed sand filled in the mold is solidified. The solidification method is not particularly limited. The solidification method can be, for example, a method of utilizing a dehydration condensation reaction, a method of solidifying a binder with carbon dioxide (CO2) gas, a method of mixing about 2 to 4% of slag in the aggregate and using the slag as a solidifying agent, a method of adding an ester and an additive to the aggregate at the same time to mix and gelate, a method of solidifying the metal powder by reacting the metal powder with the alkali of the additive, etc. When the solidification process (step S14) is completed, Figure 1 The process shown is complete. After curing is complete, the master pattern or core is removed from the mold.

[0037] It should be noted that in the curing process (step S14), in the case of utilizing a dehydration condensation reaction, the foamed mixed sand is added to the heated metal mold in the filling process (step S12). In the curing process (step S14), in the case of curing the binder with carbon dioxide (CO2) gas, the mixed sand is filled into a wooden mold, a resin mold or a (heated) metal mold in the filling process (step S12). In the case of curing utilizing a dehydration condensation reaction and in the case of curing utilizing carbon dioxide (CO2) gas, a foundry with less odor and a good environment can be realized compared with other methods.

[0038] (Summary of Implementation Methods)

[0039] In the casting mold forming method involved in the embodiment, the silicon dioxide (SiO2) contained in the aggregate is less than 40%, and the content of silicon dioxide (SiO2) is greatly suppressed compared with natural silica sand containing more than 90% silicon dioxide (SiO2). Therefore, the casting mold formed by the casting mold forming method involved in the embodiment is less likely to produce iron olivine (2FeO·SiO2) than the casting mold formed by using natural silica sand as the aggregate. Therefore, the casting mold forming method involved in the embodiment can suppress the occurrence of casting sand sintering defects and poor filling on the surface of the casting compared with the case where natural silica sand is used as the aggregate. In addition, since iron olivine (2FeO·SiO2) is not easily produced, there is no need to apply a mold coating. Therefore, the casting mold forming method involved in the embodiment can suppress the occurrence of defects without reducing productivity.

[0040] In addition, in order to ensure the strength of the mold, it is necessary to add more binder. When natural silica sand is used as aggregate, more than 4 parts by weight of binder is usually added. However, when more binder is added, the disintegration of the mold becomes worse. In the mold making method involved in the embodiment, the aggregate is artificial sand, so that even if the amount of binder added is less than 4 parts by weight, the strength of the mold can be fully obtained. Therefore, the mold making method involved in the embodiment can ensure the strength of the mold and improve the disintegration of the mold.

[0041] Example

[0042] Hereinafter, examples and comparative examples implemented by the present inventors in order to confirm the effects of the present disclosure will be described.

[0043] [Test 1: Evaluation of mold strength]

[0044] Examples and comparative examples were prepared in which the type of aggregate and the amount of binder added were changed, and the mold strength was evaluated.

[0045] (Type of Aggregate)

[0046] As aggregates, two kinds of artificial sand and two kinds of natural silica sand were prepared.

[0047] [Table 1]

[0048]

[0049] (Binder, surfactant)

[0050] The binder was No. 1 water glass (manufactured by Fuji Chemical Co., Ltd.), and the surfactant was an anionic surfactant.

[0051] (Example 1)

[0052] Artificial sand 1 is used as aggregate. 100 parts by weight of artificial sand 1, 1 part by weight of a binder, and 0.25 parts by weight of a surfactant are mixed and foamed at about 200 rpm for about 5 minutes using a mixer (table mixer: manufactured by Aikosha Manufacturing Co., Ltd.) to prepare foamed kneaded sand. Next, the foamed kneaded sand is filled into a metal mold heated to 250°C using an injection filling device. The metal mold is a metal mold for making a bending strength test piece and has a capacity of about 80 cm 3 The cavity is filled with a gate speed of about 1 m / sec and a cylinder surface pressure of 0.4 MPa. The foamed kneaded sand filled in the heated metal mold is left for 2 minutes to solidify by the dehydration condensation reaction caused by the heat of the metal mold. After solidification, the core is removed from the metal mold.

