JP5517246B2 - Mold manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a mold used for casting.

  Currently used molds are generally hard molds such as green sand mold, high pressure mold, high speed mold, etc., which use clay as a binder, thermosetting mold, self-hardening mold, gas curing mold, precision casting mold, etc. They are classified into special molds that use adhesive binders and other molds.

  These molds have their merits and demerits, but high temperature heating is necessary when producing the mold, and it takes time to cure the binder, and it is difficult to produce the mold stably in a short time. In many cases, toxic gas may be generated when the mold is produced.

  Therefore, the present applicant fills a mold with a coated sand prepared by mixing a binder with a refractory aggregate, blows steam into the mold, and heats the binder with steam to solidify or cure. A method for producing a mold is proposed.

  FIG. 5 shows an example of a method for producing a mold using water vapor (see Patent Documents 1 and 2, etc.). As shown in FIG. 5A, an injection port 11 is provided on the upper surface of the mold 1 formed by providing the cavity 10 therein, and an exhaust port 13 closed by a net 12 is provided on the lower surface of the mold 1. . The coated sand 2 is stored in a hopper 14, and an air supply pipe 16 with a cock 15 is connected to the hopper 14. Then, after the nozzle port 17 at the lower end of the hopper 14 is matched with the injection port 11 of the mold 1, the cock 15 is opened and air is blown into the hopper 14 to pressurize the hopper 14, and the coated sand 2 in the hopper 14 is pressed. 5 is blown into the mold 1 with this air pressure as shown in FIG. 5B, and the coated sand 2 is filled into the cavity 10 of the mold 1. Since the exhaust port 13 is blocked by the net 12, the coated sand 2 does not leak from the exhaust port 13.

  After filling the coated sand 2 into the mold 1 in this way, the hopper 14 is removed from the inlet 11 of the mold 1, and then a steam pipe 19 with a cock 18 is connected to the inlet 11 as shown in FIG. To do. Then, the cock 18 is opened and water vapor is blown into the cavity 10 of the mold 1 from the water vapor pipe 19. The water vapor passes between the particles of the coated sand 2 filled in the mold 1 to heat the coated sand 2 and is then discharged from the exhaust port 13. Since water vapor has high condensation latent heat, by blowing water vapor in this way, this latent heat is transmitted when the water vapor contacts the coated sand 2, and the entire coated sand 2 in the mold 1 can be instantaneously heated. The binder can be solidified or cured in a short time. Therefore, it is not necessary to heat the mold to a high temperature, the mold can be stably formed in a short time, and generation of toxic gas can be prevented.

Japanese Patent No. 3563973 Japanese Patent No. 4181251

  When the mold is manufactured by blowing water vapor into the mold 1 filled with the coated sand 2 as described above, the manufacturing process is performed as shown in FIGS. 5 (a) and 5 (b). From the step of connecting to the mold 1 and supplying and filling the coated sand 2 into the mold 1, and the step of connecting the water vapor pipe 19 to the mold 1 and blowing water vapor into the mold 1 as shown in FIG. Become.

  Here, in the steps of FIGS. 5A and 5B, the time required for supplying and filling the coated sand 2 into the mold 1 is about 10 to 30 seconds, and the step of FIG. Thus, the time required to solidify or cure the binder of the coated sand 2 by blowing steam into the mold 1 is about 10 to 60 seconds.

  Thus, in addition to the time for blowing the steam into the mold 1 and heating the coated sand 2, it is necessary to supply and fill the coated sand 2 into the mold 1. Although the time for curing or solidifying the binder can be shortened by heating, the entire process time required to mold the mold is not short enough to be sufficiently satisfied. .

  The present invention has been made in view of the above points, and an object of the present invention is to provide a method for producing a mold that can shorten the time of the process of forming the mold.

  In the mold manufacturing method according to the present invention, a coated sand 2 prepared by containing a binder and a refractory aggregate is supplied and filled in a mold 1, and the mold 1 filled with the coated sand 2 is steamed. When the coated sand 2 is heated by heating the coated sand 2, the coated sand 2 is supplied into the mold 1 while steam is blown into the mold 1 at the same time.

  Thus, while supplying the coated sand 2 into the mold 1, the steam is blown into the mold 1 while the coated sand 2 is being supplied into the mold 1 by simultaneously blowing the steam into the mold 1. The coated sand 2 can be heated with water vapor, the time required for curing or solidifying the binder of the coated sand 2 filled in the mold 1 can be shortened, and the process of molding the mold can be performed. Time can be shortened.

  Further, the present invention is characterized in that by feeding the coated sand 2 into the mold 1 with the pressure of water vapor, the coated sand 2 is supplied into the mold 1 and at the same time, water vapor is blown into the mold 1. is there.

  According to this method, the coated sand 2 can be supplied into the mold 1 using the pressure of water vapor, and no separate power is required to supply the coated sand 2 into the mold 1. It is something that can be done.

  In the present invention, the water vapor supply path 4 is formed so as to surround the sand supply path 3 for supplying the coated sand 2 into the mold 1, and the coated sand 2 is supplied into the mold 1 from the sand supply path 3 while simultaneously Water vapor is blown into the mold 1 from the supply path 4.

