JP2012115870A - Method of manufacturing mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a mold capable of rigidly forming a surface layer part of a mold with no flaking away.SOLUTION: The surface of a fire-resistance aggregate of a binder coated refractory 2 is covered with a solid coating layer containing a binder which is selected from among saccharide, water-soluble enorganic compound, and water-soluble thermoplastic resin. The steam is blown into a mold 1 which is filled with the binder coated refractory 2, so that the binder coated refractory 2 is heated with the condensation latent heat of the steam, and the binder of the coating layer of the binder coated refractory 2 is moistened by the condensed water of the steam, for providing tackiness. After that, the binder is dried and solidified, so that the fire-resistance aggregate is bound with the binder, thus a mold is manufactured. In this case, the steam is blown into the mold 1 whose temperature is set to be 130°C or less.

Description

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

  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 cinnabar 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. Prepare a coated binder refractory (generally called resin-coated sand), fill this binder-coated refractory into a heated mold, and melt and cure the thermosetting resin binder. Therefore, the mold is made.

  In such a binder-coated refractory, as the thermosetting resin binder for coating the surface of the refractory aggregate, a phenol resin is generally used as described above, and among the phenol resins, a novolac type phenol resin is used. Is often used. Since this novolak-type phenol resin does not cure even when heated, it is common to use hexamethylenetetramine as a curing agent. When a binder-coated refractory prepared using a novolac type phenolic resin as a binder is filled in a mold heated to 250 to 350 ° C., it is heated by heat transfer from the mold and hexamethylenetetramine is converted into formaldehyde and ammonia. Most of the formaldehyde reacts with the novolac type phenolic resin to cure the phenolic resin in an infusible state.

  However, formaldehyde that has not contributed to the reaction and most of the ammonia will be volatilized into the atmosphere, and this formaldehyde and ammonia will not only affect the health of workers but also contaminate the environment. It was generated. When resol type phenol resin is used as the phenol resin, such a problem can be somewhat reduced. However, since unreacted formaldehyde is also released in the resole type phenol resin, the problem caused by harmful gases can be solved. It is not possible.

  On the other hand, the present applicant has proposed a method for producing a mold using water vapor in Patent Document 1 and the like. That is, a binder-coated refractory coated with a thermosetting resin binder such as a phenol resin is filled in a mold, and steam is blown into the mold, so that the binder-coated refractory is condensed with the latent heat of condensation of water vapor. Is heated instantaneously, and the mold can be produced by curing the thermosetting resin binder in a short time.

  If the mold is manufactured by the method of heating using water vapor in this way, even if harmful gas such as formaldehyde is released, it can be washed away by absorbing the harmful gas into the water vapor, which deteriorates the working environment. Can be reduced.

  And when the present applicant manufactures a mold by heating the binder-coated refractory with water vapor as described above, the present invention uses a binder-coated refractory prepared using saccharides as a binder. Patent application was filed as Japanese Patent Application No. 2009-209123.

  That is, when a mold is filled with a binder-coated refractory coated with saccharides as a binder and steam is blown into the mold, the binder-coated refractory is heated by the latent heat of condensation of the steam, The saccharides on the surface of the binder-coated refractory are wetted with the condensed water of the adhesive, and become sticky with adhesive properties, and the binder-coated refractories that are in contact with each other are adhered to each other with this paste-like saccharide. Can do. By heating with water vapor, moisture is evaporated from the saccharide, and the saccharide is dried and solidified, whereby a mold in which the refractory aggregate is bonded with a binder made of saccharide can be produced.

  In the present invention, even if the saccharide is decomposed by heating, it does not release a large amount of harmful gas. Therefore, the saccharide has the effect of not polluting the environment, and the saccharide has a decomposition temperature. Therefore, when the molten metal is poured into the mold, it is easily decomposed by heat and has an effect that a mold having good disintegration can be obtained.

Japanese Patent No. 3563973

  As described above, a binder coated refractory coated with saccharides as a binder is filled into a mold, and steam is blown into the mold to produce a mold. When observing the refractory aggregate, the refractory aggregate is firmly bonded to the inside of the mold that is not in contact with the surface of the mold that is filled with the binder-coated refractory and the mold is molded. Then, there may be a phenomenon in which a part where the bonding strength of the refractory aggregate is weak occurs. When the surface of the mold with a weak bonding force is rubbed, the refractory aggregate peels off and becomes tedious.

  Thus, when the reason for the occurrence of the burr phenomenon in the surface layer portion of the mold in contact with the surface of the mold was examined, it is considered that the mold for molding the mold is due to being heated to a high temperature as described above. That is, of the water vapor blown into the mold, the water vapor passing through the inside away from the mold surface is lowered in temperature by the binder-coated refractory, and condensed water is generated from the water vapor. The saccharide of the binder coated refractory can be moistened to form a sticky paste. On the other hand, when the mold is at such a high temperature, the water vapor passing near the surface of the mold does not drop much due to the heat of the mold, and much water vapor is discharged from the mold without condensing. Thus, in the vicinity of the surface of the hot mold, it is difficult for condensed water to be generated from water vapor, and even if condensed water is generated, it will evaporate immediately. The binder coated refractory is not supplied with sufficient moisture so that the saccharide becomes paste-like, and the saccharide is dried and solidified without causing sufficient adhesion to the saccharide. It is thought that the phenomenon of battering occurs due to shortage.

  When the burr phenomenon occurs in the surface layer portion of the mold as described above, the surface becomes rough, and the surface of the mold cannot be formed smoothly. For this reason, when performing casting using this mold, the surface of the casting becomes rough, which makes it difficult to perform precise casting.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide a method for manufacturing a mold that can firmly form a surface layer portion of the mold without a burr phenomenon.

  The method for producing a mold according to the present invention comprises a binder coated with a solid coating layer containing a binder selected from saccharides, water-soluble inorganic compounds and water-soluble thermoplastic resins on the surface of a refractory aggregate. Using a refractory, steam is blown into a mold filled with the binder-coated refractory, and the binder-coated refractory is heated with the latent heat of condensation of the steam and the binder-coated refractory is condensed with steam condensate. After the above-mentioned binder of the coating layer is moistened to give adhesiveness, the binder is dried and solidified to bond the refractory aggregate with the binder to produce a mold. Water vapor is blown into a mold whose temperature is set to 130 ° C. or lower.

  In manufacturing a mold by blowing water vapor into a mold filled with a binder coated refractory coated with a coating layer containing a sugar, a water-soluble inorganic compound, and a water-soluble thermoplastic resin as a binder, It swells or dissolves in condensed water, and water-soluble inorganic compounds and water-soluble thermoplastic resins dissolve in water vapor condensate to form a sticky paste that binds refractory aggregates with these binders. The mold can be manufactured, and at this time, by setting the mold temperature to 130 ° C. or less as described above, the influence of the heat of the mold can be reduced, and the water vapor blown into the mold can be reduced. Among them, it is difficult for condensed water to be generated from water vapor passing near the surface of the mold, and the binder coated refractory binder is also paste-like in the part in contact with the mold surface. Water to be It is possible to sufficiently supply the refractory aggregate on the surface layer part of the mold with the adhesive of this binder, and without causing the batter phenomenon on the surface layer part of the mold with high strength. A mold can be produced. In addition, saccharides are easily thermally decomposed at a relatively low temperature, and water-soluble inorganic compounds and water-soluble thermoplastic resins are easily dissolved in water, so that a mold having good disintegration can be produced. .

