JP2016163892A - Method for manufacturing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a mold capable of having high strength and reducing the gas generation amount during molding by using a saccharide as a binder.SOLUTION: A binder coated refractory material 1, which is formed by coating a surface of a refractory aggregate with a solid coating layer containing the saccharide as a binder, is filled in a mold tool 2, the binder in the coating layer is solidified or hardened by heating the binder coated refractory material 1 with a steam blown in the mold tool 2, and thereby, a molding 3 in which the refractory aggregate is bound with the binder is molded in the mold tool 2. After the molding 3 is taken out from the mold tool 2, the mold is produced by applying heat treatment to the molding 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a mold using a binder-coated refractory.

  Conventionally, there are various types of mold manufacturing methods, and one of them is a shell mold method. The shell mold method is obtained by molding a refractory aggregate for molds such as silica sand by binding with a binder, and has excellent characteristics such as obtaining a mold with good dimensional accuracy. Has been used a lot.

  As the binder for the shell mold, a thermosetting resin such as a phenol resin is generally used. A fire-resistant aggregate and a thermosetting resin are mixed to form a thermosetting resin on the surface of the fire-resistant aggregate. A coated binder-coated refractory (abbreviated as RCS) is prepared, and the binder-coated refractory is filled in a heated mold to melt and cure the binder thermosetting resin. Therefore, the mold is made. The binder-coated refractory is a granular material that itself is smooth and has good fluidity. Therefore, the filling property into the mold is good, air transportation is possible, and handling is also good.

  When forming a mold using such a binder-coated refractory, a binder-coated refractory is filled in a mold heated to a high temperature of 250 to 350 ° C., and conduction heat transfer from the high-temperature mold. In general, it is performed by heating the binder-coated refractory, but when the phenol resin of the binder is heated at a high temperature, ammonia gas and the like are generated due to the rapid reaction. There is a problem of causing environmental degradation.

  Therefore, after filling the mold with the binder-coated refractory, steam is blown into the mold, and the binder-coated refractory in the mold is heated by the latent heat of vaporization or sensible heat of the mold, thereby A manufacturing method has been proposed (see, for example, Patent Document 1).

  Thus, when steam is blown into the mold and the binder-coated refractory is heated, the entire binder-coated refractory in the mold can be instantaneously heated with the water vapor filled in the mold. The mold can be stably formed in a short time without the need to heat the mold to a high temperature, and even if ammonia gas is generated, it is absorbed into water vapor and prevented from being released into the atmosphere. Is something that can be done.

  However, when casting is performed by pouring the molten metal into the mold thus formed, the phenol resin of the binder is decomposed by the high-temperature action of the molten metal, for example, phenol, xylenol, toluene, benzene, methane, etc. are released. There is a problem of deteriorating the working environment. This problem cannot be avoided as long as a thermosetting resin such as a phenol resin is used as the binder for the binder-coated refractory.

  Furthermore, phenol resin has high heat resistance and a large amount of residual carbon. Therefore, when casting a casting by injecting molten metal into the mold, it is difficult for the mold to collapse due to the heat of the molten metal, and the casting is removed from the mold. In addition, it is necessary to apply an impact to the mold or to decompose the phenol resin by heating at a high temperature for a long time, and there is a problem that it takes time and effort to remove the mold.

  Therefore, the present applicant has proposed to use saccharides as a binder for a binder-coated refractory (see, for example, Patent Document 2). That is, when using a binder coated refractory coated with a solid coating layer containing a saccharide as a binder, filling the mold with this binder coated refractory, and then blowing water vapor into the mold Since the condensed water of water vapor is replenished to the binder-coated refractory in the mold, the moisture gives the sugars stickiness. Subsequently, the binder coated refractory can be heated in the mold to solidify the binder, and a mold in which the refractory aggregate is bonded with the solidified sugar binder is formed. Is something that can be done.

  When casting by casting molten metal into a mold having such a saccharide as a binder, the saccharide releases carbon dioxide and water when it is thermally decomposed, and releases toxic gas. Therefore, there is no possibility of deteriorating the work environment. Saccharides are easily decomposed by heat, and a mold having good disintegration that can be easily disintegrated by the heat of the molten metal can be obtained.

JP 2000-61583 A Special table 2011-030795 gazette

  As described above, a mold using a saccharide as a binder has characteristics that a toxic gas is not released at the time of casting and has a good disintegration property, but has a problem in terms of mold strength and heat resistance. Met.

  That is, when water vapor is blown into a mold filled with a binder-coated refractory, moisture is replenished as a condensed water to the saccharide on the surface of the binder-coated refractory, and this moisture imparts adhesiveness to the saccharide. . And, for example, by heating with steam that is blown continuously, the moisture in the mold is evaporated and moisture is removed from the saccharide, and the saccharide is changed from an adhesive state containing moisture to a dried and solidified state. A mold can be formed by bonding a refractory aggregate with solidified saccharides. Accordingly, since the refractory aggregate is only held in a state of being bonded by the dried and solidified saccharide, there is a problem that the strength and heat resistance of the mold are insufficient, and there is a possibility that the mold may be broken when the molten metal is poured into the mold. was there.

  In addition, molds using saccharides as a binder do not release toxic gases during casting, but carbon dioxide and water are often generated as pyrolysis gases, so gas defects are likely to occur in castings during casting, which increases yield. Also had problems.

  The present invention has been made in view of the above points, and aims to produce a mold that uses saccharides as a binder and has high strength and heat resistance and can reduce the amount of gas generated during casting. To do.

  The method for producing a mold according to the present invention comprises filling a mold 2 with a binder coated refractory 1 formed by coating the surface of a refractory aggregate with a solid coating layer containing saccharide as a binder. , By blowing water vapor into the mold 2 and heating the binder-coated refractory 1, the binder of the coating layer is solidified or cured, thereby forming the molded article in which the refractory aggregate is bonded with the binder. 3 is molded in the mold 2, and after the molded product 3 is taken out of the mold 2, the molded product 3 is heat-treated.

  By using the binder-coated refractory 1 formed by coating a solid coating layer containing saccharide as a binder as described above, it is formed by combining a refractory aggregate with saccharide as a binder. The saccharides can only produce carbon dioxide and water when decomposed by heating, and no toxic gases are released, and there is no risk of polluting the environment. Saccharides are easily decomposed by heat, and a mold having good disintegration can be obtained.