  According to this method, the coated sand 2 supplied from the sand supply path 3 can be filled in the mold 1 while uniformly mixing the water vapor discharged from the water vapor supply path 4 with the coated sand 2. Can be heated uniformly.

  Further, the present invention forms a sand supply path 3 for supplying the coated sand 2 into the mold 1 so as to surround the water vapor supply path 4, and simultaneously supplies the coated sand 2 from the sand supply path 3 into the mold 1. It is characterized in that water vapor is blown into the mold 1 from the water vapor supply path 4.

  According to this method, the coated sand 2 supplied from the sand supply path 3 can be filled in the mold 1 while uniformly mixing the water vapor discharged from the water vapor supply path 4 with the coated sand 2. Can be heated uniformly.

  In addition, the present invention is characterized in that water vapor blown into the mold 1 is sucked and forced out of the mold 1 while water vapor is blown into the mold 1.

  By forcibly discharging the water vapor out of the mold 1 in this way, the water vapor does not stay in the mold 1, the efficiency of heating with water vapor is increased, and the mold can be manufactured in a shorter time. It is.

  Further, the present invention is characterized in that water vapor having a pressure of 0.1275 MPa or more is blown into the mold.

  By blowing water vapor into the mold 1 at such a pressure, it is possible to distribute the water vapor throughout the coated sand 2 filled in the mold 1, and the coated sand 1 is uniformly heated to form a homogeneous mold. Can be manufactured.

  The present invention is also characterized in that the water vapor blown into the mold 1 is superheated water vapor.

  The superheated steam is a high-temperature dry steam. By using the superheated steam as the steam, the condensed water is hardly generated from the steam in the mold 1 and the temperature of the coated sand 2 in the mold 1 is increased. The speed of the can be increased.

  Further, the present invention is characterized in that the coated sand 2 is preheated and then supplied and filled into the mold 1.

  When steam is blown into the mold 1 and the coated sand 2 is heated with latent heat, the amount of latent heat lost to the coated sand 2 can be reduced, and the generation of condensed water from the steam can be suppressed. The speed at which the temperature in the mold 1 is raised to a temperature equal to or higher than the temperature at which the second binder is solidified or cured can be increased.

  Further, the present invention is characterized in that the heated mold 1 is filled with the coated sand 2.

  By heating the mold 1 in this manner, it is possible to suppress the water vapor blown into the mold 1 from being cooled and to generate condensed water, and to increase the speed at which the temperature of the coated sand 2 in the mold 1 is increased. It is something that can be done.

  In the present invention, the binder of the coated sand is a thermosetting resin.

  According to this invention, the fireproof aggregate can be consolidated by the thermosetting resin, and a mold having a high bond strength of the fireproof aggregate can be obtained.

  Further, the present invention is characterized in that the binder of the coated sand 2 is a saccharide.

  According to the present invention, the refractory aggregate can be consolidated using saccharides as a binder, and saccharides release carbon dioxide and water even when thermally decomposed, so that toxic gases are released. Therefore, a mold that does not pollute the environment can be manufactured. Moreover, saccharides are easily decomposed by heating, and a mold having good disintegration can be obtained.

  According to the present invention, the steam is blown into the mold while the coated sand is being fed into the mold while the coated sand is being fed into the mold. The coated sand can be heated with water vapor, the time required to cure or solidify the binder of the coated sand filled in the mold can be shortened, and the time for molding the mold can be reduced. It can be shortened.

An example of embodiment of this invention is shown, (a) (b) is a schematic sectional drawing in each process, respectively. It is a schematic sectional drawing which shows an example of other embodiment of this invention. It is a schematic sectional drawing which shows an example of other embodiment of this invention. It is a schematic sectional drawing which shows an example of other embodiment of this invention. A prior art example is shown, (a) thru | or (c) is a schematic sectional drawing, respectively.

  Embodiments of the present invention will be described below.

  The coated sand is formed by coating the surface of the refractory aggregate with the binder by mixing the binder with the refractory aggregate.

  The refractory aggregate is not particularly limited, and can be exemplified by 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 two or more.

  As the binder, a thermosetting resin is generally used, but a saccharide can also be used. You may make it use a thermosetting resin and saccharides together as a binder.

  Examples of the thermosetting resin used for the binder include phenol resins such as resol type, novolac type, and benzylic ether type, furan resin, isocyanate compound, amine polyol resin, polyether polyol resin, and the like. These can be combined with isocyanate compounds, organic esters, hexamethylenetetramine, etc. as curing agents, and tertiary amines, pyridine derivatives, organic sulfonic acids, etc. as curing catalysts, and can be used with thermosetting properties. It is. Among these, a phenol resin is preferable.

  The phenol resin can be prepared by reacting phenols and formaldehyde in the presence of a reaction catalyst.

  Here, the phenols mean phenol and phenol derivatives. For example, in addition to phenol, trifunctional compounds such as m-cresol, resorcinol, 3,5-xylenol, bisphenol A, dihydroxydiphenylmethane, etc. Tetrafunctional, bifunctional such as o-cresol, p-cresol, p-ter-butylphenol, p-phenylphenol, p-cumylphenol, p-nonylphenol, 2,4 or 2,6-xylenol An o- or p-substituted phenol can be mentioned, and a halogenated phenol substituted with chlorine or bromine can also be used. Of course, one type can be selected and used, or a plurality of types can be mixed and used.

