CASTING FORMING PROCESS AND CASTING MATERIAL

Abstract

A mold forming method of forming a mold for producing iron castings includes preparing a mixed sand using casting sand as a solid and a binder, filling a mold with the mixed sand, and solidifying the mixed sand filled in the mold.

Description

Technical area

[0001] The present disclosure relates to a mold forming method and a molding material. Technical background

[0002] Patent Document 1 discloses a mold. The mold is manufactured by bonding molded quartz sand using a binder. The main component of the quartz sand is silicon dioxide (SiO2). Literature listPatent document

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-527915 Description of the inventionTechnical task

[0004] When the mold described in Patent Document 1 is used to manufacture iron castings, metal oxides (e.g., FeO) in the molten metal may react with silicon dioxide (SiO2) contained in the quartz sand, which is the solid material of the mold, to form fayalite (2FeO·SiO2). Fayalite (2FeO·SiO2) may cause burn-on defects on the surface of the casting or lead to penetration. To reduce defects, it is conceivable to apply a coating to the mold. However, this increases the manufacturing process steps and reduces productivity. This disclosure provides a method for suppressing defects in the mold formation of molds for manufacturing iron castings without reducing productivity. Solution to the problem

[0005] A mold forming method according to one aspect of the present invention is a method of forming a mold for producing iron castings. The method includes the following steps: (1) producing a mixed sand using casting sand as a solid and a binder; (2) filling a mold with the mixed sand; (3) solidification of the mixed sand filled into the mold.

[0006] In this mold forming method, since casting sand is used as the solid, the silicon dioxide (SiO2) content is significantly reduced compared to natural quartz sand, which contains more than 90% silicon dioxide (SiO2). Therefore, the mold produced by this mold forming method is less likely to produce fayalite (2FeO·SiO2) than one produced using natural quartz sand as the solid. Thus, this mold forming method can reduce the occurrence of overfiring defects and penetration on the surface of the casting compared to a case where natural quartz sand is used as the solid. Furthermore, since fayalite (2FeO·SiO2) is less likely to be produced, there is no need to apply a coating to the mold. Therefore, this mold forming method can reduce the occurrence of defects without reducing productivity.

[0007] In one embodiment, the casting sand could contain 60% or more alumina (Al2O3) and 40% or less silicon dioxide (SiO2) and the binder could be either sodium silicate or potassium silicate.

[0008] In one embodiment, the binder could have a molar ratio of 1.8 or more. In this case, the mold forming process can improve the collapse properties of the mold while maintaining the strength of the mold.

[0009] In one embodiment, the binder may be 4 parts by weight or less per 100 parts by weight of the solid. To ensure the strength of the mold, it is necessary to add a larger amount of binder. When natural quartz sand is used as the solid, the binder is generally added in an amount greater than 4 parts by weight. However, the collapsibility of the mold deteriorates when a larger amount of binder is added. In this mold forming method, by using casting sand as the solid, sufficient mold strength can be obtained even if the amount of binder added is 4 parts by weight or less. Therefore, this mold forming method can improve the collapsibility of the mold while maintaining the mold strength.

[0010] In one embodiment, the casting sand could be produced by a melting process or a sintering process. Casting sand produced by the melting process or the sintering process can reduce the amount of binder compared to casting sand produced by other processes, thereby reducing manufacturing costs.

[0011] In one embodiment, in the solidification step, the mixed sand could be solidified through a dehydration-condensation reaction. When solidification through a dehydration-condensation reaction is used, the mixed sand can be blown into a heated mold in a moist state, or a foamed mixed sand can be injected. This mold-forming method can realize a casting facility with less odor and better environmental performance. On the other hand, when solidification is performed using an ester, an odor associated with organic substances is generated, and when solidification is performed by reacting metal powder with water glass, hydrogen is generated.

[0012] In one embodiment, the mixed sand could be solidified in the solidification step using carbon dioxide (CO2) gas. When solidification using carbon dioxide (CO2) gas is used, the mixed sand can be filled in a wet state by hand in the filling step, or by vibration filling, pressing, or injection filling. This mold forming method can realize a casting facility with less odor and better environmental performance. On the other hand, when solidification is performed using an ester, an odor associated with organic substances is generated, and when solidification is performed by reacting metal powder with water glass, hydrogen is generated.