[0053] [Examples 2 to 6]

[0054] In Example 2, the binder is set to 2 parts by weight. The rest is the same as in Example 1. In Example 3, the binder is set to 4 parts by weight. The rest is the same as in Example 1. In Example 4, artificial sand 2 is used as aggregate. The rest is the same as in Example 1. In Example 5, artificial sand 2 is used as aggregate. The rest is the same as in Example 2. In Example 6, artificial sand 2 is used as aggregate. The rest is the same as in Example 3.

[0055] [Comparative Examples 1 to 6]

[0056] In Comparative Example 1, natural silica sand 1 is used as aggregate. The rest is the same as in Example 1. In Comparative Example 2, natural silica sand 1 is used as aggregate. The rest is the same as in Example 2. In Comparative Example 3, natural silica sand 1 is used as aggregate. The rest is the same as in Example 3. In Comparative Example 4, natural silica sand 2 is used as aggregate. The rest is the same as in Example 1. In Comparative Example 5, natural silica sand 2 is used as aggregate. The rest is the same as in Example 2. In Comparative Example 6, natural silica sand 2 is used as aggregate. The rest is the same as in Example 3.

[0057] [Table 2]

[0058] Types of Aggregates Binder (parts by weight) Example 1 Artificial sand 1 1 Example 2 Artificial sand 1 2 Example 3 Artificial sand 1 4 Example 4 Artificial sand 2 1 Example 5 Artificial sand 2 2 Example 6 Artificial sand 2 4 Comparative Example 1 Natural silica sand1 1 Comparative Example 2 Natural silica sand1 2 Comparative Example 3 Natural silica sand1 4 Comparative Example 4 Natural silica sand 2 1 Comparative Example 5 Natural silica sand 2 2 Comparative Example 6 Natural silica sand 2 4

[0059] Sand test pieces of 10 mm × 10 mm × 140 mm were prepared from Examples 1 to 6 and Comparative Examples 1 to 6, and the bending strength was measured. The bending strength was measured according to JACT test method SM-1, bending strength test method. The results are shown in Figure 2 .

[0060] Figure 2 This is a graph showing the relationship between the amount of binder added and the flexural strength for each aggregate. Figure 2 In the figure, the horizontal axis is the amount of binder added (parts by weight) and the vertical axis is the bending strength (MPa). The core used in casting needs to have a strength that does not break during transportation or storage. Therefore, a bending strength of 3MPa or more is set as the necessary strength, and the measurement results are evaluated. The dotted line in the figure is a regression curve. Figure 2 As shown, in the case of the artificial sand 1 of Examples 1 to 3, it was confirmed that the bending strength of 3 MPa or more was achieved when the binder was 1 part by weight. In the case of the artificial sand 2 of Examples 4 to 6, it was confirmed that the bending strength of 3 MPa or more was achieved when the binder was 4 parts by weight (estimated to be about 2.5 parts by weight by the regression curve). In contrast, in the case of the natural silica sand 1 of Comparative Examples 1 to 3, although it was confirmed that the bending strength of 3 MPa or more was achieved when the binder was 4 parts by weight (estimated to be about 3.5 parts by weight by the regression curve), it was smaller than the bending strength of the artificial sand 2 of Examples 4 to 6. In the case of the natural silica sand 2 of Comparative Examples 4 to 6, the bending strength of 3 MPa or more was not achieved when the binder was 4 parts by weight. In the case of the natural silica sand 2 of Comparative Examples 4 to 6, it was estimated from the regression curve that 5.0 parts by weight of the binder was required to achieve a bending strength of 3 MPa or more. It was thus confirmed that by using artificial sand as aggregate, strength can be ensured with a small amount of binder compared to natural silica sand. The difference in the measurement results is believed to be due to the difference in shape and specific surface area between artificial sand and natural silica sand. It is believed that since the surface of artificial sand is smooth and the surface of natural silica sand is uneven, the specific surface area of ​​artificial sand is small, so even if the amount of binder used is small, the desired strength can be obtained.