  Then, water vapor is blown into the mold 2 filled with the binder-coated refractory 1 to solidify or harden the binder, thereby forming the mold 3 in which the refractory aggregate is bonded with the binder. When the molded product 3 molded with saccharide as a binder is used as it is as a mold, the strength and heat resistance are insufficient. However, the molded product 3 is taken out from the mold 2 and molded. Heat treatment of the product 3 generates water from the saccharide molecules and evaporates to cause condensation polymerization. This increases the bonding strength of the refractory aggregate by the saccharide and improves the heat resistance of the saccharide. A mold having high properties can be obtained, and moreover, since water is removed from the saccharide molecules, the amount of decomposition gas generated during casting is reduced.

Further, the present invention is characterized in that the heat treatment of the molded product is performed at a temperature of 100 to 350 ° C.
Is.

  By setting the heat treatment temperature of the molded product 3 within this range, the binding force due to the saccharide can be sufficiently increased.

  Further, the present invention is characterized in that the molded product is heat-treated for 10 to 200 minutes.

  By setting the heat treatment time of the molded product 3 within this range, the binding force due to the saccharide can be sufficiently increased.

  Further, the present invention is characterized in that the molded product 3 taken out from the mold 2 is heat-treated in a heat treatment container 4.

  By using the heat treatment container 4 that is easy to set the temperature, the molded product 3 can be heat treated at an arbitrary temperature as required.

  The present invention also provides adhesiveness to the saccharide of the binder by blowing steam into the mold 2 filled with the binder-coated refractory 1 and supplying condensed water of the steam into the mold 2. Subsequently, the binder coated refractory 1 is heated by condensation latent heat and sensible heat of water vapor blown into the mold 2 to solidify or cure the binder.

  When steam is blown into the mold 2, the condensed water generated when the steam contacts the binder-coated refractory 1 and is deprived of heat is supplied to the binder. It is moistened with this condensed water to give stickiness, and the refractory aggregate can be bonded with this adhesive force of saccharides, and then the water supplied to the binder is evaporated and condensed with the latent heat of condensation of steam and sensible heat. The agent can be solidified or cured, and the molding in the mold 2 can be performed efficiently.

  Further, the present invention is characterized in that heating of the binder-coated refractory 1 in the mold 2 is performed by water vapor blown into the mold 2 and a heated gas blown into the mold 2 following this water vapor. It is what.

  By blowing water vapor into the mold 2 filled with the binder-coated refractory 1, the temperature of the binder-coated refractory 1 can be rapidly increased to near 100 ° C. by the condensation latent heat and sensible heat of the water vapor. At the same time, by blowing a heated gas into the mold 2, the condensed water can be quickly evaporated with this gas having a small amount of water, and the temperature can be raised to 100 ° C. or higher in a short time. Yes, it is possible to increase the speed at which the temperature in the mold 2 is increased to a temperature higher than the temperature at which the binder of the binder coated refractory 1 solidifies or cures. It can be performed efficiently.

  As this heated gas, heated air or a mixed gas of water vapor and air can be used.

  Furthermore, in the present invention, as the water vapor, superheated water vapor can be used in addition to the saturated water vapor.

  In the present invention, the coating layer of the binder-coated refractory 1 contains carboxylic acid.

  The saccharide can be polymerized by the carboxylic acid, and the strength of the template and the heat resistance can be further improved by further increasing the binding force of the saccharide.

  In the present invention, the coating layer of the binder-coated refractory 1 contains a thermosetting resin in addition to sugar as a binder.

  The thermosetting resin can reinforce the bonding strength of the refractory aggregate, and the mold strength and heat resistance can be further improved. As this thermosetting resin, a phenol resin is preferable.

  At this time, the content of the thermosetting resin in the binder is preferably 80% by mass or less.

  In the present invention, the binder-coated refractory 1 is filled in the mold 2 and water is supplied into the mold 2 to impart adhesiveness to the saccharide of the binder, and then in the mold. The binder is solidified or cured by blowing superheated steam and heating the binder-coated refractory 1 with the condensation latent heat and sensible heat of the superheated steam.

  Thus, by first supplying water into the mold 2 and moistening the binder, the saccharide can be made sticky, and the refractory aggregate can be bonded with the saccharide's adhesive force, and then dried. By blowing superheated steam, which is steam, the water in the mold 2 can be efficiently evaporated, and the temperature of the binder-coated refractory 1 can be efficiently increased to solidify or cure the binder. Therefore, the molding in the mold 2 can be performed efficiently.

  In addition, the present invention provides adhesive to the saccharide by filling the binder-coated refractory material 1 into the mold 2, blowing saturated steam into the mold 2 and supplying condensed water vapor to the binder. Then, the binder is solidified or cured by blowing superheated steam into the mold 2 and heating the binder-coated refractory 1 with the condensation latent heat and sensible heat of the superheated steam. It is.

  Thus, by first blowing saturated steam into the mold 2, the condensed steam condensed water with a large amount of moisture imparts adhesiveness to the saccharide of the binder, and the refractory aggregate is bonded with the adhesive strength of the saccharide. Next, by blowing superheated steam, which is dry steam, into the mold 2, moisture in the mold 2 can be efficiently evaporated, and the binder-coated refractory 1 of the binder-coated refractory 1 can be efficiently evaporated. The binder can be solidified or cured by raising the temperature, and the molding in the mold 2 can be performed efficiently.

  According to the present invention, by using a binder coated refractory 1 formed by coating a solid coating layer containing saccharide as a binder, a refractory aggregate is bound using saccharide as a binder. A mold can be manufactured, and saccharides release carbon dioxide and water when thermally decomposed, and do not release toxic gases, and there is no risk of polluting the environment. Saccharides are easily decomposed by heat, and a mold having good disintegration can be obtained. Then, water vapor is blown into the mold 2 filled with the binder-coated refractory 1 to solidify or harden the binder, thereby forming the mold 3 in which the refractory aggregate is bonded with the binder. When the molded product 3 molded with saccharide as a binder is used as it is as a mold, the strength and heat resistance are insufficient. However, the molded product 3 is taken out from the mold 2 and molded. By heat-treating at a temperature higher than the heating temperature in the mold 2, the binding strength of the refractory aggregate by the saccharide is increased, the heat resistance of the saccharide is improved, and a mold having high strength and heat resistance can be obtained. In addition, since water is removed from the saccharide molecules, the amount of cracked gas generated during casting is reduced.

1 shows a steam heating type mold used in an example of an embodiment of the present invention. 1 shows a heat treatment container used in an example of an embodiment of the present invention. It is a graph which shows the test result of the heat resistance of saccharides.