[0013] In one embodiment, the mixed sand could be foamed mixed sand containing a surfactant. This mold formation method can improve the fillability of the sand and reduce the occurrence of defects without reducing productivity by using foamed mixed sand with casting sand as the solid.

[0014] A mold material according to another aspect of the present disclosure is a material for a mold for producing iron castings. The mold material includes casting sand containing 60% or more alumina (Al2O3) and 40% or less silicon dioxide (SiO2) as the solid, and either sodium silicate or potassium silicate as the binder. This casting material has a silicon dioxide (SiO2) content of 40% or less in the solid, and compared to natural quartz sand containing more than 90% silicon dioxide (SiO2), the silicon dioxide (SiO2) content is significantly reduced. Therefore, the mold produced using this mold material is less likely to produce fayalite (2FeO·SiO2) compared to a mold produced using natural quartz glass as the solid.Therefore, this mold material can reduce the occurrence of firing defects and penetration of the casting surface compared to a case where natural quartz sand is used as the solid. Furthermore, since fayalite (2FeO SiO2) is less likely to be generated, it is not necessary to apply a coating to the mold. Therefore, this mold material can reduce the occurrence of defects without reducing productivity. Advantageous effects of the invention

[0015] According to this disclosure, a method is provided that reduces the occurrence of defects in the mold forming of molds for producing iron castings without reducing productivity. Short character description Fig. 1 is a flowchart of a mold forming method according to an embodiment. Fig.Figure 2 is a graph showing the relationship between the amount of binder added and the flexural strength for each solid. Fig. Figure 3 is a graph showing the relationship between the amount of binder added and the flexural strength for each binder. Fig. Figure 4 is a graph showing the amount of sand adhering to the casting surface after sand removal for each solid. Fig. Figure 5 is a graph showing the amount of sand adhering to the casting surface after sand removal for each binder. Description of embodiments

[0016] Embodiments of the present invention are described below with reference to the drawings. In the drawings, like or equivalent parts are designated by like reference numerals.

[0017] (Overview of the Mold Forming Method) A mold forming method according to one embodiment forms a mold. The mold is a master mold or core for producing iron castings. Iron castings are castings produced using molten metal containing iron oxide (FeO). Iron castings include, for example, cast iron.

[0018] Figure 1 is a flowchart of a mold forming method according to one embodiment. As shown in Fig. As shown in Figure 1, a mixing process (step S10) is first performed in the mold formation process. In the mixing process (step S10), the solid and the binder are mixed in a mixing machine.

[0019] The solid is foundry sand containing 60% or more of alumina (Al2O3) and 40% or less of silicon dioxide (SiO2). Here, the percentage notation (%) represents the average value of the components of a single grain of sand. A more concrete example is foundry sand containing 61% or more of alumina (Al2O3) and 72% or less of silicon dioxide (SiO2), and 20% or more of silicon dioxide (SiO2) and 36% or less of silicon dioxide. The foundry sand is in the form of particles, for example, spherical particles. The foundry sand is produced, for example, by a sintering process or a melting process.

[0020] The sintering process is a process in which fine particles are granulated using a spray dryer or an agitator-mixer and then sintered in a rotary kiln. The melting process is a process in which fine particles are granulated and then melted, or a process in which materials are melted in an arc furnace and then atomized to form particles.

[0021] Casting sand produced by the melting process tends to have a smaller specific surface area than that produced by the sintering process. Therefore, when mold forming is performed using casting sand produced by the melting process, the amount of binder required to solidify the casting sand can be reduced compared to when mold forming is performed using casting sand produced by the sintering process. This mold forming method can reduce manufacturing costs.

[0022] The binder is either sodium silicate or potassium silicate. The binder is composed of 4 parts by weight or less per 100 parts by weight of the solid. This means that the binder makes up 4 grams or less per 100 grams of the solid. As an example, the binder makes up 1 part by weight or more and 4 parts by weight or less per 100 parts by weight of the solid. The binder can have a molar ratio of 1.8 or more.