  The present invention also provides a coating of a binder-coated refractory by condensing water vapor and blowing the steam into a mold filled with the binder-coated refractory to heat the binder-coated refractory with the latent heat of condensation of water vapor. The binder of the layer is moistened to give adhesiveness, and the binder-coated refractory is heated with water vapor that is subsequently blown into the mold to dry and solidify the binder.

  When steam is blown into the mold, the condensed water generated when the steam contacts the binder coated refractory and is deprived of heat is supplied to the binder, and the solid binder is moistened by this condensed water. It is possible to bond the refractory aggregate with this adhesive force of the binder, and then the binder-coated refractory is heated by the condensation latent heat of water vapor to rapidly evaporate the water, The binder can be dried and solidified, and the mold can be produced in a short time only by the step of blowing water vapor into the mold.

  The present invention also provides a coating of a binder-coated refractory by condensing water vapor and blowing the steam into a mold filled with the binder-coated refractory to heat the binder-coated refractory with the latent heat of condensation of water vapor. The binder of the layer is moistened to give adhesiveness, and then the binder is dried and solidified by blowing a dry gas having a moisture content smaller than water vapor into the mold.

  After steam was blown into the mold, the binder was made sticky with the condensed water of steam as described above, and the refractory aggregate was combined, and then heated with steam by blowing dry gas into the mold. Water can be efficiently evaporated by the heat of the binder-coated refractory, and the binder can be dried and solidified, and a mold can be produced in a short time.

  Further, the present invention is characterized in that the dry gas is air, and the binder can be efficiently dried and solidified by using air as it is.

  The present invention also provides a coating of a binder-coated refractory by condensing water vapor and blowing the steam into a mold filled with the binder-coated refractory to heat the binder-coated refractory with the latent heat of condensation of water vapor. Moisten the binder of the layer to give stickiness, then blow the heated gas into the mold and evaporate the condensed water in the mold to dry the binder coated refractory binder It is characterized by solidifying.

  Efficient moisture is obtained by blowing steam into the mold, sticking the binder to the binder with the condensed water of steam as described above, and bonding the refractory aggregate, and then blowing heated dry gas into the mold. It can be evaporated well to dry and solidify the binder, and the mold can be produced in a short time.

  The present invention is characterized in that the heated gas is heated air, and the air can be used as it is to dry and solidify the binder efficiently.

  Further, the present invention is characterized in that the heated gas is a mixed gas of water vapor and air, and the drying and solidification of the binder is efficiently performed using the water vapor and air used in the production of the mold as they are. It can be done well.

  Further, the present invention is characterized in that a preheated binder-coated refractory is filled in a mold.

  By preheating the binder-coated refractory in this way, it is possible to reduce the temperature difference of the binder-coated refractory that accompanies seasonal temperature differences such as summer and winter, and the quality of the mold is stable. It can be manufactured.

  The present invention also uses a binder-coated refractory coated with a solid coating layer containing a thermosetting resin as a binder in addition to sugars, water-soluble inorganic compounds, and water-soluble thermoplastic resins. The thermosetting resin is heated and cured by the latent heat of condensation of water vapor blown into a mold filled with a binder-coated refractory.

  By using a thermosetting resin as a binder in this way, the heat resistance and low strength due to the use of sugars, water-soluble inorganic compounds, and water-soluble thermoplastic resins as a binder can be reduced with a thermosetting resin. A mold that can be supplemented and has excellent heat resistance and strength can be produced.

  According to the present invention, a mold is manufactured by blowing water vapor into a mold filled with a binder-coated refractory coated with a coating layer containing a saccharide, a water-soluble inorganic compound, and a water-soluble thermoplastic resin as a binder. Since the mold temperature is set to 130 ° C. or lower, the influence of the mold heat can be reduced, and the water vapor blown into the mold is condensed from the water vapor passing near the mold surface. Water is not likely to be generated, and water can be sufficiently supplied so that the binder of the binder-coated refractory is paste-like even at the part in contact with the mold surface. The refractory aggregate on the surface layer of the mold can be firmly bonded with the adhesiveness of the binder, and the surface layer of the mold is firmly formed without causing the batter phenomenon on the surface of the mold. Making a strong mold It is those that can be.

An example of the manufacturing method of the casting_mold | template which concerns on this invention is shown, (a) (b) is sectional drawing in each process, respectively.

  Embodiments of the present invention will be described below.

  In the present invention, the refractory aggregate is not particularly limited, and examples thereof include dredged sand, mountain sand, alumina sand, olivine sand, chromite sand, zircon sand, mullite sand, and other artificial sand. These may be used alone or in combination of a plurality of types.

  The binder-coated refractory according to the present invention is formed by coating the surface of the particles of the refractory aggregate with a coating layer containing a binder. And in this invention, the binder coated refractory which formed the coating layer using the binder chosen from saccharides, a water-soluble inorganic compound, and a water-soluble thermoplastic resin is used. Saccharides swell or dissolve in water and become sticky to become sticky, and water-soluble inorganic compounds and water-soluble thermoplastic resins dissolve in water and become sticky and show sticky These binders are water-adhesive binders that generate adhesiveness when moistened with water.

  Here, as the saccharide in the present invention, monosaccharides, oligosaccharides and polysaccharides can be used, and in addition to selecting one type from various monosaccharides, oligosaccharides and polysaccharides, Multiple types can be selected and used together.

  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, as polysaccharides, there are starch sugar, dextrin, xanthan gum, curdlan, pullulan, cycloamylose, chitin, chitosan, cellulose, starch, etc., one of these is selected or used in combination of two or more. be able to. Examples of starch include raw 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 succinate starch, Acid starch, higher fatty acid esterified starch, etc.), cross-linked starch, kraft starch, and wet heat-treated starch. Among these, low-viscosity starches such as roasted dextrin, cyclodextrin, enzyme-modified dextrin, acid-treated starch, oxidized starch, and crosslinked starch are preferred. Furthermore, saccharide-containing plants such as wheat, rice, potato, corn, tapioca, sweet potato, sago, amaranth and the like can be used. In addition, sugars that are commercially available for food use, such as white crude, medium crude, granulated sugar, invert sugar, super white sugar, medium white sugar, tri-warm sugar, and the like can be used. Furthermore, phenol-modified saccharides obtained by reacting saccharides with phenols can also be used.

  The coating layer may contain carboxylic acid as a curing agent for saccharides, particularly polysaccharides. The carboxylic acid is not particularly limited, and examples thereof include polyvalent carboxylic acids such as oxalic acid, maleic acid, succinic acid, citric acid, butanetetradicarboxylic acid, and methyl vinyl ether-maleic anhydride copolymer. it can. The content of the carboxylic acid in the coating layer is preferably in a range where the blending amount of the carboxylic acid with respect to the saccharide is 0.1 to 10 parts by mass of the carboxylic acid with respect to 100 parts by mass of the saccharide. Carboxylic acid is preferably mixed with saccharide in a state of being dissolved in water in advance because the effect as a curing agent is exhibited highly.