  Embodiments of the present invention will be described below.

  The binder-coated refractory 1 used in the present invention is formed by coating the surfaces of refractory aggregate particles with a solid coating layer containing a binder.

  The refractory aggregate is not particularly limited, but can be exemplified by silica sand, mountain sand, alumina sand, olivine sand, chromite sand, zircon sand, mullite sand, and other artificial sand, These may be used alone, or may be used in combination by mixing a plurality of types. The artificial sand can be exemplified by artificially made sand containing calcia, magnesia, alumina and the like, and can be exemplified by artificially made sand by crushing stones and rocks. In other words, the artificial sand may be any commonly used artificially produced sand.

  In addition, monosaccharides, oligosaccharides, and polysaccharides can be used as the saccharides. Among various monosaccharides, oligosaccharides, and polysaccharides, one type is selected and used alone, or a plurality of types are selected and used in combination. You can also.

  Although it does not specifically limit as monosaccharide used in this invention, Glucose (glucose), fructose (fructose), galactose, etc. can be mentioned.

  Examples of oligosaccharides include disaccharides such as maltose (malt sugar), sucrose (sucrose), lactose (lactose), and cellobiose.

  Furthermore, examples of the polysaccharide include starch sugar, dextrin, xanthan gum, curdlan, pullulan, cycloamylose, chitin, cellulose, starch, and the like. One type selected from these can be used, and a plurality of types can be used in combination. Here, examples of the starch include powdered starch and processed starch. Specifically, raw starch such as potato starch, corn starch, high amylose, sweet potato starch, tapioca starch, sago starch, rice starch, amaranth starch, and these modified starches (roasted dextrin, enzyme-modified dextrin, acid-treated starch, Oxidized starch, dialdehyde starch, etherified starch (carboxymethyl starch, hydroxyalkyl starch, cationic starch, methylolated starch, etc.), esterified starch (acetic acid starch, phosphate starch, succinate starch, octenyl succinic acid starch, maleic acid Starch, higher fatty acid esterified starch, etc.), cross-linked starch, kraft starch, wet heat-treated starch, etc. Among these, roasted dextrin, Containing modified dextrin, acid-treated starches, those low molecular weight as oxidized starch, and low viscosity, such as cross-linked starch starches are preferred.

  Furthermore, cereal seed powder containing sugars can also be used as a binder. Examples of cereal seed powder containing sugars include wheat flour, rice flour, and corn flour.

  The coating layer of the binder-coated refractory 1 may contain a carboxylic acid that polymerizes a saccharide, particularly a polysaccharide. As the carboxylic acid, a monovalent carboxylic acid or a divalent or higher polyvalent carboxylic acid can be used. Examples of the monovalent carboxylic acid include benzoic acid, salicylic acid, anthranilic acid, and the like, and examples of the polyvalent carboxylic acid include oxalic acid, maleic acid, succinic acid, citric acid, fumaric acid, malic acid, tartaric acid. , Isophthalic acid, itaconic acid, butanetetradicarboxylic acid, methyl vinyl ether-maleic anhydride copolymer, and the like. A monovalent carboxylic acid mainly acts as a reaction accelerator (curing accelerator, curing catalyst), and a polyvalent carboxylic acid mainly acts as a cross-linking agent (curing agent) to polymerize saccharides. is there. A saccharide can be polymerized by polymerizing it by the action of a carboxylic acid, and in some cases it can be cured. These carboxylic acids can be used alone or in combination of two or more.

  The blending amount of the carboxylic acid varies depending on the type of saccharide, and is not particularly limited. However, it is preferably set in a range of 1 to 40 parts by weight of the carboxylic acid with respect to 100 parts by weight of the saccharide. A range of 1 to 30 parts by mass is particularly preferable. If the amount of carboxylic acid is too small, it is difficult to polymerize saccharides to a sufficient molecular weight. Moreover, even if it mix | blends more carboxylic acid than this, since the effect of making saccharides into a polymer is not improved, there exists a possibility that it may become economically disadvantageous. In addition, it is preferable to mix the carboxylic acid with saccharides in a state of being dissolved in water in advance in order to exert a high effect as a curing agent.

  In the present invention, saccharides are used as the binder contained in the coating layer of the binder-coated refractory 1, but the thermosetting resin is used in combination with the saccharide as the binder, and the coating layer You may make it contain. By using a thermosetting resin as a binder, the bond strength of the refractory aggregate by the binder can be increased, and the strength and heat resistance of the mold are improved compared to the case of using saccharide alone as the binder. Is something that can be done. Particularly, since the effect of improving the heat resistance of the mold is high, it is suitable for casting using a high-temperature molten metal.

  The content of the thermosetting resin in the coating layer is preferably set to 80% by mass or less, more preferably 50% by mass or less, with respect to the total amount of saccharide and thermosetting resin. When there is more content of a thermosetting resin than this, the effect by using saccharides as a binder will become inadequate.

  Although this thermosetting resin used together with saccharides as a binder is not particularly limited, a resol-type or novolac-type phenol resin can be used. A resol type phenol resin and a novolac type phenol resin may be used alone or in combination. Moreover, what made saccharides and phenols react beforehand can also be used. The state before coating the fireproof aggregate with the thermosetting resin as a binder may be either liquid or solid.

  The coating layer of the binder-coated refractory 1 may contain a lubricant in the coating layer in order to improve the fluidity of the binder-coated refractory. Examples of lubricants include aliphatic hydrocarbon lubricants such as paraffin wax and carnauba wax, higher aliphatic alcohols, aliphatic amide lubricants such as ethylenebisstearic acid amide and stearic acid amide, metal soap lubricants, fatty acid ester lubricants. A composite lubricant or the like can be used, and among them, a metal soap-based lubricant is preferable. As the metal soap-based lubricant, calcium stearate, barium stearate, zinc stearate, aluminum stearate, magnesium stearate, or a combination of these can be used.

  And by adding and mixing saccharides, if necessary, thermosetting resins such as carboxylic acids and phenol resins, reaction products of saccharides and phenols, lubricants, etc., into the refractory aggregate particles, the refractory aggregate The binder coated refractory 1 used in the present invention can be obtained by coating a coating layer containing a binder mainly composed of sugars on the surface of the binder.