[0023] During the mixing process (step S10), the solid and the binder could be mixed during foaming. In this case, a surfactant could be added. The surfactant is, for example, an anionic surfactant. This creates a foamed mixed sand with a whipped cream-like consistency. Foamed mixed sand is a mixed sand made up of solid particles and a foamed liquid. Foamed mixed sand is a mixture of the solid, the binder, and the surfactant. Foamed mixed sand can contain not only the solid, the binder, and the surfactant, but also other materials. For example, the foamed mixed sand could further contain simply water-soluble inorganic compound particles and / or lithium salts."Poorly water-soluble" means that the solubility is 100 milligrams or less when dissolved in one liter of water at 25°C. The inorganic compound particles include carbonates or hydroxides, such as calcium carbonate, magnesium carbonate, magnesium hydroxide, or aluminum hydroxide. Examples of lithium salts include lithium silicate, lithium oxide, lithium hydroxide, lithium carbonate, lithium bromide, lithium chloride, lithium nitrate, or lithium nitride. Using foamed mixed sand increases the fillability of the sand.

[0024] When the preparation of the mixed sand in the mixing process (step S10) is completed, a filling process (step S12) is performed. In the filling process (step S12), the mixed sand (an example of the molding material) is filled into the mold. The filling method is not particularly limited. The filling method may be changed according to the type of solidification process to be described later. Examples of the filling method include air blowing, injection such as pressure feeding, hand filling, vibration filling, or pressing.

[0025] When the filling of the mixed sand in the filling process (step S12) is completed, a solidification step (step S14) is carried out. In the solidification step (step S14), the mixed sand introduced into the mold is solidified. The solidification method is not particularly limited. Examples of the solidification method include a method using a dehydration condensation reaction, a method of hardening the binder with a carbon dioxide (CO2) gas, a method of mixing 2 to 4% slag to the solid and using the slag as the hardening agent, a method of gelation by mixing an ester and an auxiliary agent with the solid, and a method of hardening by reacting a metal powder with an alkali of the auxiliary agent. When the solidification process (step S14) is completed, the Fig.1. After solidification is complete, the master mold or core is removed from the mold.

[0026] When the dehydration-condensation reaction is used in the solidification process (step S14), the foamed mixed sand is poured into the heated mold in the filling process (step S12). When the binder is hardened with carbon dioxide (CO2) gas in the solidification process (step S14), the mixed sand is poured into a wooden mold, a plastic mold, or a (heated) permanent mold in the filling process (step S12). When solidification through a dehydration-condensation reaction is used and when solidification using carbon dioxide (CO2) gas is used, a foundry with less odor and a better environment can be realized compared to other methods. (Summary of embodiments)

[0027] In the mold forming method according to the embodiment, the silicon dioxide (SiO2) content in the solid is 40% or less, and compared with natural quartz sand, which contains more than 90% silicon dioxide (SiO2), the silicon dioxide (SiO2) content is significantly reduced. Therefore, compared with a mold formed using natural quartz sand as the solid, fayalite (2FeO·SiO2) is less likely to be generated in the mold formed by the mold forming method according to the embodiment. Thus, the mold forming method according to the embodiment can reduce the occurrence of firing defects and penetration on the surface of the casting compared with the case where natural quartz sand is used as the solid. Furthermore, since fayalite (2FeO·SiO2) is less likely to be generated, there is no need to apply a coating to the mold.Therefore, the mold forming method according to the embodiments can reduce the occurrence of defects without reducing productivity.

[0028] Furthermore, to increase the strength of the mold, it is necessary to add a larger amount of binder. When natural quartz sand is used as the solid, the binder is generally added in an amount greater than 4 parts by weight. However, if a larger amount of binder is added, the collapsibility of the mold deteriorates. In the mold forming method according to the embodiments, sufficient mold strength can be achieved by using cast sand as the solid even if the amount of binder added is 4 parts by weight or less. Therefore, the mold forming method according to the embodiments can improve the collapsibility of the mold while maintaining the mold strength. Examples

[0029] Examples and comparative examples conducted by the inventors to confirm the effects of this disclosure are described below. [Test 1: Assessment of dimensional stability]

[0030] Examples and comparative examples were produced by varying the types of solids and the amounts of binder added, and the mold strength was evaluated. (Types of solids)