  In the present invention, the water-soluble inorganic compound is not particularly limited, but water glass, sodium chloride, sodium phosphate, sodium carbonate, sodium vanadate, sodium borate, sodium aluminum oxide, potassium chloride, potassium carbonate A sulfuric acid compound can be used. These can be used alone or in combination of any plural types.

Additional water glass is a mixture of silicic anhydride (SiO ₂₎ and sodium oxide _(Na 2 O), also called sodium silicate, represented by the general formula _{Na 2 O · nSiO 2 · xH} 2 O shown in JIS K1408, A powdery, liquid or crystalline material can be used. Further, potassium silicate (K ₂ O · nSiO ₂ ) can also be used.

Water glass is extremely soluble in water and solidifies by drying. For this reason, by using water glass as a binder, it is possible to produce a mold that easily disintegrates with water. Moreover, since water glass can be obtained at low cost, a mold can be manufactured at low cost. Furthermore, since Na ₂ SiO ₃ has a relatively high melting point of 1088 ° C., a mold having high heat resistance can be produced.

  The above-mentioned sodium chloride (NaCl) is edible, so-called salt, is harmless to the human body, is inexpensive, and is easy to use. And since it melt | dissolves easily in water, the casting_mold | template which disintegrates easily with water can be manufactured by using sodium chloride as a binder. In particular, the solubility of sodium chloride in water in the temperature range of 0 to 100 ° C. is 35.7 to 39.1 g with respect to 100 g of water, and the change due to the water temperature is small, so that workability is good. Further, since NaCl has a relatively high melting point of 1413 ° C., a mold having high heat resistance can be manufactured.

Examples of the sodium phosphate include monosodium phosphate hydrate (NaH ₂ PO ₄ xH ₂ O), disodium phosphate hydrate (Na ₂ HPO ₄ xH ₂ O), and trisodium phosphate hydrate. (Na ₃ PO ₄ .xH ₂ O) or the like can be used. Trisodium phosphate hydrate is soluble in water so that the amount dissolved in 100 g of water is 1.5 g (0 ° C.), and disodium phosphate hydrate has a melting point of 1340. As at ° C, the melting point of sodium phosphate is relatively high. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The above-mentioned sodium carbonate (K ₂ CO ₃ ) is easily dissolved in water and is inexpensive so that the amount dissolved in 100 g of water is 7.1 g (0 ° C.). The melting point is relatively high at 851 ° C. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The above sodium vanadate (Na ₃ VO ₄ ) is soluble in water and has a relatively high melting point of 866 ° C. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The sodium borate (Na ₂ B ₄ O ₇ xH ₂ O) is easily dissolved in water and inexpensive, so that the amount dissolved in 100 g of water is 1.6 g (10 ° C.). The melting point is relatively high at 741 ° C. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The sodium aluminum oxide (NaAlO ₂ ) is soluble in water and has a high melting point of 1700 ° C. or higher. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

  The potassium chloride (KCl) is easily dissolved in water and is inexpensive so that the amount dissolved in 100 g of water is 28.1 g (0 ° C.). The melting point is relatively high at 776 ° C. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The potassium carbonate (K ₂ CO ₃ ) is easily dissolved in water such that the amount dissolved in 100 g of water is 129.4 g (0 ° C.), and has a relatively high melting point of 891 ° C. For this reason, a mold that easily disintegrates with water and has high heat resistance can be produced.

The sulfuric acid compound is not particularly limited, but includes MgSO ₄ , Na ₂ SO ₄ .xH ₂ O, Al ₂ (SO ₄ ) ₃ .xH ₂ O, K ₂ SO ₄ , NiSO _4. xH ₂ O, ZnSO ₄ .xH ₂ O, MnSO ₄ .xH ₂ O, K ₂ Mg (SO ₄ ) ₂ .xH ₂ O, and the like can be given.

Sulfuric acid compounds are easily dissolved in water and inexpensive. For example, the amount dissolved in 100 g of water is 26.9 g (0 ° C.) for magnesium sulfate (MgSO ₄ ), 19.4 g (20 ° C.) for sodium sulfate decahydrate (Na ₂ SO ₄ .10H ₂ O), Aluminum sulfate 12 hydrate (Al ₂ (SO ₄ ) ₃ · 12H ₂ O) is 36.2 g (20 ° C.), potassium sulfate (K ₂ SO ₄ ) is 10.3 g (0 ° C.), nickel sulfate · 7 Hydrate (NiSO ₄ · 7H ₂ O) is 39.7 g (20 ° C.), and manganese sulfate · pentahydrate (MnSO ₄ · 5H ₂ O) is 75.3 g (25 ° C.). For this reason, by using a sulfuric acid compound as a binder, a mold that easily disintegrates with water can be produced at low cost. The melting point of the sulfate compound is, for example, 1185 ° C. for magnesium sulfate (MgSO ₄ ), 884 ° C. for sodium sulfate decahydrate (Na ₂ SO ₄ .10H ₂ O), and aluminum sulfate dodecahydrate (Al ₂ ( SO ₄ ) ₃ · 12H ₂ O) is 770 ° C., potassium sulfate (K ₂ SO ₄ ) is 1067 ° C., nickel sulfate heptahydrate (NiSO ₄ · 7H ₂ O) is 840 ° C., zinc sulfate · 7 hydrate The product (ZnSO ₄ .7H ₂ O) is 740 ° C., manganese sulfate pentahydrate (MnSO ₄ .5H ₂ O) is 850 ° C., and potassium magnesium sulfate (K ₂ Mg (SO ₄ ) ₂ .6H ₂ O) is Since it is relatively high at 927 ° C., a mold having high heat resistance can be produced.

  As the water-soluble inorganic compound, any one of the above-listed compounds can be selected and used alone, or any plurality of these can be used in combination.

  Furthermore, the water-soluble thermoplastic resin in the present invention is not particularly limited, but polyacrylamide, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polyvinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl methyl ether, methyl cellulose, And methoxylated nylon. Any one of these water-soluble thermoplastic resins can be selected and used alone, or a plurality of water-soluble thermoplastic resins can be used in combination.

  Each of the saccharide, the water-soluble inorganic compound, and the water-soluble thermoplastic resin may be used alone or in any combination. For example, saccharides and water-soluble inorganic compounds, saccharides and water-soluble thermoplastic resins, water-soluble inorganic compounds and water-soluble thermoplastic resins, and combinations of saccharides, water-soluble inorganic compounds and water-soluble thermoplastic resins can be used in combination. Thus, when using 2 or more types together, the combination ratio of combined use can be set arbitrarily.

  In the present invention, the coating layer contains a thermosetting resin as a binder in combination with a water-adhesive binder selected from the above saccharides, water-soluble inorganic compounds, and water-soluble thermoplastic resins. It may be. The thermosetting resin is not particularly limited as long as it is used as a binder for the mold, and a phenol resin, a furan resin, an isocyanate resin, or the like can be used. Of these, a phenol resin is most preferable, and the phenol resin may be either a resol type phenol resin or a novolac type phenol resin, or both may be used in combination.