  The amount of the coating layer to be coated on the refractory aggregate differs depending on the components and applications, and cannot be specified unconditionally. Is generally preferred to be in the range of 0.02 to 0.15 parts by mass in solid content. When the binder exceeds 5.0 parts by mass with respect to 100 parts by mass of the refractory aggregate, kneading of the refractory aggregate and the binder becomes difficult. Moreover, when the binder is less than 0.5 parts by mass with respect to 100 parts by mass of the refractory aggregate, it is difficult to maintain the strength of the mold.

  Examples of the method for preparing the binder-coated refractory 1 by coating the surface of the refractory aggregate with a coating layer include a hot coat method, a cold coat method, a semi-hot coat method, and a powder solvent method.

  In the hot coating method, a solid binder is added to and mixed with a refractory aggregate heated to 110 to 180 ° C., and the solid binder is melted by heating with the refractory aggregate. In this method, the surface of the refractory aggregate is wetted and coated, and then cooled with the mixture kept, thereby obtaining a granular and free-flowing binder-coated refractory. Alternatively, a method for obtaining a binder-coated refractory by mixing a refractory aggregate heated to 110 to 180 ° C. with a binder that is dissolved or dispersed in a solvent such as water and coating the mixture to volatilize the solvent. It is.

  In the cold coating method, the binder is dispersed or dissolved in a solvent such as water or methanol to form a liquid, which is added to and mixed with the refractory aggregate particles, and the solvent is volatilized to coat the binder. It is a method of obtaining a refractory.

  In the semi-hot coating method, the binder dispersed or dissolved in the above solvent is added to and mixed with the particles of the refractory aggregate heated to 50 to 90 ° C., and the solvent is volatilized to cause the binder coated refractory. Is the way to get.

  In the powder solvent method, a solid binder is pulverized, this pulverized binder is added to the refractory aggregate particles, and a solvent such as water or methanol is added and mixed to volatilize the solvent. To obtain a binder-coated refractory.

  In any of the above methods, the surface of the refractory aggregate can be coated with a solid coating layer at room temperature (30 ° C.), and can be obtained in a granular manner to obtain a binder-coated refractory having fluidity. In view of workability, the hot coating method is preferable. In addition, when mixing the binder with the refractory aggregate as described above, various coupling agents such as a curing agent and a silane coupling agent for making the refractory aggregate and the binder compatible with each other, Moreover, carbonaceous materials, such as graphite, can also be mix | blended.

  When a saccharide and a thermosetting resin are used in combination as a binder, a method for forming a coating layer in which a saccharide and a thermosetting resin are mixed by simultaneously coating the saccharide and the thermosetting resin on a refractory aggregate; There is a method of forming a coating layer having a two-layer structure by coating the surface of the material with a thermosetting resin and then coating with saccharides, and any method may be used.

  Next, a method for producing a mold using the binder-coated refractory 1 prepared as described above will be described. First, the binder-coated refractory 1 is filled in the mold 2 and steam is blown into the mold 2 to heat the binder-coated refractory 1 with the condensation latent heat and sensible heat of the water vapor. A molded product 3 in which the refractory aggregate is bonded with a binder is molded in the mold 2.

  That is, when water vapor is blown into the mold 2 filled with the binder-coated refractory 1, the water vapor is first brought into contact with the binder-coated refractory 1 to generate heat and condensed water is generated. Then, when condensed water acts on the binder of the coating layer of the binder coated refractory 1, the saccharide in the solid state in the binder absorbs this condensed water and swells and gelatinizes, thereby binding the binder. Becomes wet and becomes sticky, and the refractory aggregate of the binder coated refractory 1 is bound by this stickiness of sugars. When steam is continuously blown into the mold 2, the binder-coated refractory 1 is heated by the condensation latent heat and sensible heat of the steam subsequently blown into the mold 2, and the moisture acting on the binder is evaporated and dried. The saccharide of the binder can be solidified or cured. In this manner, a molded product 3 in which the refractory aggregate of the binder-coated refractory 1 is bonded with a solid binder obtained by solidifying or curing can be molded in the mold 2.

  In this way, when the binder of the coating layer of the binder coated refractory 1 is molded by heating with water vapor, the saccharide contained as the binder is a toxic gas when heated to solidify or harden. Therefore, it is possible to perform molding without polluting the environment.

  Here, it is possible to use the molded product 3 obtained in this way as a mold as it is, but since this molded product 3 is formed by using saccharides as a binder, it can be used as a mold. Often lack strength and heat resistance. Therefore, in the present invention, the molded product 3 is taken out from the mold 2, the molded product 3 is heat-treated, and the molded product 3 after the heat treatment is used as a mold.

  The temperature of the heat treatment is preferably 100 ° C. or higher, and more preferably 150 ° C. or higher. If the temperature of the heat treatment is lower than this, the effect of heat-treating the molded product 3 cannot be sufficiently obtained. On the other hand, if the temperature of the heat treatment is too high, the saccharide may be thermally decomposed. Therefore, the temperature is preferably 350 ° C. or lower, more preferably 300 ° C. or lower, and particularly preferably 240 ° C. or lower. Moreover, although the time of heat processing changes with the magnitude | sizes of the molded object 3 shape | molded as a casting_mold | template, it is preferable that it is 10 minutes or more, and it is more preferable that it is 30 minutes or more. If the heat treatment time is shorter than this, the effect of heat-treating the molded product 3 cannot be sufficiently obtained. On the other hand, if the heat treatment time is too long, the sugar may be deteriorated particularly when the heat treatment temperature is high. Therefore, the heat treatment time is preferably 200 minutes or less, more preferably 80 minutes or less.

  When the molded product 3 is heat-treated in this way, the molecular structure of the binder saccharide is changed by the action of heat. For example, when sugar is heated, it becomes syrup at 103-105 ° C, fondant at 107-115 ° C, caramel at 115-121 ° C, toffee at 140 ° C, drops at 145 ° C, lime at 165 ° C, It is considered that water is generated from the saccharide molecules and dehydrated so as to change into caramel sauce at 180 ° C. and caramel at 190 ° C., and the saccharide molecules undergo a condensation reaction. For this reason, the molecular weight of the saccharide is increased, the force for binding the refractory aggregate using the saccharide as a binder is increased, the heat resistance of the saccharide is improved, and the molded product 3 is obtained by heat treatment. The strength and heat resistance of the mold can be increased.