[0031] Two types of casting sand and two types of natural quartz sand were prepared as solids. Table 1 Type of solid Manufacturing process Product name Al2O3 component SiO2 component Casting sand 1 Melting process ESPEARL#60 (manufactured by YAMAKAWA SANGYO CO., LTD.) 72% 20% Casting sand 2 Sintering process CERABEADS#650 (manufactured by ITOCHU CERATECH CORPORATION) 61% 36% Natural quartz sand 1 - FLATTERY (manufactured by MITSUBISHI SHOJI CONSTRUCTION MATERIALS CORPORATION) 0,05% 99,85% Natural quartz sand 2 - MIKAWA SILICA SAND NO. 6 (manufactured by MIKAWA KEISEKI CO., LTD.) 0,66% 98,09% (binder, surfactant)

[0032] The binder was No. 1 Water Glass (manufactured by FUJI CHEMICAL CO. LTD.) and the surfactant was an anionic surfactant. (Example 1)

[0033] Casting sand 1 was used as the solid. Casting sand 1 was 100 parts by weight, the binder was 1 part by weight, and the surfactant was 0.25 parts by weight. These materials were mixed and foamed at approximately 200 rpm for approximately 5 minutes using a mixer (tabletop mixer: manufactured by AICOHSHA MFG. CO., LTD.) to produce foamed mixed sand. Next, this foamed mixed sand was injected into a mold heated to 250°C using an injection filling device. The mold was a mold for producing flexural strength test pieces and had a cavity with a volume of approximately 80 cm³. 3The foamed mixed sand was poured into the mold at an outlet velocity of approximately 1 m / s and a cylinder surface pressure of 0.4 MPa. The foamed mixed sand was poured into the heated mold and left for 2 minutes to solidify through a dehydration-condensation reaction due to the heat of the mold. After solidification was complete, the core was removed from the mold. (Examples 2 to 6)

[0034] In Example 2, the binder was 2 parts by weight. Other conditions were the same as in Example 1. In Example 3, the binder was 4 parts by weight. Other conditions were the same as in Example 1. In Example 4, casting sand 2 was used as the solid. Other conditions were the same as in Example 1. In Example 5, casting sand 2 was used as the solid. Other conditions were the same as in Example 2. In Example 6, casting sand was used as the solid. Other conditions were the same as in Example 3. (Comparison examples 1 to 6)

[0035] In Comparative Example 1, natural quartz sand 1 was used as the solid. Other conditions were the same as in Example 1. In Comparative Example 2, natural quartz sand 1 was used as the solid. Other conditions were the same as in Example 2. In Comparative Example 3, natural quartz sand 1 was used as the solid. Other conditions were the same as in Example 3. In Comparative Example 4, natural quartz sand 2 was used as the solid. Other conditions were the same as in Example 1. In Comparative Example 5, natural quartz sand 2 was used as the solid. Other conditions were the same as in Example 2. In Comparative Example 6, natural quartz sand 2 was used as the solid. Other conditions were the same as in Example 3. Table 2 Type of solid Binder (parts by weight) Example 1 Casting sand 1 1 Example 2 Casting sand 1 2 Example 3 Casting sand 1 4 Example 4 Casting sand 2 1 Example 5 Casting sand 2 2 Example 6 Casting sand 2 4 Comparison example 1 Natural quartz sand 1 1 Comparison example 2 Natural quartz sand 1 2 Comparison example 3 Natural quartz sand 1 4 Comparison example 4 Natural quartz sand 2 1 Comparison example 5 Natural quartz sand 2 2 Comparison example 6 Natural quartz sand 2 4

[0036] 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 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 Fig. 2 shown.