[0061] [Test 2: Evaluation of mold strength]

[0062] Examples in which the type of binder and the amount of binder added were changed were produced, and the mold strength was evaluated.

[0063] (Type of adhesive)

[0064] As a binder, sodium silicate and potassium silicate were prepared in different molar ratios.

[0065] [Table 3]

[0066]

[0067] (Aggregate, surfactant)

[0068] The aggregate is artificial sand 1 in Table 1, and the surfactant is an anionic surfactant.

[0069] (Example 7)

[0070] Artificial sand 1 was used as aggregate. Artificial sand 1 was 100 parts by weight, binder 1 was 1 part by weight, and surfactant was 0.25 parts by weight. The production conditions were the same as those in Example 1.

[0071] [Examples 8 to 18]

[0072] In Examples 8 and 9, the amount of binder 1 is 2 parts by weight and 4 parts by weight. The rest is the same as in Example 7. In Examples 10 to 12, the amount of binder 2 is 1, 2, and 4 parts by weight. The rest is the same as in Example 7. In Examples 13 to 15, the amount of binder 3 is 1, 2, and 4 parts by weight. The rest is the same as in Example 7. In Examples 16 to 18, the amount of binder 4 is 1, 2, and 4 parts by weight. The rest is the same as in Example 7.

[0073] [Table 4]

[0074] aggregate Types of Binders Binder (parts by weight) Example 7 Artificial sand 1 Binder 1 1 Example 8 Artificial sand 1 Binder 1 2 Example 9 Artificial sand 1 Binder 1 4 Example 10 Artificial sand 1 Binder 2 1 Embodiment 11 Artificial sand 1 Binder 2 2 Example 12 Artificial sand 1 Binder 2 4 Embodiment 13 Artificial sand 1 Binder 3 1 Embodiment 14 Artificial sand 1 Binder 3 2 Embodiment 15 Artificial sand 1 Binder 3 4 Example 16 Artificial sand 1 Binder 4 1 Embodiment 17 Artificial sand 1 Binder 4 2 Embodiment 18 Artificial sand 1 Binder 4 4

[0075] Sand test pieces of 10 mm × 10 mm × 140 mm were prepared from Examples 7 to 18, and the flexural strength was measured. The flexural strength was measured according to JACT test method SM-1, flexural strength test method. The results are shown in Figure 3 .

[0076] Figure 3 This is a graph showing the relationship between the amount of each binder added and the bending strength. Figure 3 In the figure, the horizontal axis is the amount of binder added (parts by weight), and the vertical axis is the flexural strength (MPa). As in Test 1, the flexural strength of 3MPa or more was set as the required strength, and the measurement results were evaluated. The dotted line in the figure is a regression curve. Figure 3As shown, in the case of the adhesive 1 of Examples 7 to 9 (Examples 1 to 3), it was confirmed that a bending strength of 3 MPa or more was achieved when the adhesive was 1 part by weight. In the case of the adhesive 2 of Examples 10 to 12, it was confirmed that a bending strength of 3 MPa or more was achieved when the adhesive was 4 parts by weight (estimated to be about 2.5 parts by weight by the regression curve). In the case of the adhesive 3 of Examples 13 to 15, it was confirmed that a bending strength of 3 MPa or more was achieved when the adhesive was 2 parts by weight (estimated to be about 1.5 parts by weight by the regression curve). In the case of the adhesive 4 of Examples 16 to 18, it was confirmed that a bending strength of 3 MPa or more was achieved when the adhesive was 4 parts by weight. It was thus confirmed that a bending strength of 3 MPa or more was achieved when the adhesive was 1 to 4 parts by weight. In addition, it was confirmed that no matter what kind of adhesive, as long as it is at least 4 parts by weight, a bending strength of 3 MPa or more can be achieved.