  Casting can be performed by pouring a high-temperature molten metal into the mold manufactured as described above and casting the casting. At this time, the binder binding the refractory aggregate of the mold is decomposed by the high-temperature action of the molten metal, but water and carbon dioxide gas are generated even if the saccharides constituting the binder are decomposed. There is no generation of harmful gas, and it does not deteriorate the environment of the casting site. In addition, since the binder saccharide bonded to the refractory aggregate of the mold is thermally decomposed at a relatively low temperature, it is easily decomposed by the heat of the molten metal. Therefore, the mold can be easily disintegrated, and it is not necessary to apply an impact to the mold or to decompose the binder by heating at a high temperature for a long time in order to remove the casting from the mold. The work of removing the casting from the mold can be easily performed.

  In addition, the binder that binds the refractory aggregate of the mold is composed of saccharides, but the heat treatment increases the bonding strength of the refractory aggregate by the saccharides and improves the heat resistance of the saccharides. And heat resistance is improved. Therefore, for example, even when a large amount of molten metal is poured into the mold, the mold is not broken, and it is possible to prevent an accident that the mold is broken when it is poured into the mold.

  Here, when a thermosetting resin such as a phenol resin is used in addition to saccharides as a binder as described above, the bonding strength of the refractory aggregate can be increased by the thermosetting resin having high heat resistance. The strength and heat resistance of the mold can be further improved.

  As described above, by using a thermosetting resin such as a phenol resin as a binder, a mold having high strength and heat resistance can be obtained. When pouring hot water, harmful gases may be generated, and the disintegration property of the mold is also lowered. For this reason, when using together thermosetting resins, such as a phenol resin, it is set to the quantity of 80 mass% or less with respect to the whole quantity of binder as stated above, and should be 50 mass% or less. Is more preferable. Moreover, in order to obtain the effect by using a thermosetting resin as a binder, the thermosetting resin is preferably 10% by mass or more based on the total amount of the binder, and a high effect by the combination is obtained. For this purpose, the thermosetting resin is more preferably 25% by mass or more based on the total amount of the binder.

  Next, a specific example of mold production will be described with reference to FIGS. FIG. 1 shows an example of an apparatus for forming a molded product 3 using water vapor. As shown in FIG. 1A, an injection port 7 is provided on the upper surface of a mold 2 formed by providing a cavity 6 therein, and a discharge port closed by a net 8 such as a metal mesh on the lower surface of the mold 2. 9 is provided. This mold 2 can be divided vertically or horizontally. The binder coated refractory 1 is stored in a hopper 10, and an air supply pipe 12 with a cock 11 is connected to the hopper 10. Then, after aligning the nozzle 13 at the lower end of the hopper 10 with the inlet 7 of the mold 2, the cock 11 is switched from the closed state to the open state, whereby air is blown into the hopper 10 to pressurize it. The binder-coated refractory 1 is blown into the mold 2, and the binder-coated refractory 1 is filled into the cavity 6 of the mold 2. Since the discharge port 9 is blocked by the net 8, the binder-coated refractory 1 does not leak from the discharge port 9. When a plurality of injection ports 7 and discharge ports 9 are provided in the mold 2 as in the embodiment of FIG. 1, the binder-coated refractory 1 is inserted from one or more of the plurality of injection ports 7. That's fine.

  Here, since the coating layer of the binder-coated refractory 1 coated with the refractory aggregate is made of a solid binder, the binder-coated refractory 1 has no adhesiveness on the surface. Good fluidity. Therefore, when the binder-coated refractory 1 is filled in the mold 2 as described above, the binder-coated refractory 1 can be smoothly poured into the cavity 6 of the mold 2, and the mold has good filling properties. 2 can be filled with the binder-coated refractory 1, and it is possible to prevent poor filling.

  After filling the mold 2 with the binder-coated refractory 1, the hopper 10 is removed from the inlet 7 of the mold 2 and an air supply pipe is connected to each inlet 7 as shown in FIG. 14 is connected. Water vapor and heated gas can be selectively supplied to the air supply pipe 14. The cock 15 of the air supply pipe 14 is opened, and water vapor is first blown into the cavity 6 of the mold 2.

  And when water vapor | steam is blown in in this way in the shaping | molding die 2, in an initial stage of blowing water vapor | steam, since water vapor | steam contacts the surface of the binder coated refractory 1, latent heat from water vapor | steam is binder-coated refractory 1 As a result, water vapor is condensed and condensed water is generated on the surface of the binder-coated refractory 1. Since the binder of the coating layer on the surface of the binder-coated refractory 1 is solid, the binder-coated refractory 1 cannot be bonded to each other as it is, but the binder-coated refractory 1 is thus bonded. When condensed water is supplied to the surface of the product 1, the saccharide in the solid state in the binder absorbs this condensed water and swells to form a paste, and the binder becomes wet and causes stickiness. . As a result, the binder-coated refractory 1 can be bonded with the adhesiveness of the binder of the surface coating layer.

  Next, the binder-coated refractory 1 is heated by the condensation latent heat and sensible heat of the steam blown into the mold 2. Since water vapor has high latent heat and sensible heat, the temperature of the binder-coated refractory 1 rapidly rises to around 100 ° C. by this latent heat transferred when the water vapor condenses. Thus, the time during which the binder-coated refractory 1 is heated to near 100 ° C. by the heat transfer of the latent heat of water vapor is the temperature of the water vapor, the flow rate of blowing into the mold 2, and the binder in the mold 2. Although it varies depending on the filling amount of the coated refractory 1, it is usually a short time of about 3 to 30 seconds. The water vapor blown into the mold 2 from the inlet 4 is exhausted from the outlet 9 after heating the binder-coated refractory 1 in the mold 2. At this time, moisture acting on the binder on the surface of the binder-coated refractory 1 can be evaporated and dried, and the saccharide of the binder can be solidified or cured. In this way, the molded product 3 in which the refractory aggregate of the binder coated refractory 1 is bonded with the solidified or hardened binder can be molded in the mold 2.

  Alternatively, after the temperature of the binder-coated refractory 1 has risen to around 100 ° C., the supply to the air supply pipe 14 may be switched to the heated gas, and the heated gas may be blown into the mold 2. The heated gas only needs to have a moisture content lower than that of the water vapor, and heated air can be used. For example, air in the atmosphere may be heated and supplied to the air supply pipe 14 as a heated gas. Moreover, this mixed gas can also be used as heating gas by mixing heated air with said water vapor | steam and making a moisture content low. The temperature of the heated gas is not particularly limited and may be 100 ° C. or higher and higher than the temperature at which the binder of the binder coated refractory 1 is solidified or cured. The upper limit of temperature should just be below the temperature which decomposes | disassembles a binder, and is not set in particular.