[0037] Fig. Figure 2 is a graph showing the relationship between the amount of binder added and the flexural strength for each solid. Fig.2, the horizontal axis represents the amount of binder added (parts by weight), and the vertical axis represents the flexural strength (MPa). Cores used in a casting require strength that prevents them from breaking during transportation or when placed in the mold. Therefore, the required strength was set to a flexural strength of 3 MPa or more, and the measurement results were evaluated. The dashed line in the figure is the regression curve. As shown in Fig.As shown in Figure 2, in the case of Casting Sand 1 in Examples 1 to 3, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 1 part by weight. In the case of Casting Sand 2 in Examples 4 to 6, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 4 parts by weight (estimated from the regression curve as approximately 2.5 parts by weight). In comparison, in the case of natural quartz sand 1 in Comparative Examples 1 to 3, although a flexural strength of 3 MPa or more was achieved when the binder was 4 parts by weight (estimated as about 3.5 parts by weight from the regression curve), the flexural strength was found to be lower than that of the casting sand 2 in Examples 4 to 6. In the case of natural quartz sand 2 in Comparative Examples 4 to 6, a flexural strength of 3 MPa or more was not achieved even when the binder was 4 parts by weight.In Comparative Examples 4 to 6 using natural quartz sand 2, it is estimated from the regression curve that 5 parts by weight of binder are required to achieve a flexural strength of 3 MPa or more. Thus, it was confirmed that using cast sand as the solid, the required strength can be ensured with a smaller amount of binder compared to natural quartz sand. It is believed that this difference in the measurement results is influenced by the differences in shape and specific surface area between cast sand and natural quartz sand. Cast sand has a flat surface, while natural quartz sand has many surface irregularities, so cast sand has a lower specific surface area and can achieve the desired strength with a smaller amount of binder. [Test 2: Assessment of form stability]

[0038] Examples were prepared by varying the types of binders and the amounts of binder added, and the mold strength was evaluated. (Types of binders)

[0039] Sodium silicate and potassium silicate with different molar ratios were prepared as binders. Table 3 Type of binder Molar ratio Product name Concentration of aqueous solution Binder 1 Sodium silicate 2,0 No. 1 Water Glass (manufactured by FUJI CHEMICAL CO., LTD.) 45% Binder 2 Sodium silicate 3,1 No. 3 Water Glass (manufactured by FUJI CHEMICAL CO., LTD.) 38% Binder 3 potassium silicate 1,8 1K Potassium Silicate (manufactured by NIPPON CHEMICAL INDUSTRIAL CO., LTD.) 50% Binder 4 potassium silicate 3,4 2K potassium silicate (manufactured by NIPPON CHEMICAL INDUSTRIAL CO., LTD.) 29% (solid, surface-active substance)

[0040] The solid was casting sand 1 from Table 1 and the surfactant was an anionic surfactant. (Example 7)

[0041] Casting sand 1 was used as the solid. Casting sand 1 was 100 parts by weight, binder 1 was 1 part by weight, and the surfactant was 0.25 parts by weight. The preparation conditions were the same as in Example 1. (Examples 8 to 18)

[0042] In Examples 8 and 9, Binder 1 was 2 parts by weight and 4 parts by weight, respectively. Other conditions were the same as in Example 7. In Examples 10 to 12, Binder 2 was 1.2 parts by weight and 4 parts by weight, respectively. Other conditions were the same as in Example 7. In Examples 13 to 15, Binder 3 was 1.2 parts by weight and 4 parts by weight, respectively. Other conditions were the same as in Example 7. In Examples 16 to 18, Binder 4 was 1.2 parts by weight and 4 parts by weight, respectively. Other conditions were the same as in Example 7. Table 4 solid Type of binder Binder (parts by weight) Example 7 Casting sand 1 Binder 1 1 Example 8 Casting sand 1 Binder 1 2 Example 9 Casting sand 1 Binder 1 4 Example 10 Casting sand 1 Binder 2 1 Example 11 Casting sand 1 Binder 2 2 Example 12 Casting sand 1 Binder 2 4 Example 13 Casting sand 1 Binder 3 1 Example 14 Casting sand 1 Binder 3 2 Example 15 Casting sand 1 Binder 3 4 Example 16 Casting sand 1 Binder 4 1 Example 17 Casting sand 1 Binder 4 2 Example 18 Casting sand 1 Binder 4 4

[0043] Sand test pieces measuring 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 Fig. 3 shown.