[0077] [Test 3: Evaluation of disintegration]

[0078] The disintegrability of the molds (core, master mold) produced using each aggregate was evaluated.

[0079] Table 5 shows the parts by weight of the adhesive 1 required to achieve a bending strength of 3 MPa or more, estimated from the results of Test 1.

[0080] [Table 5]

[0081] Artificial sand 1 1.0 parts by weight Artificial sand 2 2.5 parts by weight Natural silica sand1 3.5 parts by weight Natural silica sand 2 5.0 parts by weight

[0082] <Core>

[0083] (Examples 19, 20, Comparative Examples 7, 8)

[0084] In Example 19, the core was prepared with 100 parts by weight of artificial sand 1, 1 part by weight of binder 1, and 0.25 parts by weight of anionic surfactant. In Example 20, the core was prepared with 100 parts by weight of artificial sand 2, 2.5 parts by weight of binder 1, and 0.25 parts by weight of anionic surfactant. In Comparative Example 7, the core was prepared with 100 parts by weight of natural silica sand 1, 3.5 parts by weight of binder 1, and 0.25 parts by weight of anionic surfactant. In Comparative Example 8, the core was prepared with 100 parts by weight of natural silica sand 2, 5.0 parts by weight of binder 1, and 0.25 parts by weight of anionic surfactant. The manufacturing conditions of Examples 19, 20, and Comparative Examples 7 and 8 were the same as those of Example 1, and a core of 10 mm×10 mm×140 mm was obtained.

[0085] <Main Model>

[0086] (Example 21)

[0087] Use a mixer (table mixer: Aikosha Manufacturing Co., Ltd.) to mix 100 parts by weight of artificial sand 1 and 1 part by weight of binder 1 at about 200 rpm for about 5 minutes to prepare wet mixed sand. Next, fill the mixed sand into a wooden mold manually. Use a wooden mold that can cast 30mm×30mm×100mm castings and can shape a main mold with a recovered 10mm×10mm×140mm core. Blow carbon dioxide (CO2) into the mixed sand filled in the wooden mold for 30 seconds to solidify it. After solidification is completed, remove the main mold from the wooden mold.

[0088] (Example 22, Comparative Examples 9 and 10)

[0089] In Example 22, the master mold was prepared with 100 parts by weight of artificial sand 2 and 2.5 parts by weight of binder 1. In Comparative Example 9, the master mold was prepared with 100 parts by weight of natural silica sand 1 and 3.5 parts by weight of binder 1. In Comparative Example 10, the master mold was prepared with 100 parts by weight of natural silica sand 2 and 5.0 parts by weight of binder 1. The manufacturing conditions of Example 22 and Comparative Examples 9 and 10 were the same as those of Example 21.

[0090] [Table 6]

[0091]

[0092] Cast iron FC200 was cast using the core and master mold of casting number 1. Casting was performed without applying mold coating to the core and master mold. After casting, in order to remove sand from the casting, the gate was hit 10 times with a hammer, and the core was visually confirmed to be collapsed, and the weight of sand attached to the casting was measured. For casting numbers 2 to 4, the core was visually confirmed to be collapsed under the same conditions, and the weight of sand attached to the casting was measured.

[0093] <Visual inspection results of core disintegration>

[0094] For the artificial sand of casting numbers 1 and 2, the core collapsed and part of the core became a through hole. In contrast, for the natural silica sand of casting numbers 3 and 4, the core did not collapse and remained in the casting. It was confirmed that it is difficult to achieve both the strength and disintegration of the core when natural silica sand is used as aggregate. It was also confirmed that by using artificial sand as aggregate, it is possible to achieve both the strength and disintegration of the core.