  As formaldehydes, formalin, which is in the form of an aqueous solution, is optimal, but forms such as paraformaldehyde, acetaldehyde, benzaldehyde, trioxane, and tetraoxane can also be used. It can also be used by replacing with furyl alcohol.

  The blending ratio of the above phenols and formaldehyde is preferably set so that the molar ratio of phenols to formaldehyde is in the range of 1: 0.6 to 1: 3.5.

  When preparing a novolak type phenolic resin, the reaction catalyst is an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid, or an organic acid such as oxalic acid, paratoluenesulfonic acid, benzenesulfonic acid or xylenesulfonic acid, or zinc acetate. Can be used. Moreover, when preparing a resol type phenol resin, an alkaline earth metal oxide or hydroxide can be used, and aliphatic dimethylamine, triethylamine, butylamine, dibutylamine, tributylamine, diethylenetriamine, dicyandiamide and the like can be used. Primary amine, secondary amine, tertiary amine, aliphatic amines having aromatic rings such as N, N-dimethylbenzylamine, aromatic amines such as aniline and 1,5-naphthalenediamine, ammonia, hexamethylenetetramine, etc. In addition, other divalent metal naphthenic acids, divalent metal hydroxides, and the like can also be used.

  When the phenol resin binder is diluted and used, alcohols, ketones, esters, polyhydric alcohols, and the like can be used as a solvent for dilution.

  In addition, as the saccharides used in the binder, monosaccharides, oligosaccharides, polysaccharides can be used, and one type selected from various monosaccharides, oligosaccharides, polysaccharides and used alone, Multiple types can be selected and used together.

  Although it does not specifically limit as monosaccharide, 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, cellulose, starch, etc., and one of these can be selected or used in combination of two or more. it can. 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 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, enzyme modified Dextrin, acid treatment starches, those low molecular weight as oxidized starch, and low viscosity, such as cross-linked starch starches are preferred.

  The binder may contain a carboxylic acid as a curing agent for saccharides, particularly polysaccharides. The carboxylic acid is not particularly limited, and examples thereof include oxalic acid, maleic acid, succinic acid, citric acid, butanetetradicarboxylic acid, methyl vinyl ether-maleic anhydride copolymer, and the like. The content of the carboxylic acid in the binder is preferably such that the amount of the carboxylic acid 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.

  Furthermore, in order to improve the fluidity of the coated sand, the binder may contain a lubricant. 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, and 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.

  Then, by coating the refractory aggregate particles with a binder or lubricant and mixing them, the coating layer containing the binder can be coated on the surface of the refractory aggregate to obtain a coated sand. It is. The amount of the binder to be coated on the refractory aggregate differs depending on the component and application and cannot be specified unconditionally. It is generally preferable to set the lubricant so that the solid content is in the range of 0.02 to 0.15 parts by mass. Examples of a method for coating the surface of the refractory aggregate with a binder 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 while maintaining the mixing, thereby obtaining a granular and free-flowing coated sand. Alternatively, it is a method of obtaining coated sand by mixing and coating a refractory aggregate heated to 110 to 180 ° C. with a binder dissolved or dispersed in a solvent such as water and volatilizing the solvent.

  The cold coating method is a method of obtaining a coated sand by dissolving a binder in a solvent such as water or methanol to form a liquid, adding this to the particles of the refractory aggregate, mixing, and volatilizing the solvent. is there.

  The semi-hot coating method is a method of obtaining a coated sand by adding a binder dissolved in the above-mentioned solvent to refractory aggregate particles heated to 50 to 90 ° C. and mixing them to volatilize the solvent.

  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. This is a method for obtaining coated sand.

  In any of the above methods, the surface of the refractory aggregate can be coated with a coating layer made of a solid binder at room temperature (30 ° C.) to obtain a granular coated sand, but workability, etc. 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.

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

  Next, an example of a method for producing a mold using the coated sand prepared as described above will be described with reference to FIG.

  The mold 1 is formed by providing a cavity 10 therein, and the mold 1 is configured to be able to open, for example, vertically or horizontally. An injection port 11 is provided on the upper surface of the mold 1, and an exhaust port 13 closed with a net 12 such as a metal net is provided on the lower surface of the mold 1. A hopper 21 can be connected to the injection port 11 of the mold 1 by a nozzle port 22 at the lower end thereof. A steam supply pipe 23 is connected to the upper part of the hopper 21, and steam generated in a steam generator 29 such as a boiler is supplied into the hopper 21 by opening a cock 24 provided in the steam supply pipe 23. It is made to be able to. A sand storage tank 25 is connected to the upper end of the hopper 21 by a sand supply pipe 26. By opening a cock 27 provided in the sand supply pipe 26, the coated sand 2 stored in the sand storage tank 25 is sanded. The hopper 21 is supplied through the supply pipe 26.