[0044] Fig.Figure 3 is a graph showing the relationship between the amount of binder added and the flexural strength for each binder. Fig. 3, the horizontal axis represents the added amount of binder (part by weight) and the vertical axis represents the flexural strength (MPa). As in Test 1, the required strength was set to a flexural strength of 3 MPa or more, and the measurement results were evaluated. The dashed line in the figure is a regression curve. As in Fig.As shown in Figure 3, in the case of Binder 1 of Examples 7 to 9 (Examples 1 to 3), it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 1 part by weight. In the case of Binder 2 of Examples 10 to 12, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 4 parts by weight (determined from the regression curve as approximately 2.5 parts by weight). In the case of Binder 3 of Examples 13 to 15, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 2 parts by weight (determined from the regression curve as approximately 1.5 parts by weight). In the case of Binder 4 of Examples 16 to 18, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 4 parts by weight.Thus, it was confirmed that a flexural strength of 3 MPa or more was achieved when the binder was 1 to 4 parts by weight. Furthermore, it was confirmed that a flexural strength of 3 MPa or more was achieved with at least 4 parts by weight of any binder. [Test 3: Assessment of collapsible properties]

[0045] The collapse properties of molds (cores, master molds) prepared using each solid were evaluated.

[0046] The parts by weight of Binder 1 required to achieve a flexural strength of 3 MPa or more, estimated from the results of Test 1, are shown in Table 5. Table 5 Casting sand 1 1.0 part by weight Casting sand 2 2.5 parts by weight Natural quartz sand 1 3.5 parts by weight Natural quartz sand 2 5.0 parts by weight

[0047] <kern>(Examples 19, 20, Comparative Examples 7, 8) In Example 19, a core was prepared using 100 parts by weight of casting sand 1, 1 part by weight of binder 1, and 0.25 part by weight of anionic surfactant. In Example 20, a core was prepared using 100 parts by weight of casting sand 2, 2.5 parts by weight of binder 1, and 0.25 part by weight of an anionic surfactant. In Comparative Example 7, a core was prepared using 100 parts by weight of natural quartz sand 1, 3.5 parts by weight of binder 1, and 0.25 part by weight of an anionic surfactant. In Comparative Example 8, a core was prepared using 100 parts by weight of natural quartz sand 2, 5.0 parts by weight of Binder 1 and 0.25 parts by weight of an anionic surfactant.The manufacturing conditions for Examples 19, 20 and Comparative Examples 7, 8 were the same as in Example 1 and cores of 10 mm × 10 mm × 140 mm were obtained. <masterform>(Example 21)

[0048] A material consisting of 100 parts by weight of casting sand 1 and 1 part by weight of binder 1 was mixed at approximately 200 rpm for approximately 5 minutes using a mixer (stand mixer: manufactured by AICOHSHA MFG. CO., LTD.) to produce wet mixed sand. Next, this mixed sand was manually poured into a wooden mold. A wooden mold capable of casting a 30 mm × 30 mm × 100 mm casting and accommodating a 10 mm × 10 mm × 140 mm core was used. Carbon dioxide (CO2) was injected into the mixed sand poured into the wooden mold for 30 seconds to solidify the mixed sand. After solidification was complete, the master mold was removed from the wooden mold. (Example 22, Comparative Examples 9, 10)

[0049] In Example 22, a master mold was prepared using 100 parts by weight of casting sand 2 and 2.5 parts by weight of binder 1. In Comparative Example 9, a master mold was prepared using 100 parts by weight of natural quartz sand 1 and 3.5 parts by weight of binder 1. In Comparative Example 10, a master mold was prepared using 100 parts by weight of natural quartz sand 2 and 5.0 parts by weight of binder 1. The production conditions for Example 22 and Comparative Examples 9 and 10 were the same as those in Example 21. Table 6 Casting number r core Masterform solid Type of binder Binder (parts by weight) 1 Example 19 Example 21 Casting sand 1 Binder 1 1,0 2 Example 20 Example 22 Casting sand 1 Binder 1 2,5 3 Comparison example 7 Comparison example 9 Natural quartz sand 1 Binder 1 3,5 4 Comparison example 8 Comparison example 10 Natural quartz sand 1 Binder 1 5,0

[0050] Using the core and master mold from casting number 1, FC200 cast iron was cast. The casting was performed without applying any coating to the core and master mold. After casting, the sprue was hammered 10 times to remove the sand from the casting. The collapse properties of the core were visually inspected and the weight of the sand adhering to the casting was measured. The same conditions were used to visually inspect the collapse properties of the cores and measure the weight of the sand adhering to the casting for casting numbers 2 to 4. <Visuelle Ergebnisse der Kollabiereigenschaften von Kernen>