[0095] <Sand attached to casting>

[0096] Figure 4 This graph shows the amount of residual sand on the casting surface after sand removal for each aggregate. The horizontal axis is the casting number and the vertical axis is the amount of residual sand. Figure 4As shown, in casting No. 1 where the aggregate is artificial sand, the amount of residual sand is about 2g, and in casting No. 2 where the aggregate is artificial sand, the amount of residual sand is about 6g. Thus, in the case where the aggregate is artificial sand, the sand is slightly attached to the casting. In contrast, in casting No. 3 where the aggregate is natural silica sand, the amount of residual sand is about 36g, and in casting No. 4 where the aggregate is natural silica sand, the amount of residual sand is about 32g. Moreover, the natural silica sand solidifies and surrounds the casting. It should be noted that since natural silica sand produces casting sand sintering defects, the weight of the natural silica sand that can be removed from the casting with a metal file is measured. Thus, it is confirmed that, in the case of natural silica sand as aggregate, it is difficult to take into account the strength and disintegration of the main mold. It is also confirmed that by using artificial sand as aggregate, the strength and disintegration of the main mold can be taken into account.

[0097] [Test 4: Evaluation of disintegration]

[0098] The disintegrability of the core and the master mold produced using each binder was evaluated.

[0099] Table 7 shows the weight parts of each binder required to achieve a bending strength of 3 MPa or more for the artificial sand 1, which was estimated from the results of Test 2.

[0100] [Table 7]

[0101] Binder 1 1.0 parts by weight Binder 2 2.5 parts by weight Binder 3 1.5 parts by weight Binder 4 4.0 parts by weight

[0102] <Core>

[0103] [Examples 23 to 26]

[0104] In Example 23, the core was prepared with 100 parts by weight of artificial sand 1, 1 part by weight of binder 1, and 0.25 parts by weight of anionic surfactant. In Example 24, the core was prepared with 100 parts by weight of artificial sand 1, 2.5 parts by weight of binder 2, and 0.25 parts by weight of anionic surfactant. In Example 25, the core was prepared with 100 parts by weight of artificial sand 1, 1.5 parts by weight of binder 3, and 0.25 parts by weight of anionic surfactant. In Example 26, the core was prepared with 100 parts by weight of artificial sand 1, 4.0 parts by weight of binder 4, and 0.25 parts by weight of anionic surfactant. The preparation conditions of Examples 23 to 26 are the same as those of Example 1.

[0105] <Main Model>

[0106] [Examples 27 to 30]

[0107] In Example 27, the master mold was prepared with 100 parts by weight of artificial sand 1 and 1 part by weight of binder 1. In Example 28, the master mold was prepared with 100 parts by weight of artificial sand 1 and 2.5 parts by weight of binder 2. In Example 29, the master mold was prepared with 100 parts by weight of artificial sand 1 and 1.5 parts by weight of binder 3. In Example 30, the master mold was prepared with 100 parts by weight of artificial sand 1 and 4.0 parts by weight of binder 4. The manufacturing conditions of Examples 27 to 30 are the same as those of Example 21.

[0108] [Table 8]

[0109]

[0110] Cast iron FC200 was cast using the core and master mold of casting number 5. Casting was performed without applying mold coating to the core and master mold. After casting, in order to remove sand from the casting, the gate was hit 10 times with a hammer, and the core was visually confirmed to be broken, and the weight of sand attached to the casting was measured. For casting numbers 6 to 8, the core was visually confirmed to be broken under the same conditions, and the weight of sand attached to the casting was measured.

[0111] <Visual inspection results of core disintegration>

[0112] The cores collapsed and parts of the cores became through holes in the artificial sands of casting numbers 5 to 8. This confirmed that, regardless of the type of binder, by using artificial sand as an aggregate, both the strength and the disintegration of the cores can be achieved.

[0113] <Sand attached to casting>

[0114] Figure 5 This is a graph showing the amount of residual sand on the casting surface after sand removal for each binder. The horizontal axis is the casting number and the vertical axis is the amount of residual sand. Figure 5 As shown, it was confirmed that in casting numbers 5 to 8 where the aggregate was artificial sand, the amount of residual sand was less than 4 g, and regardless of the type of binder, when the aggregate was artificial sand, the sand was slightly attached to the casting. In addition, it was confirmed that regardless of the type of binder, by using artificial sand as aggregate, the strength and disintegration of the main mold can be achieved.