  When steam is blown into the mold 2 as described above, the temperature of the binder-coated refractory 1 can be rapidly increased to around 100 ° C. by the latent heat transferred when the steam condenses. In order to raise the temperature to 100 ° C. or higher, it is necessary to evaporate the condensed water on the surface of the binder-coated refractory 1. And this condensed water is evaporated by the heating by the water vapor | steam blown in after that, but as above-mentioned, since water vapor | steam contains many water | moisture contents, the efficiency which evaporates condensed water is low. Therefore, the heated gas is blown into the mold 2 as described above. Since the heated gas is a dry gas having a lower moisture content and lower humidity than water vapor, it is generated in the mold 2. The condensed water can be evaporated and dried in a short time. Here, when the water evaporation experiment was performed with the air flow of water vapor and heated air, the evaporation of water into the heated air may be larger than the evaporation rate of water into the water vapor when the temperature is around 170 ° C. or lower. (T. Yosida, Hyodo, T., Ind. Eng. Chem. Process Des. Dev., 9 (2), 207-214 (1970)). As seen in this report, the heated gas is blown into the mold 2 so that the condensed water can be evaporated and dried in a shorter time than when steam is continuously blown.

  Accordingly, the temperature of the binder-coated refractory 1 can be raised to 100 ° C. or more in a short time after the heated gas starts to be blown into the mold 2. The speed at which the temperature in the mold 2 is increased to a temperature equal to or higher than the temperature at which the agent solidifies or hardens can be increased. As a result, the molded product 3 can be molded in a short heating time.

  The time for blowing the heated gas into the mold 2 includes the temperature of the heated gas, the flow rate of blowing into the mold 2, the filling amount of the binder-coated refractory 1 in the mold 2, and the condensed water in the mold 2. Although it varies depending on the amount, it is usually a short time of about 5 to 60 seconds. Therefore, it is possible to mold the molded product 3 in a short time of about 10 seconds to 1 minute from when the steam is started to be blown into the mold 2 until the heated gas is completely blown.

  Here, as the steam blown into the mold 2, saturated steam can be used as it is, but superheated steam can also be used. Superheated steam is water vapor in a complete gas state that is further heated to saturated boiling water to a temperature equal to or higher than the boiling point, and is dry steam at 100 ° C. or higher. The superheated steam obtained by heating the saturated steam may be one that is expanded at a constant pressure without increasing the pressure, or may be pressurized steam that is increased without increasing the pressure. The temperature of the superheated steam blown into the mold 1 is not particularly limited, and the temperature of the superheated steam can be increased up to about 900 ° C. Therefore, if the temperature is set between 100 and 900 ° C. as necessary. Good. Since the superheated steam is thus a high-temperature dry steam, it is possible to eliminate the need to use the heated gas as described above.

  As described above, it is necessary to make the binder of the binder-coated refractory 1 wet with moisture at the initial stage of blowing steam into the mold 2. At this time, even when superheated steam is used as the steam, the temperature of the binder-coated refractory 1 before the steam is blown is lower than that of the superheated steam. The latent heat is taken away by the binder-coated refractory 1, and condensed water is generated from the superheated steam, and the binder of the binder-coated refractory 1 can be wetted by this condensed water. However, when superheated steam is used as the steam, the generation of condensed water is insufficient, and the binder of the binder-coated refractory 1 cannot be uniformly moistened at the initial stage of blowing the steam into the mold 2. There is.

  In such a case, it is preferable to supply moisture to the surface of the binder-coated refractory 1 at the initial stage of blowing the steam into the mold 2. For example, at the initial stage of the step of blowing water vapor into the mold 2, saturated water vapor is supplied to the air supply pipe 14 and saturated water vapor is blown into the mold 2 from the air supply pipe 14. Since the condensed water is easily generated from the saturated steam, the condensed water generated from the saturated steam in the mold 2 can be supplied to the binder-coated refractory 1 as moisture. The binder of the agent coated refractory 1 can be uniformly moistened. Thereafter, the supply to the air supply pipe 14 is switched from saturated steam to superheated steam, and the superheated steam is blown into the mold 2 from the air supply pipe 14. At this time, it is desirable to set the ratio of the time for blowing saturated water vapor and the time for blowing superheated water vapor to a range of about 1: 9 to 5: 5.

  In the above embodiment, the condensed water of steam blown into the mold 2 is supplied to the surface of the binder-coated refractory 1 so that the binder becomes wet with the moisture of the condensed water. After filling the mold 2 with the binder-coated refractory 1, water may be injected into the mold 2 to supply moisture to the binder-coated refractory 1. For example, after filling the mold 2 with the binder-coated refractory 1, water is injected into the mold 2 from the injection port 7, and the binder of the binder-coated refractory 1 is wet with this water. After that, there is a method in which water vapor is blown from the injection port 7. Excess water injected into the mold 2 is discharged from the discharge port 9 by blowing the water vapor. Thus, if moisture is supplied into the mold 2 filled with the binder-coated refractory 1 to moisten the binder, the steam is superheated as steam from the beginning of the step of blowing water vapor into the mold 2. Water vapor can be used.

  Further, as shown in FIGS. 1 (a) to (b), when the binder-coated refractory 1 is filled in the cavity 6 of the mold 2, the binder-coated refractory 1 is heated in advance. The preheated binder-coated refractory 1 may be supplied to the mold 2 and filled in the cavity 6. By preheating the binder-coated refractory 1 in this way, the temperature drop of water vapor blown into the mold 2 can be suppressed, and the temperature at which the binder of the coating layer is dried and solidified is exceeded. The speed at which the temperature inside the mold is raised can be increased, and the time for molding the molded product 3 can be shortened.

  The preliminary heating of the binder-coated refractory 1 can be performed, for example, in a hopper 10 that stores the binder-coated refractory 1. The temperature at which the binder-coated refractory 1 is preheated is not particularly limited, but is preferably in the range of about 30 to 100 ° C.

  As described above, the molded product 3 can be molded in the molding die 2 by blowing water vapor into the molding die 2 filled with the binder-coated refractory 1. Then, the mold 2 is opened, the molded product 3 is taken out, and the molded product 3 is put in a heat treatment container 4 and heat treated.

  FIG. 2A shows an example of the heat treatment container 4, which is formed by providing a heat generating means 18 in the container body 17, and an opening 20 with a door 19 is formed on the front surface of the container body 17. The heating means 18 is provided on the side wall of the container body 17 or the like. The heating means 18 may be anything as long as it can heat the inside of the heat treatment container 4 by self-heating by combustion or electric resistance, for example, a gas burner, an electric heater or the like can be used. For example, the heat treatment container 4 can be formed by a hot air circulation dryer.