  The amount of the thermosetting resin contained in the coating layer as the binder is not particularly limited, but is preferably set in the range of 10 to 90% by mass with respect to the total amount of the binder. The range of -70 mass% is more preferable. The thermosetting resin is contained in order to supplement the heat resistance and strength of the mold. However, a thermosetting resin such as a phenol resin may generate harmful gas when it is thermally decomposed. For this reason, it is preferable to set the content of the thermosetting resin in the above range so that the heat resistance and the strength can be supplemented while suppressing the generation of harmful gases.

  Furthermore, in order to improve the fluidity of the binder-coated refractory, a lubricant may be contained in the coating layer. 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 water-adhesive binder selected from saccharides, water-soluble inorganic compounds and water-soluble thermoplastic resins for the refractory aggregate particles, and optionally thermosetting resin binder, carboxylic acid, lubricant, etc. By blending and mixing, the coating layer containing the binder is coated on the surface of the refractory aggregate, and the binder-coated refractory according to the present invention can be obtained.

  The amount of the coating layer coated on the refractory aggregate differs depending on the components and applications, and cannot be specified unconditionally. However, the binder is 0.5 to 6.0 parts by mass with respect to 100 parts by mass of the refractory aggregate, and the lubricant. Is generally preferred to be in the range of 0.02 to 0.15 parts by mass in solid content. Examples of methods for 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. 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.) to obtain a granular free-flowing binder-coated refractory. In this respect, 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.

  Here, the water-adhesive binder is used in combination with the water-adhesive binder selected from saccharides, water-soluble inorganic compounds, and water-soluble thermoplastic resins as described above, and the thermosetting resin. A method for forming a coating layer containing a water-adhesive binder and a thermosetting resin binder by simultaneously coating a fire-resistant aggregate with a thermosetting resin binder, and the surface of the fire-resistant aggregate After coating with a water-adhesive binder, a two-layer coating layer of a water-adhesive binder and a thermosetting resin binder is formed by coating with a thermosetting resin binder. Method: After coating the surface of a fireproof aggregate with a thermosetting resin binder, a two-layer structure of a thermosetting resin binder and a water adhesive binder by coating with a water adhesive binder There is a method of forming a coating layer, and any method may be used.

  In manufacturing a mold using the binder-coated refractory prepared as described above, the binder-coated refractory is filled into the mold, and then steam is blown into the mold to condense the latent heat of condensation of the steam. Can be performed by heating the binder-coated refractory.

  That is, when steam is blown into a mold filled with a binder-coated refractory, first, the water vapor is deprived of heat by contacting the binder-coated refractory to produce condensed water, and the binder-coated refractory is produced. Condensed water acts on the binder of the coating layer. When condensed water acts on the solid state binder of the coating layer, when the binder is a saccharide, it absorbs this condensed water and swells or dissolves to gelatinize, and the binder is a water-soluble inorganic compound. Or a water-soluble thermoplastic resin, it is dissolved in this condensed water to become a liquid and gelatinized, and the binder made of saccharides, water-soluble inorganic compounds, and water-soluble thermoplastic resins is all paste-like. Stickiness occurs. Thus, when adhesiveness arises in the binder of a coated layer, the refractory aggregate of the binder coated refractory material filled in the type | mold is couple | bonded by the adhesiveness of this binder. Next, the binder-coated refractory is heated by the condensation latent heat of water vapor that is subsequently blown into the mold, and the moisture that acts on the binder evaporates and dries, and sugars, water-soluble inorganic compounds, water-soluble A binder made of a thermoplastic resin can be dried and solidified, and a refractory aggregate can be bonded with the solidified binder to form a mold.

  When the binder of the binder-coated refractory coating layer is heated with steam to produce a mold, the saccharide and water-soluble inorganic compound contained as the binder are heated and solidified. It does not generate a large amount of harmful gases, and even if gas is generated from a water-soluble thermoplastic resin contained as a binder, it is absorbed into water vapor and released to the atmosphere. That is, the mold can be manufactured without polluting the environment.

  And casting can be performed by pouring a high temperature molten metal into the mold produced as described above, and casting can be performed, but the binder saccharides that bind the refractory aggregate of the mold are relatively Because it decomposes at low temperatures, it is easily decomposed by the heat of the molten metal. In addition, since the water-soluble inorganic compound and water-soluble thermoplastic resin of the binder are easily dissolved in water, the binding force of the water-soluble inorganic compound and water-soluble thermoplastic resin is lost by immersing the mold in water. 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.

  Here, the saccharide is referred to as an inclusion compound, and has a property of wrapping a low molecular compound and gradually releasing it. And when saccharides and water-soluble inorganic compounds or water-soluble thermoplastic resins are used in combination as a binder, when steam is blown through a mold filled with a binder-coated refractory as described above, condensed water vapor There is a possibility that the water-soluble inorganic compound or the water-soluble thermoplastic resin dissolves in the water and flows along with the movement of the water vapor. That is, the water-soluble inorganic compound or water-soluble thermoplastic resin contained in the coating layer of the binder-coated refractory filled in the mold is moved from the upstream side to the downstream side by the flow of water vapor blown into the mold. The mold produced by moving and having more water-soluble inorganic compounds and water-soluble thermoplastic resins in the binder-coated refractory filled downstream than the binder-coated refractory filled upstream. In this case, water-soluble inorganic compounds and water-soluble thermoplastic resins are unevenly distributed, which may result in a heterogeneous mold. On the other hand, the presence of saccharides prevents water-soluble inorganic compounds and water-soluble thermoplastic resins from flowing together with water vapor by wrapping water-soluble inorganic compounds and water-soluble thermoplastic resins with inclusion compound saccharides. It can prevent the uneven distribution of water-soluble inorganic compounds and water-soluble thermoplastic resins, and can produce a homogeneous mold.

In addition, when steam is blown into the mold to solidify the binder of the binder-coated refractory filled in the mold, CO ₂ gas is not blown into the mold. For this reason, when water glass is used as the water-soluble inorganic compound, the water glass does not substantially react with CO ₂ and harden as in the case of producing a mold by the CO ₂ process. Therefore, even when water glass is used as the binder, the water glass is bonded to the binder-coated refractory in a solidified state rather than cured, and the uncured water glass is in water. Since it dissolves easily, the template can be easily disintegrated.

  On the other hand, when the coated layer of the binder coated refractory contains a thermosetting resin as a binder in addition to the water-adhesive binder of sugars, water-soluble inorganic compounds, and water-soluble thermoplastic resins When the water-adhesive binder of saccharides, water-soluble inorganic compound, and water-soluble thermoplastic resin is dried and solidified by blowing water vapor into the mold as described above and heating the binder-coated refractory, The thermosetting resin is melted and cured, and the refractory aggregate can be bonded also by the thermosetting resin binder, and a mold having high strength can be produced.

  In this way, when the binder-coated refractory is heated to cure the thermosetting resin, harmful gas may be generated from the thermosetting resin, but the thermosetting resin is a water-adhesive binder. Is used to supplement the heat resistance and strength of the mold when used alone, and does not need to be contained in a large amount in the coating layer. For this reason, the amount of harmful gas generated from the thermosetting resin is small, and environmental pollution can be suppressed.