  Then, the nozzle port 22 of the hopper 21 is connected to the injection port 11 of the mold 1, and the sand storage tank 25 is first opened by opening the cock 27 of the sand supply pipe 26 with the cock 24 of the steam supply pipe 23 closed. The coated sand 2 stored in the inside is supplied to the hopper 21 as shown in FIG. At this time, an amount of the coated sand 2 necessary for filling the cavity 10 of the mold 1 is supplied to the hopper 21.

  Next, the cock 27 of the sand supply pipe 26 is closed and the cock 24 of the steam supply pipe 23 is opened, and steam is supplied and blown into the hopper 21 through the steam supply pipe 23. When water vapor is supplied and blown into the hopper 21 in this way, the inside of the hopper 21 is pressurized with the pressure of the water vapor, and the coated sand 2 in the hopper 21 is pushed out from the nozzle port 22, and from the injection port 11 to the mold 1. As shown in FIG. 1B, the mold 1 can be filled with the coated sand 2 by being blown into the cavity 10. Thus, using the pressure of water vapor, the coated sand 2 can be supplied and filled into the mold 1, and a special apparatus for filling the coated sand 2 into the mold 1 is not required. It is something that can be done. Since the exhaust port 13 is blocked by the net 12, the coated sand 2 does not leak from the exhaust port 13.

  Even after the coated sand 2 is filled in the mold 1 as described above, the state in which the cock 24 of the steam supply pipe 23 is opened is continued, and the steam 1 is supplied from the steam supply pipe 23 through the hopper 21 into the mold 1. Steam is blown. When steam is blown into the mold 1 and the steam contacts the surface of the coated sand 2, the coated sand 2 can be directly heated by the high latent heat of the steam, and the temperature of the coated sand 2 is about 100 ° C. Rising rapidly. In addition, the water vapor penetrates between the particles of the coated sand 2 and penetrates the entire inside of the mold 1 so that the coated sand 2 in the mold 1 can be heated to a uniform temperature. The water vapor blown into the mold 1 from the injection port 11 is exhausted from the exhaust port 13 after heating the coated sand 2 in the mold 1.

  In this way, the coated sand 2 can be rapidly heated by the latent heat of the steam blown into the mold 1 so that the binder of the coated sand 2 can be solidified or cured in a short time. In addition, since the coated sand 2 is filled in the mold 1 using the pressure of water vapor, the steam begins to be blown into the mold 1 together with the coated sand 2 from the time when the coated sand 2 is supplied to the mold 1. Yes. That is, while supplying the coated sand 2 into the mold 1, water vapor is blown into the mold 1 at the same time, and the coated sand 2 is heated with water vapor during the process of filling the coated sand 2 into the mold 1. Has been. Accordingly, it is possible to shorten the time required for solidifying or curing the binder by heating the binder of the coated sand 2 filled in the mold 1 with the steam blown into the mold 1. Yes, the molding time of the mold A from the start of supplying the coated sand 2 to the mold 1 until the binder A of the coated sand 2 in the mold 1 is solidified or cured to mold the mold A can be shortened. Is.

  After forming the mold A in the mold 1 in this manner, the mold A can be obtained by closing the cock 24 of the water vapor supply pipe 23 and then opening the mold 1 to remove the mold A. Then, after this, the mold 1 is closed again, and the process returns to the beginning of the above-described process. The mold A can be manufactured in a cycle up to this point. Of course, the present invention is not limited to this. After the mold A is formed in the mold 1, the mold 1 is removed from the hopper 21 and moved to the step of removing the mold A, and the cavity 10 is emptied. By connecting the different mold 1 to the hopper 21, the mold A can be manufactured in one cycle until returning to the beginning of the above process.

  FIG. 2 shows an example of another embodiment, in which a suction pipe 32 is connected to the exhaust port 13 of the mold 1. A vacuum pump or the like is connected to the suction pipe 32, and water vapor is blown into the mold 1 as described above while sucking the mold 1 with the suction pipe 12. By blowing water vapor while sucking the inside of the mold 1 in this way, the water vapor is forcibly discharged from the exhaust port 13 after passing between the particles of the coated sand 2 filled in the mold 1. Water vapor does not stay in the mold 1, heating efficiency with the water vapor increases, and the mold A can be manufactured in a shorter time.

  FIG. 3 shows an example of another embodiment of the present invention. A sand supply path 3 is provided at a lower end of the sand storage tank 25, and an air supply pipe 34 is connected to the sand storage tank 25 so as to pressurize the sand storage tank 25 with air pressure. A cock 35 is provided in the sand supply path 3, and the coated sand 2 in the sand storage tank 25 can be sent out through the sand supply path 3 by opening the cock 35. A steam supply path 4 is provided on the outer periphery of the sand supply path 3. The sand supply path 3 and the water vapor supply path 4 are each formed of a pipe or the like, and are formed in a double pipe shape surrounding the outer periphery of the sand supply path 3 with the water vapor supply path 4. A steam supply pipe 23 is connected to the steam supply path 4, and steam generated by a steam generator 29 such as a boiler is supplied to the steam supply path 4 by opening a cock 24 provided in the steam supply pipe 23. It is made to be able to. The lower end opening of the sand supply path 3 and the lower end opening of the water vapor supply path 4 are formed concentrically to form a nozzle port 36.