  FIG. 2B shows another example of the heat treatment container 4. The inlet 21 through which water vapor is blown into the container body 17 is at the lower part, and the exhaust port 22 through which water vapor is discharged from the container body 17 is at the upper part. Is provided. By closing the opening 20 on the front surface of the container body 17 with a door 19, the inside of the heat treatment container 4 is sealed except for the inlet 21 and the exhaust port 22. A steam generator 23 is connected to the inlet 21. The steam generator 23 is formed by including a boiler and a superheater, and heats water in the boiler to generate water vapor (saturated water vapor) and further heats the water vapor in the superheater to form a heat treatment container as superheated steam. 4 is supplied.

  Then, the molded product 3 molded with the molding die 2 as described above is placed in the heat treatment container 4, and the molded product 3 is heated in the heat treatment container 4 at a predetermined temperature for a predetermined time to obtain a mold. It is something that can be done. Here, in the heat treatment container 4 of FIG. 2A, the molded product 3 can be heat treated at an accurate temperature by setting the inside of the heat treatment container 4 to a predetermined temperature in advance by the heating means 18. Further, in the heat treatment container 4 of FIG. 2B, the molded product 3 can be heat-treated with superheated steam with high thermal efficiency, and the heat treatment time can be shortened.

  Next, the present invention will be specifically described with reference to examples.

(Production example of binder coated refractory)
10 kg of flattery silica sand heated to 140 ° C. was placed in a whirl mixer, and an aqueous solution in which saccharides shown in Table 1 were dissolved or dispersed in 450 g of water was added and kneaded for about 90 seconds. At this time, as shown in Table 1, if necessary, this kneading was performed by further adding a saccharide curing agent and a phenol resin. After disintegrating, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to obtain binder-coated refractories (1) to (10) coated with a coating layer made of sugar. . In the binder-coated refractories (1) to (10), the mass ratio of the coating layer was 2.5% by mass.

  Here, as shown in Table 1, as sugars, dextrin (“NDP-4C” “NDP-13” manufactured by Lignite Co., Ltd.), enzyme-modified dextrin (“NDP-3” “NDP-6” manufactured by Lignite Co., Ltd.) ), Sucrose (containing 98.2% by mass of sucrose and 0.7% by mass of reducing sugar). When dextrins are arranged in descending order of molecular weight, the order is “NDP-4C” and “NDP-13”. When enzyme-modified dextrins are arranged in descending order of molecular weight, the order is “NDP-6” and “NDP-4C”. is there. In addition, citric acid was used as a curing agent and dissolved in water. Moreover, as a phenol resin, a novolak-type phenol resin (“# 4800” manufactured by Lignite Co., Ltd .; softening point 91 ° C.), a resol-type phenol resin (“LT-9” manufactured by Lignite Co., Ltd.); softening point 90 ° C., gelation time 120 seconds (at 150 ° C.)) was used.

(Examples 1 to 10)
A mold was manufactured using the binder-coated refractories (1) to (10) prepared as described above. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is preheated to 120 ° C., and a binder-coated refractory is blown into the mold at a gauge pressure of 0.1 MPa and filled. did. Next, an air supply pipe is connected to the mold, and saturated steam having a gauge pressure of 0.4 MPa and a temperature of 143 ° C. generated by a boiler is heated with a superheated steam generator (“GE-100” manufactured by Nomura Engineering Co., Ltd.). Superheated steam obtained by heating at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h and blown into the mold for 20 seconds.

  In this way, a molded product having a size of 20 mm × 10 mm × 80 mm was molded in the mold, and the molded product was removed from the mold and taken out. At this time, when the mold was opened, the odor was measured by sniffing with the nose, and the bending strength of the molded article immediately after taking out from the mold was measured according to JIS K6910. The results are shown in Table 2.

  As can be seen in Table 2, Examples 1 to 7 and 10 using binder-coated refractories containing only saccharides as a binder have almost no odor and are also used in combination with a phenol resin. Also in Examples 8 and 9, since the content of the phenol resin was small, the odor was weak. As for the bending strength of the molded product, Examples 1 to 6 using a binder-coated refractory containing only saccharides as a binder show a low value, and the practice was to combine citric acid as a curing agent. In Examples 7 and 10 and Example 8.9 in which a phenol resin was used in combination, it was slightly high.

  Next, the molded product taken out from the mold as described above is placed in a hot-air circulating dryer whose internal temperature is set to 80 ° C., 120 ° C., 180 ° C., 220 ° C., 250 ° C. in advance, and heated for 60 minutes. Processed (aftercuring). The bending strength of the mold obtained by the heat treatment was measured according to JIS K 6910. The results are shown in Table 3.

  By bending the molded product taken out from the mold by heat treatment, the bending strength has been greatly increased from the values in Table 2 to the values in Table 3, confirming that the strength is greatly improved. The In addition, when the heating temperature is 80 ° C., the effect of improving the strength is not sufficiently observed. Therefore, it is confirmed that the heating temperature is preferably 100 ° C. or higher, and more preferably 150 ° C. or higher. Is done. Further, since the bending strength is lowered at the heating temperature of 250 ° C., it can be said that it is preferable to set the heating temperature at 240 ° C. or lower.

  Further, when the molded product taken out from the mold as described above was heat-treated with a 220 ° C. hot air circulation dryer, the heating time was set to 5 minutes, 15 minutes, 30 minutes, and 90 minutes. The bending strength of the mold obtained by heat treatment in this way was measured according to JIS K 6910. The results are shown in Table 4.

  As can be seen from the results of Table 4, when the heat treatment time is 5 minutes, the effect of improving the strength is not sufficiently observed. Therefore, the heat treatment time is preferably 10 minutes or more, and preferably 30 minutes or more. It is confirmed that the heating time is more preferable. Further, when the heating time is 90 minutes, it is lower than the bending strength of 220 ° C. × 60 minutes in Table 3, and it can be said that the heating time is preferably set shorter than 80 minutes.

  Next, in Examples 2, 3, 9, and 10, 2.5 g samples were cut out from the molded product before heat treatment and the mold after heat treatment at 180 ° C., 220 ° C., and 250 ° C., respectively. The amount of gas generated was measured for this sample. The measurement was performed by reading the gas amount every 10 seconds under a 700 ° C. atmosphere condition using a “casting sand gas generation amount tester (model: manual reading type)” manufactured by Hashimoto Rika Co., Ltd. The results every 30 seconds are shown in Table 5.