  In addition, the combined use of a thermosetting resin as a binder increases the heat resistance and strength of the mold, so that the mold disintegration is reduced. However, the thermosetting resin is a saccharide, a water-soluble inorganic compound, a water-soluble heat Since it is used in combination with a plastic resin and the content of the thermosetting resin is not large as described above, the time for heating the mold is slightly increased, or the time for immersion in water is slightly increased. Therefore, the mold can be easily disintegrated, and the disintegration property of the mold is not particularly impaired.

  Next, an example of manufacturing a mold using water vapor will be described with reference to FIG. As shown in FIG. 1A, an injection port 4 is provided on the upper surface of a mold 1 formed by providing a cavity 3 therein, and a discharge port 6 closed by a net 5 such as a metal mesh is formed on the lower surface of the mold 1. It is provided. This type can be divided vertically or horizontally. The binder-coated refractory 2 is stored in a hopper 7, and an air supply pipe 9 with a cock 8 is connected to the hopper 7. Then, after the nozzle port 7a at the lower end of the hopper 7 is matched with the injection port 4 of the mold 1, the cock 8 is switched from closed to open, so that air is blown into the hopper 7 to pressurize it. The binder-coated refractory 2 is blown into the mold 1 to fill the cavity 3 of the mold 1 with the binder-coated refractory 2. Since the discharge port 6 is blocked by the net 5, the binder coated refractory 2 does not leak from the discharge port 6. When a plurality of the inlets 4 and the outlets 6 are provided in the mold 1 as in the embodiment of FIG. 1, the binder-coated refractory 2 can be inserted from one or a plurality of the inlets 4. Good.

  Here, since the coating layer of the binder-coated refractory 2 is made of a solid binder, the binder-coated refractory 2 has no adhesiveness on the surface and has good fluidity. . Accordingly, when the binder 1 is filled with the binder-coated refractory 2 as described above, the binder-coated refractory 2 can be smoothly poured into the cavity 3 of the mold 1, and the mold 1 has a good filling property. The binder coated refractory 2 can be filled, and the occurrence of poor filling can be prevented.

  After filling the mold 1 with the binder-coated refractory 2 as described above, the hopper 7 is removed from the inlet 4 of the mold 1 and an air supply pipe 10 is connected to each inlet 4 as shown in FIG. Connect. Water vapor and heated gas can be selectively supplied to the air supply pipe 10. The cock 11 of the air supply pipe 10 is opened, and water vapor is first blown into the cavity 3 of the mold 1.

  When steam is blown into the mold 1 in this way, in the initial step of blowing steam, the steam contacts the surface of the binder-coated refractory 2 so that the latent heat is converted from the steam into the binder-coated refractory 2. The water vapor is deprived and condensed, and condensed water is generated on the surface of the binder-coated refractory 2. Since the saccharide of the coating layer on the surface of the binder-coated refractory 2, the water-soluble inorganic compound, and the water-adhesive binder of the water-soluble thermoplastic resin are solid, the binder-coated refractory 2 is still solid. However, when condensed water is supplied to the surface of the binder-coated refractory 2 as described above, the solid water-adhesive binder is paste-like by the condensed water as described above. Thus, stickiness is generated, and the refractory aggregate can be bonded by the adhesiveness of the binder.

  At this time, water vapor blown into the cavity 3 in the mold 1 passes through the interior away from the surface of the mold 1 and is discharged from the discharge port 4, or passes near the surface of the mold 1 and discharge port 4. There is something that is discharged from. When the mold 1 is heated to a high temperature, the high temperature of the mold 1 does not act on the water vapor that passes through the inside away from the surface of the mold 1, so that the latent heat of the water vapor is condensed as described above. The temperature is lowered by the agent-coated refractory 2 and the water vapor is condensed to produce condensed water. The water-adhesive binder of the coated layer is moistened with the condensed water and becomes a paste having adhesiveness. However, since the high temperature of the mold 1 acts on the water vapor that passes through the vicinity of the surface of the mold 1, even if the water vapor contacts the binder coated refractory 2, this high temperature effect of the mold 1. Thus, the temperature of the water vapor does not decrease so much, and much of the water vapor is discharged from the mold 1 without condensing. Therefore, it is difficult for condensed water to be generated from water vapor passing in the vicinity of the surface of the hot mold 1, and even if condensed water is generated, it will evaporate immediately. Sufficient moisture is not supplied to the adhesive-coated refractory 2 in contact with the water-adhesive binder until the water-adhesive binder becomes paste-like, and the water-adhesive binder remains sufficiently adhesive. The water-adhesive binder will dry and solidify. As a result, the refractory aggregate of the binder coated refractory 2 in the part in contact with the surface of the mold 1 cannot be sufficiently bonded with the binder, and the refractory aggregate having insufficient bonding force is tattered from the mold surface. There is a possibility that a battering phenomenon occurs.

  Therefore, in the present invention, the temperature of the mold 1 is set to 130 ° C. or lower. When the temperature of the mold 1 is 130 ° C. or less, the high temperature of the mold 1 does not act on the water vapor that passes through the vicinity of the surface of the mold 1, and the water vapor is bonded to the binder-coated refractory 2. It can reduce that the temperature fall at the time of contacting with is suppressed, and condensed water is easily produced | generated from water vapor | steam also in the vicinity of the surface of the type | mold 1. FIG. For this reason, even in the binder coated refractory 2 in contact with the surface of the mold 1, water can be sufficiently supplied so that the water-adhesive binder becomes paste-like, and the surface of the mold 1 can be supplied. The refractory aggregate of the binder coated refractory 2 in contact with the binder can be sufficiently bonded with the binder, and the refractory aggregate is firmly bonded even in the surface layer of the mold to thereby strengthen the surface strength. Can be obtained, and the occurrence of a battering phenomenon on the surface of the mold can be prevented.

  The temperature of the mold 1 is required to be 130 ° C. or lower, more preferably 110 ° C. or lower, and still more preferably 90 ° C. or lower. Thus, as the temperature of the mold 1 becomes lower, the strength of the surface of the mold is improved, and the battering phenomenon can be further improved. However, if the temperature of the mold 1 is too low, the productivity of producing the mold by heating the binder-coated refractory 2 with the latent heat of condensation of the steam blown into the mold 1 may be reduced. Is set to 20 ° C. or higher, preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and still more preferably 50 ° C. or higher.

  Here, in the present invention, the temperature of the mold 1 refers to the surface temperature in the cavity 3 in which the binder-coated refractory 2 is filled to mold the mold, and immediately before water vapor is blown into the mold 1. The temperature at the time. Since the cavity 3 of the mold 1 is filled with the binder-coated refractory 2 before blowing water vapor, the temperature of the mold 1 may slightly change after the binder-coated refractory 2 is filled. Depending on the temperature of the binder-coated refractory 2, the temperature of the mold 1 is adjusted to be higher or lower so that the temperature after filling the binder-coated refractory 2 is in the above range. preferable.