  The mold 1 is formed in the same manner as in the above embodiment. The nozzle port 36 is connected to the inlet 11, the cock 35 of the sand supply path 3 is opened, and the cock 24 of the water vapor supply pipe 23 is connected. open. Then, the coated sand 2 stored in the sand storage tank 25 passes through the sand supply path 3 and is blown into the mold 1 from the injection port 11. At this time, water vapor is injected from the injection port 11 to the mold 1 through the water vapor supply path 4. Be blown into. After the coated sand 2 is blown into the mold 1 and the interior of the mold 1 is filled with the coated sand 2, the cock 35 of the sand supply path 3 is closed to stop the supply of the coated sand 2. Even after the cock 35 is closed in this way, the steam 24 is blown into the mold 1 from the steam supply path 4 by continuing the state in which the cock 24 of the steam supply pipe 23 is opened, and the mold 1 is filled. The coated sand 2 can be heated with steam to produce the mold A.

  Also in this embodiment, while supplying the coated sand 2 from the sand supply path 3 into the mold 1, water vapor is simultaneously blown into the mold 1 from the water vapor supply path 4. The coated sand 2 is heated with water vapor even during the step of filling. Accordingly, it is possible to shorten the time required for solidifying or curing the binder by heating the binder of the coated sand 2 filled in the mold 1 with the steam blown into the mold 1. Yes, the molding time of the mold A from the start of supplying the coated sand 2 to the mold 1 until the binder A of the coated sand 2 in the mold 1 is solidified or cured to mold the mold A can be shortened. Is. Further, at this time, the coated sand 2 can be filled into the mold 1 while the steam discharged from the steam supply path 4 is uniformly mixed with the coated sand 2 supplied from the sand supply path 3. The sand 2 can be heated uniformly to obtain a homogeneous mold A.

  FIG. 4 shows an example of another embodiment of the present invention. A sand supply path 3 is provided in a suspended manner at the lower end of the sand storage tank 25. A water vapor supply path 4 is provided in the sand supply path 3, that is, a double pipe shape is formed so that the outer periphery of the water vapor supply path 4 is surrounded by the sand supply path 3. A steam supply pipe 23 is connected to the steam supply path 4, and steam generated by a steam generator 29 such as a boiler is supplied to the steam supply path 4 by opening a cock 24 provided in the steam supply pipe 23. It is made to be able to. The lower end opening of the water vapor supply path 4 is formed as an ejector nozzle 38 with a reduced inner diameter. Further, the lower end opening of the sand supply passage 3 is positioned so as to protrude slightly below the ejector nozzle 38, and the inner diameter is similarly reduced to form a nozzle port 39.

  The configuration of the mold 1 is the same as described above. When the nozzle port 39 is connected to the injection port 11 of the mold 1 and the cock 24 of the steam supply pipe 23 is opened, the steam supplied from the steam supply pipe 23 to the steam supply path 4 is Is blown into the mold 1 from the ejector nozzle 38 as a high-speed flow. When the water vapor passes through the ejector nozzle 38 at a high speed in this way, the pressure in the nozzle port 39 of the sand supply path 3 becomes negative due to the venturi effect, and the coated sand 2 in the sand storage tank 25 moves to the sand supply path 3. The coated sand 2 is also blown into the mold 1 along with the flow of water vapor that is sucked and blown into the mold 1 from the ejector nozzle 38. In this way, the coated sand 2 can be supplied and filled into the mold 1 using water vapor, and a special device for filling the coated sand 2 into the mold 1 can be dispensed with. Is. And, after the coated sand 2 is filled in the mold 1, by continuing the supply of water vapor into the mold 1, the coated sand 2 in the mold 1 can be heated with water vapor to produce a mold. It is.

  Also in this embodiment, while supplying the coated sand 2 from the sand supply path 3 into the mold 1, water vapor is simultaneously blown into the mold 1 from the water vapor supply path 4. The coated sand 2 is heated with water vapor even during the step of filling. Therefore, after filling the coated sand 2 into the mold 1, the time required to solidify or cure the binder by blowing water vapor into the mold 1 and heating the coated sand 2 can be shortened. It is possible to shorten the molding time of the mold A from the start of supplying the coated sand 2 to the mold 1 until the binder A of the coated sand 2 in the mold 1 is solidified or cured to mold the mold A. It can be done. At this time, since the coated sand 2 supplied from the sand supply path 3 is supplied into the mold 1 by the water vapor discharged from the water vapor supply path 4, while uniformly mixing the water vapor with the coated sand 2, The coated sand 2 can be filled in the mold 1, and the coated sand 2 can be uniformly heated to obtain a homogeneous mold A.

  Here, as the water vapor in the present invention, saturated water vapor generated in a water vapor generator 29 such as a boiler can be used as it is, but it is preferable to use superheated water vapor. The superheated steam is a steam in a complete gas state in which the saturated steam generated by the steam generator 29 is further heated by the superheater 30 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 is not particularly limited, and the temperature of the superheated steam can be increased to about 900 ° C., and therefore, the temperature may be set between 100 and 900 ° C. as necessary. As shown in the embodiment of FIGS. 1 to 4, by connecting the heater 3 to the steam supply pipe 23, superheated steam can be easily generated and supplied to the mold 3.