[0115] As mentioned above, although the embodiment shown by way of example has been described, the present invention is not limited to the embodiment shown by way of example, and various omissions, substitutions, and changes can be made.

[0116] Various exemplary embodiments included in the present disclosure include the following.

[0117] [Item 1]

[0118] A casting mold molding method is a casting mold molding method for molding a casting mold for manufacturing iron castings, comprising:

[0119] Steps for making mixed sand using artificial sand as aggregate and binder,

[0120] The step of filling the above mixed sand into a mold,

[0121] The step of solidifying the kneaded sand filled in the mold.

[0122] [Item 2]

[0123] The casting mold forming method according to item 1, wherein:

[0124] In the artificial sand, the content of aluminum oxide (Al2O3) is 60% or more, and the content of silicon dioxide (SiO2) is 40% or less.

[0125] The binder is any one of sodium silicate and potassium silicate.

[0126] [Item 3]

[0127] The casting mold forming method according to item 1 or 2, wherein the molar ratio of the binder is 1.8 or more.

[0128] [Item 4]

[0129] The casting mold making method according to any one of Items 1 to 3, wherein the binder is 4 parts by weight or less based on 100 parts by weight of the aggregate.

[0130] [Item 5]

[0131] The casting mold making method according to any one of Items 1 to 4, wherein the artificial sand is produced by a melting method or a sintering method.

[0132] [Item 6]

[0133] The casting mold making method according to any one of Items 1 to 5, wherein in the solidification step, the kneaded sand is solidified by a dehydration condensation reaction.

[0134] [Item 7]

[0135] The casting mold making method according to any one of items 1 to 6, wherein in the solidification step, the kneaded sand is solidified using carbon dioxide (CO 2 ) gas.

[0136] [Item 8]

[0137] The casting mold making method according to any one of Items 1 to 7, wherein the kneaded sand is foamed kneaded sand containing a surfactant.

[0138] [Item 9]

[0139] A casting mold material is a casting mold material for manufacturing iron-based castings, which contains artificial sand with an alumina (Al2O3) content of more than 60% and a silicon dioxide (SiO2) content of less than 40% as aggregate, and contains either sodium silicate or potassium silicate as a binder.

Claims

1. A casting mold molding method is a casting mold molding method for molding a casting mold for manufacturing iron castings, comprising: The process of preparing mixed sand using artificial sand as aggregate and a binder, The step of filling the mixed sand into a mold, The step of solidifying the kneaded sand filled in the mold.

2. The casting mold forming method according to claim 1, wherein: In the artificial sand, aluminum oxide Al2O3 accounts for more than 60%, and silicon dioxide SiO2 accounts for less than 40%. The binder is any one of sodium silicate and potassium silicate.

3. The casting mold forming method according to claim 1 or 2, wherein: The molar ratio of the binder is greater than 1.

8.

4. The casting mold forming method according to claim 1 or 2, wherein: The binder is contained in an amount of 4 parts by weight or less based on 100 parts by weight of the aggregate.

5. The casting mold forming method according to claim 1 or 2, wherein: The artificial sand is produced by a melting method or a sintering method.

6. The casting mold forming method according to claim 1 or 2, wherein: In the solidification step, the kneaded sand is solidified by a dehydration condensation reaction.

7. The casting mold forming method according to claim 1 or 2, wherein: In the solidification step, the kneaded sand is solidified using carbon dioxide (CO 2 ) gas.

8. The casting mold forming method according to claim 1 or 2, wherein: The kneaded sand is foamed kneaded sand containing at least a surfactant.

9. A casting mold material, which is a casting mold material for manufacturing a casting mold for an iron-based casting, wherein: The invention discloses an artificial sand containing 60% or more of aluminum oxide Al2O3 and 40% or less of silicon dioxide SiO2 as aggregate, and contains either sodium silicate or potassium silicate as a binder.

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