  Water vapor is blown into the mold 1 filled with the binder-coated refractory 2 as described above, and the water-adhesive binder of the binder-coated refractory 2 is gelatinized. After the materials are adhesively bonded, the binder-coated refractory 2 is heated by the condensation latent heat of water vapor that is subsequently blown into the mold 1. Since water vapor has a high latent heat, the temperature of the binder-coated refractory 2 rapidly rises to around 100 ° C. due to this latent heat transferred when the water vapor condenses. Thus, the time during which the binder-coated refractory 2 is heated to near 100 ° C. by the heat transfer of the latent heat of the water vapor is the temperature of the water vapor, the flow rate into the mold 1, and the binder-coated refractory in the mold 1. Although it varies depending on the filling amount of the object 2, it is usually a short time of about 3 to 30 seconds. The water vapor blown into the mold 1 from the inlet 4 is exhausted from the outlet 6 after heating the binder-coated refractory 2 in the mold 1. At this time, moisture contained in the water-adhesive binder on the surface of the binder-coated refractory 2 can be evaporated and dried, and the water-adhesive binder can be solidified. It can be done. And the bond of the refractory aggregate due to the adhesive action of the water-adhesive binder becomes strong when the binder solidifies, and a high-strength mold can be obtained. When a thermosetting resin is contained as a pressure-sensitive adhesive in addition to saccharides, water-soluble inorganic compounds, and water-soluble thermoplastic resin water-adhesive binders, this rapid heating with water vapor allows the thermosetting resin to be A mold having higher strength can be obtained by melting and curing, and by a bonding action of a thermosetting resin.

  Alternatively, after the temperature of the binder-coated refractory 2 has risen to around 100 ° C., the supply to the air supply pipe 10 may be switched to the heated gas, and the heated gas may be blown into the mold 1. 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 10 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 2 is solidified or cured. The upper limit of the temperature of the heated gas is not particularly set as long as it is not higher than the temperature at which the binder is decomposed.

  When steam is blown into the mold 1 as described above, the temperature of the binder-coated refractory 2 can be rapidly increased to around 100 ° C. by the latent heat transferred when the steam condenses. In order to raise the temperature to not lower than ° C., it is necessary to evaporate the condensed water on the surface of the binder-coated refractory 2. 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 1 as described above, and since the heated gas is a dry gas having a lower moisture content and lower moisture content than the water vapor, it is generated in the mold 1. 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, by blowing heated gas into the mold 1, 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 2 can be raised to 100 ° C. or more in a short time after the heated gas starts to be blown into the mold 1, and the binder of the binder-coated refractory 2 can be increased. The speed at which the temperature in the mold 1 is increased to a temperature equal to or higher than the temperature at which the material solidifies or cures can be increased. As a result, it is possible to produce a mold with high strength in a short heating time.

  Further, when the condensed water is heated and evaporated as described above, the volume of the water vapor is reduced due to condensation, the pressure decreases, and the condensed water stays in the mold 1, and drying and temperature increase occur. Although the heating gas does not shrink in volume due to condensation and there is almost no pressure drop, the heating gas spreads into the mold 1 from the inlet 4 to the outlet 6 and is uniform throughout the mold 1. The temperature of the heated gas is allowed to act, so that drying and temperature increase are performed quickly.

  The time for blowing the heated gas into the mold 1 varies depending on the temperature of the heated gas, the flow rate of blowing into the mold 1, the filling amount of the binder-coated refractory 2 in the mold 1, the amount of condensed water in the mold 1, and the like. However, it is usually a short time of about 5 to 30 seconds. Therefore, it is possible to manufacture the mold in a short time of about 10 seconds to 1 minute after the start of blowing water vapor into the mold 1.

  Here, as the steam blown into the mold 1, saturated steam can be used as it is, but in the present invention, it is preferable to use superheated steam. 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.

  Further, as shown in FIGS. 1 (a) to 1 (b), when filling the cavity 3 of the mold 1 with the binder-coated refractory 2, the binder-coated refractory 2 is heated in advance, The heated binder-coated refractory 2 may be supplied to the mold 1 to fill the cavity 3. By preheating the binder-coated refractory 2 in this way, it is possible to obtain a high effect of shortening the molding time of the mold. In addition, if the temperature of the binder-coated refractory 2 fluctuates due to changes in the ambient temperature, such as in the summer or winter, the quality of the produced mold may vary, but the binder-coated refractory 2 is preheated. If the mold is used at a constant temperature, the mold can be manufactured with stable quality.

  The preliminary heating of the binder-coated refractory 2 can be performed, for example, in a hopper 7 that stores the binder-coated refractory 2. The temperature at which the binder-coated refractory 2 is preheated is not particularly limited, but is preferably in the range of about 30 to 100 ° C.

  When the thermosetting resin is not included as a binder in the coating layer of the binder-coated refractory 2, water vapor is blown into the mold 1 filled with the binder-coated refractory 2 as described above. After the water-adhesive binder of the binder-coated refractory 2 is gelatinized and the fire-resistant aggregate is bonded with the adhesive binder, the supply to the air supply pipe 10 is changed to dry gas. Switching may be performed so that dry gas is blown into the mold 1.

  The water-adhesive binder of saccharides, water-soluble inorganic compound, and water-soluble thermoplastic resin adheres the fire-resistant aggregate of the binder-coated refractory 2 with the adhesive strength when absorbing moisture as described above, Thereafter, the refractory aggregate can be firmly bonded by evaporating the moisture and drying and solidifying it. Therefore, after steam is blown into the mold 1 and condensed water is supplied to the water-adhesive binder and gelatinized, a dry gas is blown into the mold 1 without any heating, and dry air is used. By evaporating the water of the condensed water, the water-adhesive binder can be dried and the adhesive can be solidified.

The dry gas only needs to have a moisture content lower than that of water vapor. In particular, it is not necessary to dry the gas in order to reduce the moisture content, and air in the atmosphere can be used as it is. Further, it is not necessary to heat and use the air, and energy consumption can be minimized. The moisture content of the dry gas may be about 4.8 to 82.8 g / m ³ , and the temperature of the dry gas may be about 0 to 50 ° C. Of course, it is not limited to this range. The time for blowing the dry gas into the mold 1 is not particularly limited, and is appropriately set until the moisture contained in the mold in the mold 1 is dried.

  In addition, the water-adhesive binder of saccharides, water-soluble inorganic compound, and water-soluble thermoplastic resin may be dried so as to be solid in the mold 1 and can maintain the shape as a mold. The binder may be insufficiently dried and may contain some moisture. When moisture is contained in the binder, the mold is taken out from the mold 1 and then naturally dried or forcedly dried in an oven or the like.

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

(Preparation of binder coated refractories No. 1 and 2)
30 kg of flattered cinnabar sand heated to 130 ° 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. After disintegrating, 30 g of calcium stearate is added as a lubricant, kneaded for 15 seconds, and further aerated to obtain a binder-coated refractory No. 1 or 2 coated with a coating layer containing a saccharide as a binder. It was. The binder-coated refractories No. 1 and No. 2 were free-flowing granular materials, and the mass ratio of the coating layer was 2.0% by mass.