  The steam is preferably blown into the mold 1 at a pressure of 0.1275 MPa (0.2 MPa in terms of the gauge pressure of the steam delivered from the steam generator 29) or more. By blowing water vapor of such pressure into the mold 1, it becomes easy to spread the water vapor throughout the coated sand 2 filled in the mold 1, and the coated sand 2 in the mold 1 is made uniform. A homogeneous mold can be produced by heating. The upper limit of the water vapor pressure is not particularly set, but about 0.6 MPa is a practical upper limit.

  As the water vapor, a mixed gas with air can also be used. When condensed water is generated by cooling, the volume of water vapor rapidly decreases and the pressure decreases. For this reason, when water vapor is used alone, it is difficult for water vapor to reach the back of the mold 1 when the pressure is reduced due to the volume reduction due to the generation of condensed water. On the other hand, when water vapor is mixed with air, the water vapor can be spread to the back of the mold 1 by the pressure of the air, and the coated sand 2 filled in the mold 1 is heated uniformly. It is something that can be done.

  In the present invention, the coated sand 2 is preferably preheated and supplied to the mold 1. This preheating is performed by heating with an electric heater, heating with hot air generated by exchanging water vapor, heating with hot air generated by gas combustion or oil combustion, or by electromagnetic induction (IH). Heating can be performed by any method. The pre-heated coated sand 2 may be supplied to the hopper 21 and the sand storage tank 25, but the pre-heating of the coated sand 2 may be performed in the hopper 21 and the sand storage tank 25.

  For example, a heat exchanger can be attached to the hopper 21 or the sand storage tank 25, and the coated sand 2 in the hopper 21 or the sand storage tank 25 can be preheated with the heat exchanger. At this time, in the present invention, as described above, the steam generator 29 for generating the steam for heating the coated sand 2 in the mold 1 is provided. Therefore, the steam generated from the steam generator 29 is passed through the heat exchanger to be coated. If the sand 2 is preheated, there is no need to separately provide a heating source for preheating the coated sand 2.

  Here, as described above, when steam is blown into the mold 1 to heat the coated sand 2, the temperature of the coated sand 2 can be rapidly increased to about 100 ° C. by the latent heat of the steam. Is taken by the coated sand 2 to condense the water vapor and produce condensed water in the mold 1. And in order to raise the coated sand 2 to the temperature of 100 degreeC or more, it is necessary to evaporate this condensed water. The condensed water is evaporated by heating with water vapor blown thereafter, but the efficiency of evaporating the condensed water is low. On the other hand, when the coated sand 2 filled in the mold 1 is preheated in this way, the amount of latent heat of the water vapor taken away by the coated sand 2 can be reduced. It is possible to reduce the amount of condensed water produced by depriving of water. Thus, the amount of condensed water generated in the mold 1 is small, and the condensed water can be rapidly evaporated by the latent heat of steam blown later, and the temperature can be raised to 100 ° C. or higher in a short time. It can be raised.

  The temperature at which the coated sand 2 is preheated is not particularly limited as long as it is normal temperature or higher. However, when a thermosetting resin is used as the binder for the coated sand 2, the thermosetting resin is cured. It is desirable to be below the temperature at which to start. In particular, when the thermosetting resin of the binder is a phenol resin, it is desirable that the preheating temperature is equal to or lower than the fusion point because the coated sand 2 can be easily blown into the mold 1.

  As described above, the preheating temperature of the coated sand 2 may be normal temperature or higher, but if the preheating temperature is 30 ° C. or higher, a change in the manufacturing conditions due to the season is reduced and the mold is manufactured with stable quality. It can also be done. That is, conventionally, the coated sand 2 is generally used at the atmospheric temperature, and since the atmospheric temperature in summer and the atmospheric temperature in winter are greatly different, the temperature of the coated sand 2 is greatly different in summer and winter. As it is used, the production conditions vary greatly depending on the season, and it is difficult to produce a mold with stable quality. Therefore, if the preheating temperature is set to 30 ° C. or higher, the temperature of the coated sand 2 can be made the same in both winter and summer, and the change in production conditions due to the season is reduced. Thus, the mold can be manufactured with stable quality.

  Moreover, when the preheating temperature of the coated sand 2 is 50 ° C. or higher, it is possible to obtain a high effect of reducing the generation of condensed water in the mold 1, and the condensed water generated in the mold 1 can be quickly recovered. It is possible to increase the speed of temperature rise in the mold 1 by evaporation.

  Further, when the preheating temperature of the coated sand 2 is 100 ° C. or higher, it is possible to prevent almost all condensed water from being generated in the mold 1, and the speed of temperature rise in the mold 1 can be further increased. It is.

  Further, as described above, steam may be blown into the mold 1 to heat the coated sand 2, and after the temperature of the coated sand 2 has risen to around 100 ° C., 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. 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 as long as it is 100 ° C. or higher and is higher than the temperature at which the binder of the coated sand 2 is solidified or cured.