[0051] In the casting sand of casting numbers 1 and 2, the cores collapsed, and the core parts became through holes. In comparison, in the natural quartz sand of casting numbers 3 and 4, the cores did not collapse and remained in the casting. This confirmed that it is difficult to achieve both the strength and the collapsibility of the cores when using natural quartz sand as the solid. Furthermore, it was confirmed that both the strength and the collapsibility of the cores can be achieved using casting sand as the solid. <Am Gussteil anhaftender Sand>

[0052] Fig. Figure 4 is a graph showing the amount of sand adhering to the casting surface after sand removal for each solid. The horizontal axis represents the casting number, and the vertical axis represents the amount of adhering sand. As shown in Fig. As shown in Figure 4, in casting number 1, where the solid was casting sand, the amount of adhering sand was approximately 2 grams, and in casting number 2, where the solid was also casting sand, the amount of adhering sand was approximately 6 grams. Thus, the sand only lightly adhered to the casting when the solid was casting sand. In comparison, in casting number 3, where the solid was natural quartz sand, the amount of adhering sand was approximately 36 grams, and in casting number 4, where the solid was also natural quartz sand, the amount of adhering sand was approximately 32 grams. The natural quartz sand solidified around the casting. Since natural quartz sand caused overfiring defects, the weight of natural quartz sand that could be removed from the casting with a metal file was measured.Thus, it was confirmed that it is difficult to achieve both the strength and collapse properties of the master mold when using natural quartz sand as the solid. Furthermore, it was confirmed that both the strength and collapse properties of the master mold can be achieved using casting sand as the solid. [Test 4: Assessment of collapsible properties]

[0053] The collapse properties of cores and master molds prepared using each binder were evaluated.

[0054] The parts by weight of each binder required to achieve a flexural strength of 3 MPa or more in Casting Sand 1, estimated from the results of Test 2, are shown in Table 7. Table 7 Binder 1 1.0 part by weight Binder 2 2.5 parts by weight Binder 3 1.5 parts by weight Binder 4 4.0 parts by weight <kern>(Examples 23 to 26)

[0055] In Example 23, a core was prepared using 100 parts by weight of casting sand 1, 1 part by weight of binder 1, and 0.25 part by weight of an anionic surfactant. In Example 24, a core was prepared using 100 parts by weight of casting sand 1, 2.5 parts by weight of binder 2, and 0.25 part by weight of an anionic surfactant. In Example 25, a core was prepared using 100 parts by weight of casting sand 1, 1.5 parts by weight of binder 3, and 0.5 part by weight of an anionic surfactant. In Example 26, a core was prepared using 100 parts by weight of casting sand 1, 4.0 parts by weight of binder 4, and 0.25 part by weight of an anionic surfactant. The machining conditions for Examples 23 to 26 were the same as in Example 1. <masterform>(Examples 27 to 30)

[0056] In Example 27, a master mold was prepared using 100 parts by weight of casting sand 1 and 1 part by weight of binder 1. In Example 28, a master mold was prepared using 100 parts by weight of casting sand 1 and 2.5 parts by weight of binder 2. In Example 29, a master mold was prepared using 100 parts by weight of casting sand 1 and 1.5 parts by weight of binder 3. In Example 30, a master mold was prepared using 100 parts by weight of casting sand 1 and 4.0 parts by weight of binder 4. The processing conditions for Examples 27 to 30 were the same as in Example 21. Table 8 Casting number r core Masterform solid Type of binder Binder (parts by weight) 5 Example 23 Example 23 Casting sand 1 Binder 1 1,0 6 Example 24 Example 20 Casting sand 1 Binder 2 2,5 7 Example 25 Example 19 Casting sand 1 Binder 3 1,5 8 Example 36 Example 20 Casting sand 1 Binder 4 4,0

[0057] Using the core and master mold from casting number 5, FC200 cast iron was cast. The casting was performed without applying any coating to the core and master mold. After casting, the sprue was hammered 10 times to remove the sand from the casting. The core collapse properties were visually inspected and the weight of sand adhering to the casting was measured. The same conditions were used to visually inspect the core collapse properties and measure the weight of sand adhering to the casting for casting numbers 6 to 8. <Visuelle Ergebnisse für die Kollabiereigenschaften der Kerne>