(Preparation of binder coated refractories No. 3 and 4)
30 kg of flattered cinnabar sand heated to 140 ° C. is put in a whirl mixer, and after adding the phenolic resin shown in Table 1 and mixing for 30 seconds, an aqueous solution in which the sugars shown in Table 1 are dissolved in 450 g of water is added and kneaded for about 90 seconds. did. After disintegrating, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated, whereby a binder coated refractory No. 3 coated with a coating layer containing saccharide and phenol resin as a binder. 4 was obtained. The binder-coated refractory Nos. 3 and 4 were smooth granular materials, and the mass ratio of the coating layer was 2.0% by mass.

  Here, as shown in Table 1, dextrin (“ND-S” manufactured by Nissho Kagaku Co., Ltd.) and enzyme-modified dextrin (“Amicol No6-H” manufactured by Nissho Kagaku Co., Ltd.) were used as sugars. 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.

(Preparation of binder coated refractory No. 5, 6)
30 kg of flattered cinnabar sand heated to 140 ° C. was placed in a whirl mixer, and an aqueous solution in which the water-soluble inorganic compound shown in Table 2 was dissolved or dispersed in 450 g of water was added and kneaded for about 90 seconds. After disintegrating, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated, whereby a binder-coated refractory No. 5, coated with a coating layer containing a water-soluble inorganic compound as a binder. 6 was obtained. The binder-coated refractory Nos. 5 and 6 were smooth granules, and the mass ratio of the coating layer was 4.0% by mass.

(Preparation of binder coated refractories No. 7 and 8)
30 kg of flattered cinnabar sand heated to 130 ° C. was put in a whirl mixer, and an aqueous solution in which sugars and water-soluble inorganic compounds shown in Table 2 were dissolved or dispersed in 450 g of water was added and kneaded for about 90 seconds. After disintegrating, 30 g of calcium stearate as a lubricant was added, kneaded for 15 seconds, and further aerated, whereby a binder-coated refractory coated with a coating layer containing a saccharide and a water-soluble inorganic compound as a binder. Nos. 7 and 8 were obtained. The binder-coated refractory Nos. 7 and 8 were smooth granular materials, and the mass ratio of the coating layer was 4.0% by mass.

(Preparation of binder coated refractories No. 9 and 10)
30 kg of flattered cinnabar sand heated to 140 ° C. was placed in a whirl mixer, and the phenol resin shown in Table 2 was added thereto and mixed for 30 seconds. Next, an aqueous solution in which the water-soluble inorganic compound shown in Table 2 was dissolved in 450 g of water was added, and kneaded until the sand grains collapsed. After disintegrating, 30 g of calcium stearate as a lubricant was added, kneaded for 15 seconds, and further aerated, whereby a binder coated refractory coated with a coating layer containing a phenol resin and a water-soluble inorganic compound as a binder. Product Nos. 9 and 10 were obtained. The binder-coated refractory Nos. 9 and 10 were smooth granular materials, and the mass ratio of the coating layer was 2.0% by mass.

Here, as shown in Table 2, as water-soluble inorganic compounds, water glass (sodium silicate No. 1 manufactured by Fuji Chemical Co., Ltd .; solid content 50 mass%), sodium sulfate (anhydrous boron nitrate (Na ₂ ) as a reagent of JIS K 8987) SO ₄ )) and dextrin (“No102S” manufactured by Nissho Kagaku Co., Ltd.) was used as the saccharide. Furthermore, 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 as the phenol resin.

(Preparation of binder coated refractory No11)
30 kg of flattered cinnabar sand heated to 130 ° C. was placed in a whirl mixer, and an aqueous solution in which water-soluble thermoplastic resin shown in Table 3 was dissolved or dispersed in 450 g of water was added and kneaded for about 90 seconds. After disintegrating, 30 g of calcium stearate as a lubricant was added, kneaded for 15 seconds, and further aerated, whereby a binder-coated refractory No11 coated with a coating layer containing a water-soluble thermoplastic resin as a binder. Got. This binder-coated refractory No11 was a smooth granular material, and the mass ratio of the coating layer was 2.0% by mass.

(Preparation of binder coated refractory No12)
30 kg of flattered silica sand heated to 130 ° C. was placed in a whirl mixer, and an aqueous solution in which water-soluble inorganic compounds and water-soluble thermoplastic resins shown in Table 3 were dissolved or dispersed in 450 g of water was added and kneaded for about 90 seconds. After disintegrating, 30 g of calcium stearate is added as a lubricant, kneaded for 15 seconds, and further aerated, so that the caking is coated with a coating layer containing a water-soluble inorganic compound and a water-soluble thermoplastic resin as a caking agent. Agent coated refractory No12 was obtained. This binder coated refractory No12 was a smooth granular material, and the mass ratio of the coating layer was 2.0 mass%.

(Preparation of binder coated refractory No13)
30 kg of flattered cinnabar sand heated to 130 ° C. was placed in a whirl mixer, and an aqueous solution in which sugars, water-soluble inorganic compounds, and water-soluble thermoplastic resins shown in Table 3 were dissolved or dispersed in 450 g of water was added thereto and kneaded for about 90 seconds. . After disintegration, 30 g of calcium stearate was added as a lubricant, kneaded for 15 seconds, and further aerated to coat with a coating layer containing saccharides, a water-soluble inorganic compound, and a water-soluble thermoplastic resin as a binder. Binder coated refractory No13 was obtained. This binder coated refractory No13 was a smooth granular material, and the mass ratio of the coating layer was 2.0 mass%.

(Preparation of binder coated refractory No. 14-16)
30 kg of flattered cinnabar sand heated to 140 ° C. is put into a whirl mixer, and after adding the phenolic resin shown in Table 3 and mixing for 30 seconds, saccharides, water-soluble inorganic compounds and water-soluble thermoplastic resins shown in Table 3 are further added. An aqueous solution dissolved in 450 g of water was added and kneaded for about 90 seconds. After disintegration, 30 g of calcium stearate is added as a lubricant, kneaded for 15 seconds, and further aerated to thereby form a coating layer containing a phenol resin and a saccharide, a water-soluble inorganic compound, and a water-soluble thermoplastic resin as a binder. Binder coated refractories No. 14-16 coated with The binder-coated refractories No. 14 to 16 were smooth granular materials, and the mass ratio of the coating layer was 2.0% by mass.

Here, as shown in Table 3, dextrin (“No102S” manufactured by Nissho Kagaku Co., Ltd.) is used as the saccharide, and water glass (sodium silicate No. 1 manufactured by Fuji Chemical Co., Ltd.); Mass%) was used. Polyvinyl alcohol (“PVA205” manufactured by Kuraray Co., Ltd.) was used as the water-soluble thermoplastic resin. Furthermore, 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 as the phenol resin.

  A mold was prepared using the binder-coated refractories No. 1 to 16 prepared as described above. A mold having a cavity size of 20 mm × 10 mm × 80 mm was preheated and heated to 50 ° C., 70 ° C., 90 ° C., 110 ° C., 130 ° C., and 150 ° C., respectively. First, the binder-coated refractories No1 to No16 adjusted to a temperature of 25 ° C. were blown into the mold with an air pressure of a gauge pressure of 0.1 MPa and filled. Next, an air supply pipe is connected to the mold, and saturated steam with 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 prepared at 350 ° C. and gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h and blown into the mold for 30 seconds.