  When the heated gas is blown into the mold 1 in this way, the heated gas contains less moisture than water vapor and is a dry gas having a low humidity. Therefore, the condensed water generated as described above in the mold 1 is used. It can be evaporated and dried in a short time. Here, when the water evaporation experiment was performed with the air flow of superheated steam and heated air, the evaporation of water into the heated air becomes larger than the evaporation rate of water into the superheated steam at a temperature below 170 ° C. (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 coated sand 2 can be increased to 100 ° C. or more in a shorter time, and a mold having high strength can be produced in a short heating time.

  In addition, when the condensed water is heated and evaporated as described above, the volume of the water vapor is reduced due to the condensation, the pressure decreases, the condensed water stays in the mold 1, and drying or temperature increase occurs. 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 coated sand 2 in the mold 1, the amount of condensed water in the mold 1, etc. The short time is 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.

  In the present invention, the mold 1 may be preheated and the pre-heated mold 1 may be filled with the coated sand 2. If the mold 1 is preheated in this way, it is possible to reduce the latent heat of the steam blown into the mold 1 from being taken away by the mold 1, and the effect of reducing the generation of condensed water is further enhanced. It can be obtained, and the speed of temperature rise in the mold 1 can be further increased. The heating temperature of the mold 1 is set to 70 ° C. or higher. The upper limit of the heating temperature of the mold 1 is not particularly limited, but is practically about 250 ° C.

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

Example 1
A mold was manufactured using the apparatus shown in FIG.

  The cavity 10 of the mold 1 has a size of 30 cm × 10 cm × 4 cm, and was used by heating to 150 ° C.

  The hopper 21 was connected to a steam generator 29 made of a boiler and a superheater (“GE-100” manufactured by Nomura Engineering Co., Ltd.) 30. The steam generator 29 generates saturated steam at a gauge pressure of 0.4 MPa and a temperature of 143 ° C., and the superheater 30 heats the saturated steam to 80 kg / h as superheated steam at 350 ° C. and 0.45 MPa. Is supplied at a flow rate of.

  In the sand storage tank 25, the coated sand 2 obtained as follows was stored. First, 30 kg of flattery sand heated to 145 ° C. was placed in a whirl mixer, 540 g of a resol type phenolic resin (“LT-15” manufactured by Lignite Co., Ltd.) was added thereto, kneaded for 30 seconds, and then 450 g of water was added And kneaded thoroughly. Next, 30 g of calcium stearate was further added and kneaded for 30 seconds, followed by aeration to obtain resin-coated sand 2 to which 1.8% by mass of a phenol resin having a fusion point of 108 ° C. adhered as a binder.

  Then, the nozzle port 22 of the hopper 21 is connected to the injection port 11 on the upper surface of the mold 1. First, the cock 27 of the sand supply pipe 26 is opened, and the coated sand 2 in the sand storage tank 25 is supplied to the hopper 21 by 2.1 kg. Supplied. Thus, the time required to supply 2.1 kg of coated sand 2 to the hopper 21 was 2 seconds.

  Next, after closing the cock 27 of the sand supply pipe 26, the superheated steam was supplied into the hopper 21 by opening the cock 24 of the steam supply pipe 23. Thus, by supplying and blowing water vapor into the hopper 21, the coated sand 2 in the hopper 21 was blown into the cavity 10 of the mold 1, and the coated sand 2 was filled in the mold 1. Thus, the time required to fill the coated sand 2 into the mold 1 was 6 seconds.

  Here, the time from opening the cock 24 of the steam supply pipe 23 to closing it is set to 17 seconds, and after the coated sand 2 is filled in the mold 1, the superheated steam is blown into the mold 1. Continued. Then, after closing the cock 24 of the water vapor supply pipe 23, the mold 1 was opened to obtain a casting mold having a size of 30 cm × 10 cm × 4 cm.

  Therefore, in Example 1, the total time required for mold making was 19 seconds.

(Examples 2 to 4)
The time from opening to closing of the cock 24 of the water vapor supply pipe 23 is set to 12 seconds in the second embodiment, 22 seconds in the third embodiment, and 27 seconds in the fourth embodiment. Thus, a mold was obtained.

  Therefore, the total time required for mold making was 14 seconds in Example 2, 24 seconds in Example 3, and 29 seconds in Example 4.

(Examples 5-7)
The coated sand 2 was obtained as follows. 30 kg of flattered cinnabar sand heated to 130 ° C. was placed in a whirl mixer, and an aqueous solution in which 600 g of dextrin (“ND-S” manufactured by Nissho Kagaku Co., Ltd.) was dissolved or dispersed in 450 g of water was added thereto 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 to obtain a coated sand having 2.0% by mass of saccharide as a binder.

  The time from opening the cock 24 of the water vapor supply pipe 23 to closing it is set to 17 seconds in the fifth embodiment, 22 seconds in the sixth embodiment, and 27 seconds in the seventh embodiment. In the same manner, a template was obtained.

  Therefore, the total time required for mold making was 19 seconds in Example 5, 24 seconds in Example 6, and 29 seconds in Example 7.

(Comparative Examples 1-2)
A mold was manufactured using the apparatus shown in FIG. The configuration of the mold 1 is the same as that of FIG. Further, as the coated sand 2, the same resin-coated sand 2 with a phenol resin as a binder was used as in Example 1.