[0058] In the casting sand for casting numbers 5 to 8, the cores collapsed, and the core parts became through holes. Thus, it was confirmed that both the strength and collapse properties of the cores can be achieved using casting sand as the solid, regardless of the type of binder. <Am Gussteil anhaftender Sand>

[0059] Fig. Figure 5 is a graph showing the amount of sand adhering to the casting surface after sand removal for each binder. The horizontal axis represents the casting number, and the vertical axis represents the amount of adhering sand. As shown in Fig. As shown in Figure 5, in castings 5 to 8, where the solid was casting sand, the amount of adhering sand was 4 grams or less, regardless of the type of binder. Thus, it was confirmed that when the solid was casting sand, the sand only lightly adhered to the casting, regardless of the type of binder. Furthermore, it was confirmed that both the strength and collapse properties of the master mold could be achieved by using casting sand as the solid, regardless of the type of binder.

[0060] While various illustrative embodiments have been described above, the disclosure is not limited to the illustrative embodiments described above, and various omissions, substitutions, and modifications may be made.

[0061] Various illustrative embodiments included in this disclosure include the following: [Item 1] A mold forming method of forming a mold for producing iron castings, the mold forming method comprising: producing mixed sand using casting sand as a solid and a binder; filling a mold with the mixed sand; and solidification of the mixed sand filled into the mold. [Item 2] The mold forming process according to Item 1, wherein the casting sand contains 60% or more of alumina (Al2O3) and 40% or less of silicon dioxide (SiO2) and the binder is either sodium silicate or potassium silicate. [Item 3] The mold forming method according to item 1 or 2, wherein the binder has a molar ratio of 1.8 or more. [Item 4] The mold forming 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 solid. [Item 5] The mold forming method according to any one of items 1 to 4, wherein the casting sand is produced by a melting process or a sintering process. [Item 6] The mold forming method according to any one of items 1 to 5, wherein, during solidification, the mixed sand is solidified by a dehydration condensation reaction. [Item 7] The mold forming method according to any one of items 1 to 6, wherein the mixed sand is solidified using carbon dioxide (CO2) gas during solidification. [Item 8] The mold forming method according to any one of items 1 to 7, wherein the mixed sand is a foamed mixed sand containing at least one surface-active substance. [Item 9] Molding material for forming a mold for producing iron castings, the molding material containing casting sand as a solid, the casting sand containing 60% or more of aluminum oxide (Al2O3) and 40% or less of silicon dioxide (SiO2) and either sodium silicate or potassium silicate as a binder. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2014-527915

[0003] < / masterform> < / kern> < / masterform> < / kern>

Claims

[1] A mold forming method of forming a mold for producing iron castings, the mold forming method comprising: producing mixed sand using casting sand as a solid and a binder; filling a mold with the mixed sand; and solidification of the mixed sand filled into the mold. [2] The mold forming method according to claim 1, wherein the casting sand contains 60% or more of alumina (Al2O3) and 40% or less of silicon dioxide (SiO2), and the binder is either sodium silicate or potassium silicate. [3] The mold forming method according to claim 1 or 2, wherein the binder has a molar ratio of 1.8 or more. [4] The mold forming method according to claim 1 or 2, wherein the binder is 4 parts by weight or less based on 100 parts by weight of the solid. [5] The mold forming method according to claim 1 or 2, wherein the casting sand is produced by a melting process or a sintering process. [6] The mold forming method according to claim 1 or 2, wherein, in solidifying, the mixed sand is solidified by a dehydration condensation reaction. [7] The mold forming method according to claim 1 or 2, wherein in the solidification step, the mixed sand is solidified using carbon dioxide (CO2) gas. [8] The mold forming method according to claim 1 or 2, wherein the mixed sand is foamed mixed sand containing at least one surfactant. [9] A mold material for forming a mold for producing iron castings, the mold material containing casting sand as a solid, the casting sand containing 60% or more aluminum oxide (Al2O3) and 40% or less silicon dioxide (SiO2) and either sodium silicate or potassium silicate as a binder.

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