  As seen in Table 5, it is confirmed that the amount of gas generated can be further reduced by heat treatment, and the amount of gas generated during casting can be reduced.

(Example 11, Example 12)
Binder-coated refractory (3) or binder-coated refractory using a mold that molds a mold as a core of shape and mass with a diameter of 109 mm, height of 74 mm, and weight of about 735 g. (10) was filled by blowing with an air pressure of a gauge pressure of 0.1 MPa. Next, an air supply pipe is connected to the mold, and saturated steam having a gauge pressure of 0.4 MPa and a temperature of 143 ° C. generated by a boiler is heated with a superheated steam generator (“GE-100” manufactured by Nomura Engineering Co., Ltd.). Heated superheated steam at 350 ° C. and gauge pressure of 0.45 MPa was supplied at a flow rate of 100 kg / h and blown into the mold for 60 seconds.

  In this way, the molded product was molded in the mold, and the molded product was removed from the mold and taken out. Then, this molded product was put into a hot air circulation drier set at 250 ° C. and subjected to heat treatment (aftercuring) for 30 minutes to obtain a mold as a core.

  The mold obtained by the heat treatment as described above was set as a core in a green mold, and a test was performed in which a cast iron melt equivalent to FC200 having a casting temperature of 1250 to 1300 ° C. was cast. For comparison, a test was performed in which a cast iron melt was similarly cast using the molded product before heat treatment as a core. Then, the state of generation of odor and smoke at the time of casting was observed, the state of seizure to the core was observed, and the disintegration property of the core when the cast was taken out was observed. The results are shown in Table 6.

  As seen in Table 6, when the molded product before heat treatment is used as a mold, seizure occurs and there is a problem with heat resistance, but when this is heat treated and used as a mold, there is no occurrence of seizure, It is confirmed that the heat resistance can be improved. Further, although the heat resistance is improved as described above, the mold disintegration is good and there is no problem.

(Heat resistance test of sugars)
An enzyme-modified dextrin “NDP-3” was used as a saccharide, and a test for measuring heat resistance was performed. Samples to be tested are “NDP-3” which has not been heat-treated, “NDP-3” which has been heat-treated for 60 minutes in a dryer at 250 ° C., 225 g of “NDP-3” and 25 g of citric acid with water added. Mix well, put in a petri dish, dry at a temperature of 105 ° C, and then heat-treat in a 250 ° C dryer for 60 minutes.

  Each sample was subjected to thermal analysis at a rate of temperature increase of 10 ° C./min under a nitrogen atmosphere using a differential thermal / thermogravimetric simultaneous measurement device “DTG-60H” manufactured by Shimadzu Corporation, as shown in FIG. A graph of temperature-residual mass was obtained. From this graph, the remaining mass at 400 ° C. and 600 ° C. was determined and shown in Table 7.

  As can be seen in the graph of FIG. 3 and Table 7, the heat treatment of “NDP-3” increases the residual mass, that is, the decrease in mass due to heating is small. The heat resistance of “NDP-3” is improved. In particular, by adding citric acid to “NDP-3”, the mass loss is further reduced. This suggests that the sugars are polymerized and the molecular weight is increased by heat treatment, and the strength of the mold is improved as shown in Tables 3 and 4, and as shown in Table 6. It is considered that the heat resistance of the mold is improved because the saccharide is polymerized by the heat treatment, and the strength and heat resistance of the saccharide itself are increased.

DESCRIPTION OF SYMBOLS 1 Binder coated refractory 2 Mold 3 Mold 4 Heat-treatment container

Claims (16)

  Fill the mold with a binder-coated refractory formed by coating the surface of the refractory aggregate with a solid coating layer containing saccharides as a binder, and blow the steam into the mold to form a binder. By heating the coated refractory, the binder of the coating layer is solidified or cured, thereby forming a molded product in which the refractory aggregate is bonded with the binder, and molding the molded product into the mold. A method for producing a mold, wherein the molded product is heat-treated after being taken out from the mold.   The method for producing a mold according to claim 1, wherein the heat treatment of the molded product is performed at a temperature of 100 to 350 ° C.   The method for producing a mold according to claim 1 or 2, wherein the molded product is heat-treated for 10 to 200 minutes.   The method for producing a mold according to any one of claims 1 to 3, wherein the molded product taken out from the mold is heat-treated in a heat treatment container.   Water vapor is blown into a mold filled with a binder-coated refractory, and the condensed water of the water vapor is supplied into the mold to impart adhesiveness to the saccharide of the binder, and then blown into the mold. The method for producing a mold according to any one of claims 1 to 4, wherein the binder is solidified or cured by heating the binder-coated refractory with condensation latent heat and sensible heat of water vapor.   6. The mold according to claim 5, wherein heating of the binder-coated refractory in the mold is performed by water vapor blown into the mold and heated gas blown into the mold subsequently to the water vapor. Manufacturing method.   The method for producing a mold according to claim 6, wherein the heated gas is heated air.   The method for producing a mold according to claim 6, wherein the heated gas is a mixed gas of water vapor and air.   The method for producing a mold according to any one of claims 1 to 8, wherein the steam is superheated steam.   The method for producing a mold according to any one of claims 1 to 9, wherein the coating layer of the binder-coated refractory contains a carboxylic acid.   The method for producing a mold according to any one of claims 1 to 10, wherein the coating layer of the binder-coated refractory contains a thermosetting resin in addition to sugar as a binder.   The method for producing a mold according to claim 11, wherein a phenol resin is used as the thermosetting resin.   The method for producing a mold according to claim 11 or 12, wherein the content of the thermosetting resin in the binder is 80% by mass or less.   The method for producing a mold according to any one of claims 1 to 13, wherein the saccharide is selected from monosaccharides, small saccharides, and polysaccharides.   Filling the mold with the binder-coated refractory, supplying water into the mold to give the binder saccharide tackiness, and then blowing superheated steam into the mold, The method for producing a mold according to any one of claims 1 to 4, wherein the binder is solidified or cured by heating the binder-coated refractory material with latent heat of condensation and sensible heat.   Binder-coated refractory is filled into the mold, saturated steam is blown into the mold, and water vapor condensate is supplied to the binder to give the saccharide tackiness, and then into the mold. 5. The binder is solidified or cured by blowing superheated steam and heating the binder-coated refractory with the condensation latent heat and sensible heat of the superheated steam. Mold manufacturing method.

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