  Thus, a 20 mm × 10 mm × 80 mm mold for bending test was formed, and the bending strength of this mold was measured in accordance with JIS K6910. The results are shown in Table 4.

  In addition, for the bending test mold formed as described above, the strength of the mold surface (dragging) is determined according to JIS K5600-5-4 “Paint General Test Method—Part 5: Mechanical Properties of Coating Film—Section 4 'Scratch hardness (pencil method)'. At this time, in order to see the difference in hardness, pencil hardness of 6B to 9H described in the old JIS K5400 was performed, and the results are shown in Table 4. In Table 4, “x” means that the surface roughness is so large that it cannot be tested. Here, if the pencil hardness on the surface of the mold is 3H or more, a casting having a good casting surface can be cast, and therefore it can be evaluated as acceptable.

  As can be seen from Table 4, when the mold temperature is 150 ° C, most of the pencil hardness is less than 3H and the surface of the mold is bagged, but the mold temperature should be set to 130 ° C or lower. As a result, it is confirmed that the pencil hardness of 3H or more is improved and the surface of the mold is improved. It is confirmed that when the mold temperature is 110 ° C., the surface of the mold is further improved, and when the mold temperature is 90 ° C. or less, there is no problem with the mold.

  Next, a mold having a cavity size of 150 mm long × 100 mm wide × 20 mm thick is preheated and heated to 50 ° C., 70 ° C., 90 ° C., 110 ° C., 130 ° C., and 150 ° C., respectively. It was. Then, the binder-coated refractories No1, No5, No7, No11, No12, and No13 adjusted to a temperature of 25 ° C. are blown into the mold in the same manner as described above, and then the same superheated steam as described above is filled into the mold. A mold was formed by blowing for a second.

  The mold was taken out of the mold and cooled to room temperature, and then the surface of the mold was touched with a finger to observe the battered state. The result is “○” when there is no sand grain peeling even if it is rubbed strongly with a finger. Table 5 shows that the sand particles peeled off when touched are evaluated as “x” because the sandiness is large.

  As can be seen from Table 5, when the mold temperature is 150 ° C., all are “x”, but by setting the mold temperature to 130 ° C. or less, many are “◯” or “Δ”. When the mold temperature was 110 ° C., the “x” disappeared, and when the mold temperature was 90 ° C. or less, the evaluation of “◯” was obtained.

  By combining the results of Table 4 and Table 5 above, by setting the mold temperature to 130 ° C. or less, it is possible to improve the battering phenomenon of the surface layer portion of the mold and form a strong mold. If the temperature is 110 ° C. or lower, this improvement effect is high. In particular, if the temperature of the mold is 90 ° C. or lower, it is confirmed that a mold having a high strength can be produced without any problem on the surface.

(Examples 1-3)
A mold having a cavity size of 20 mm × 10 mm × 80 mm was preheated and heated to 90 ° C. for use. First, binder-coated refractories No1, No3, No7 adjusted to a temperature of 25 ° C. were blown into the mold with an air pressure of a gauge pressure of 0.1 MPa and filled. Next, an air supply pipe is connected to the mold, and saturated steam with 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 prepared at 350 ° C. and gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h and blown into the mold for 20 seconds.

Next, blowing of superheated water vapor was stopped, switching to blowing of dry gas, and air at 25 ° C. with a saturated water vapor amount of 23.0 g / cm ³ was blown at a gauge pressure of 0.2 MPa for 20 seconds.

  In this way, a 20 mm × 10 mm × 80 mm mold for bending test was formed, the bending strength of this mold was measured in the same manner as described above, and the strength (blurring) of the mold surface was measured in the same manner as described above. It was measured by scratch hardness (pencil method). The results are shown in Table 6.

  As can be seen from Table 6, no battering phenomenon occurred in the surface layer portion of the mold, and a high-strength mold could be formed.

(Examples 4 to 6)
In the above Examples 1 to 3, instead of dry gas air, air heated to 300 ° C. was blown as a heated gas at a gauge pressure of 0.25 MPa for 20 seconds, and 20 mm × 10 mm × 80 mm for a bending test. The mold was made. Similarly, the bending strength and the surface strength (dragging) were measured, and the results are shown in Table 7.

  As can be seen from Table 7, no battering phenomenon occurred in the surface layer portion of the mold, and a high-strength mold could be formed.

1 type 2 binder coated refractory 3 cavity

Next, blowing of superheated water vapor was stopped, switching to blowing of dry gas, and air at 25 ° C. with a water vapor amount of 23.0 g / m ³ was blown in at a gauge pressure of 0.2 MPa for 20 seconds.

Claims (10)

  This binder coated refractory is coated with a solid coating layer containing a binder selected from saccharides, water-soluble inorganic compounds, and water-soluble thermoplastic resins on the surface of the refractory aggregate. Steam is blown into a mold filled with refractory, and the binder-coated refractory is heated with the latent heat of condensation of the steam, and the above-mentioned binder of the coating layer of the binder-coated refractory is moistened with the condensed water of steam. In the mold, the temperature of the mold is set to 130 ° C. or lower when the mold is manufactured by bonding the refractory aggregate with the binder by drying and solidifying the binder after giving the adhesive. A method for producing a mold, characterized in that water vapor is blown into the mold.   Steam is blown into a mold filled with a binder-coated refractory, and the binder-coated refractory is heated with the condensation latent heat of the steam, and at the same time, the binder of the coating layer of the binder-coated refractory with the condensed water of the steam. 2. The mold production according to claim 1, wherein the adhesive is wetted to give tackiness, and the binder-coated refractory is heated and dried to solidify the binder with steam successively blown into the mold. Method.   Steam is blown into a mold filled with a binder-coated refractory, and the binder-coated refractory is heated with the condensation latent heat of the steam, and at the same time, the binder of the coating layer of the binder-coated refractory with the condensed water of the steam. The method for producing a mold according to claim 1, characterized in that the mold is moisturized to give adhesiveness, and then the binder is dried and solidified by blowing dry gas having a moisture content smaller than water vapor into the mold.   The method for producing a mold according to claim 3, wherein the dry gas is air.   Steam is blown into a mold filled with a binder-coated refractory, and the binder-coated refractory is heated with the condensation latent heat of the steam, and at the same time, the binder of the coating layer of the binder-coated refractory with the condensed water of the steam. It is characterized in that the adhesive is moistened and then the heated gas is blown into the mold and the condensed water in the mold is evaporated to dry and solidify the binder of the binder coated refractory. The method for producing a mold according to claim 1.   The method for producing a mold according to claim 5, wherein the heated gas is heated air.   The method for producing a mold according to claim 5, 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 7, wherein the water vapor is superheated water vapor.   The method for producing a mold according to any one of claims 1 to 8, wherein a preheated binder-coated refractory is filled in a mold.   In addition to saccharides, water-soluble inorganic compounds and water-soluble thermoplastic resins, a binder-coated refractory coated with a solid coating layer containing a thermosetting resin as a binder is used. The method for producing a mold according to any one of claims 1 to 9, wherein the thermosetting resin is heated and cured with the latent heat of condensation of water vapor blown into a mold filled with.

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