  First, as shown in FIGS. 5A and 5B, a hopper 14 is connected to the mold 1, 2.1 kg of coated sand 2 is supplied from the hopper 14 into the mold 1, and the coated sand 2 is put into the mold 1. Filled. Thus, the time required to fill the coated sand 2 into the mold 1 was 6 seconds.

  Next, as shown in FIG. 5C, the steam pipe 19 was connected to the mold 1, the cock 18 was opened, and superheated steam was blown into the mold 1. The conditions for supplying superheated steam are the same as in Example 1. Then, the time from opening the cock 24 of the steam supply pipe 23 to closing it is set to 13 seconds in the comparative example 1 and 17 seconds in the comparative example 2, and superheated steam is blown into the mold 1 so that the cock of the steam pipe 19 After closing 18, the mold 1 was opened to obtain a mold formed into a size of 30 cm × 10 cm × 4 cm.

  Therefore, the total time required for molding the mold was 19 seconds in Comparative Example 1 and 23 seconds in Comparative Example 2.

(Comparative Examples 3-4)
A mold was manufactured using the apparatus shown in FIG. Also, as the coated sand 2, the same resin coated sand 2 with saccharides attached as a binder was used as in Examples 5-6.

  Then, the time from opening the cock 24 of the steam supply pipe 23 to closing it is set to 13 seconds in the comparative example 3 and 17 seconds in the comparative example 4, and the same as in the comparative examples 1 and 2 described above. Thus, a mold was obtained.

  Therefore, the total time required for molding the mold was 19 seconds in Comparative Example 3 and 23 seconds in Comparative Example 4.

  About the casting_mold | template obtained by said Examples 1-7 and Comparative Examples 1-4, mass and bending strength were measured. The bending strength was measured according to JIS K6910. The results are shown in Table 1.

実施例１と比較例１の比較、及び実施例５と比較例３の比較から明らかなように、鋳型の造型時間が等しくなるように設定すると、比較例１や比較例３では水蒸気の吹き込み時間が短くなるため、鋳型の強度が低下した。一方、実施例１と比較例２の比較、及び実施例５と比較例４の比較から明らかなように、鋳型の強度が同じになるように水蒸気の吹き込み時間を同じに設定すると、比較例２や比較例４では鋳型の造型時間が長くなった。

As is clear from the comparison between Example 1 and Comparative Example 1 and the comparison between Example 5 and Comparative Example 3, when the molding times of the molds are set to be equal, in Comparative Example 1 and Comparative Example 3, the steam blowing time is set. , The mold strength decreased. On the other hand, as is clear from the comparison between Example 1 and Comparative Example 2 and the comparison between Example 5 and Comparative Example 4, when the water vapor blowing time is set to be the same so that the molds have the same strength, Comparative Example 2 In Comparative Example 4, the molding time for the mold became longer.

  In the apparatus of FIG. 5, from the state of FIG. 5 (b) in which the hopper 14 is connected to the mold 1, the steam pipe 19 is connected to the mold 1 as shown in FIG. 5 (c). Therefore, in Comparative Examples 1 to 4, the molding time of the mold was actually 20 seconds longer than the time in Table 1.

  As can be seen from Table 1, in each example, a mold having bending strength equal to or higher than that of the comparative example can be obtained even if the molding time of the mold is shortened. .

1 type 2 coated sand 3 sand supply path 4 water vapor supply path

Claims (11)

  Coated sand prepared containing a binder and refractory aggregate is supplied and filled into the mold, and steam is blown into the mold filled with the coated sand to heat the coated sand to produce a mold. In this case, a method for producing a mold is characterized in that water is blown into the mold at the same time as the coated sand is supplied into the mold.   The method for producing a mold according to claim 1, wherein the coated sand is fed into the mold by the pressure of water vapor so that the coated sand is supplied into the mold and at the same time the water vapor is blown into the mold.   A water vapor supply path was formed so as to surround the sand supply path for supplying the coated sand into the mold, and while supplying the coated sand from the sand supply path into the mold, water vapor was blown into the mold from the water vapor supply path at the same time. The method for producing a mold according to claim 1.   Form a sand supply path for supplying the coated sand into the mold so as to surround the steam supply path, and supply the coated sand from the sand supply path into the mold, and at the same time, blow steam into the mold from the steam supply path The method for producing a mold according to claim 1, wherein:   The method for producing a mold according to any one of claims 1 to 4, wherein the water vapor blown into the mold is sucked into the mold and forcibly discharged out of the mold.   The method for producing a mold according to any one of claims 1 to 5, wherein water vapor having a pressure of 0.1275 MPa or more is blown into the mold.   The method for producing a mold according to any one of claims 1 to 6, wherein the water vapor is superheated water vapor.   The method for producing a mold according to any one of claims 1 to 7, wherein the coated sand is preheated and then supplied and filled in a mold.   The method for producing a mold according to any one of claims 1 to 8, wherein the coated mold is filled in a heated mold.   The method for producing a mold according to any one of claims 1 to 9, wherein the binder of the coated sand is a thermosetting resin.   The method for producing a mold according to any one of claims 1 to 10, wherein the binder of the coated sand is a saccharide.

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