JP4451813B2 - Cast iron mold and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cast iron mold in which a steel pipe for temperature control is cast and a manufacturing method thereof.

  In cast iron castings that cast steel pipes for temperature control, such as cooling staves for metallurgical furnaces such as blast furnaces and molds for resin molding machines, various methods are known and practically used to prevent carburization of cast steel pipes. It has become.

  For example, regarding a means for manufacturing a cast iron casting in which a cooling pipe is embedded by a cast fill, such as a cooling stave for cooling a furnace wall refractory, without causing damage or cracks in the pipe, The following technologies have been proposed.

  A metal pipe of a predetermined shape filled with collapsible sand is placed in the cavity of the mold, the metal pipe is cast with the molten metal injected into the cavity, and the collapsible sand remaining after cooling and solidification is collapsed and removed, and then heated and cooled. What forms a medium passage hole is known (for example, refer patent document 1).

  A heat-resistant and corrosion-resistant pipe (made of stainless steel) is positioned and fixed in a mold, and a molten metal is poured and cast in a state in which a pressurized cooling gas flows in the pipe (for example, see Patent Document 2). .

  The invention relates to a cooling stave provided with a non-fused double cooling pipe, and after forming an alumina film with a thickness of 0.08 to 0.25 mm on the outside of the drawn double steel pipe, it is cast with spheroidal graphite cast iron Is known (see, for example, Patent Document 3).

  A cooling pipe, and a coating layer (first layer) of at least one aggregate of silica, chromite, alumina, zircon, caking additive, and water is formed on the outer surface of the cooling pipe; On top of that, a composite oxide such as silica, alumina and the like blended so that the hemispheric point temperature is 1200 to 1400 ° C. is used as a main aggregate, and a slurry containing a caking additive and water (second layer). The thing which apply | coats is known. By superimposing the second layer on the first layer, when the base metal is poured, the second layer softens and penetrates into 40% of the pores of the first layer, and the cooling pipe from the base metal. The carburization of carbon is prevented (see, for example, Patent Document 4).

  A refractory material such as siliceous, chrome, chamotte, magnesia, dolomite, etc. and water glass are blended and coated on a metal tube (for example, see Patent Document 5).

There is known a heat exchanger in which a metal cooling pipe in which a coating layer made of aluminum nitride or alumina and an inorganic refractory having a melting point of 1300 ° C. or less is formed on the outer surface is cast on a base material (for example, Patent Documents) 6). In this case, when the molten metal is cast, the inorganic refractory melts into a glass and penetrates between aluminum nitride or alumina.
JP-A-6-320252 Japanese Utility Model Publication No. 6-38592 Japanese Patent Publication No. 58-49607 Japanese Patent Publication No. 60-31588 Japanese Examined Patent Publication No. 54-44650 Japanese Patent Laid-Open No. 03-226343

  In Patent Document 1, the shape of the pipe is restricted because it is necessary to remove the sand for casting, and the carbon of the high-temperature molten metal is carburized into the steel pipe when pouring the high-temperature molten metal for cast iron casting. And this pipe may melt.

  In the case of a casting mold in which a stainless pipe is cast in the one shown in Patent Document 2, when casting a cast mold by pouring a molten metal of SKD61 at 1550 ° C. as a casting mold material, a low-temperature high-pressure gas is placed in the stainless pipe. By passing, the stainless steel pipe is cast without melting and does not prevent carburization or melting of the stainless steel pipe by the molten metal.

  The one shown in Patent Document 3 relates to a cooling stave of a blast furnace, and the cooling pipe has a double pipe structure composed of an inner pipe and an outer pipe, and an alumina coating is formed on the outer side of the outer pipe. Even if it occurs, its propagation can be prevented. However, since an air gap is formed between the inner pipe and the outer pipe, there is a problem that the cooling effect is lowered by the air gap.

  In Patent Document 4, a refractory first coating formed by applying a mixture of a refractory mixture as a main aggregate, and a mixture of a caking additive such as clay or water glass and water to the outside of a cooling pipe. Since the porosity of the layer is high and an effective carburizing prevention effect cannot be obtained, by forming a specific second coating layer outside the coating layer, when casting an iron-based base metal, The second coating layer softens and penetrates into the pores of the first coating layer to prevent carburization of the cooling pipe surface layer. The formation of the second coating layer as described above is indispensable and a complicated manufacturing process is required. You will need it.

  In what is shown in Patent Document 5, the adhesion between the metal tube and the refractory layer is not sufficient, and when the molten metal is cast, the refractory layer is peeled off from the metal tube by the high temperature molten metal, and carburization occurs from that portion. There is a problem that the metal pipe melts.

  In what is shown in Patent Document 6, it is necessary to quickly melt the inorganic refractory by the cast iron melt to form a glass, but depending on the portion, the molten metal permeates without rapidly becoming a glass. In that case, there is a possibility that the carbon of the molten metal carburizes into the metal tube and melts. Moreover, the adhesiveness of a metal tube and a refractory layer is inadequate, and a refractory layer may peel depending on the shape and arrangement | positioning location of a metal tube.

  The object of the present invention is to solve the above-mentioned problems, and when the temperature control steel pipe is set in a mold for casting into a cast iron mold and the molten cast iron casting is poured, the carbon in the cast iron molten steel is a steel material. It is to prevent the steel pipe from being damaged by carburizing the steel to melt the steel pipe.

In order to solve the above problems, in the present invention, various studies have been conducted on coating films that can adhere to and adhere to the outer surface of a steel pipe. As a result, when a coating film is formed on the outer surface of the steel pipe using a binder solution obtained by hydrolyzing ethyl silicate containing SiO ₂ , the hydrolyzed ethyl silicate exhibits excellent adhesiveness. It was found that it can be firmly attached to the outer surface. However, since this binder liquid has good fluidity and low viscosity, the coating film formed is thin even when applied. Therefore, it was found that the thermal shock strength and the carburization prevention function are insufficient. This was the same result even when silica sol was used as the binder liquid.

  As a result of further research after that, in the present invention, a refractory material flower such as zircon flower is mixed in the binder liquid to produce a slurry liquid, and when this slurry liquid is applied to the outer surface of the steel pipe, the film thickness of the coating film It was found that the heat-resistant impact strength was improved and the carburization prevention function was exhibited by forming a layer of this refractory flower.

Specifically, in order to achieve the above object, according to the first aspect of the present invention, there is provided a cast iron mold in which a steel pipe for temperature control is cast inside, and the steel pipe is formed on the outer surface thereof with SiO _2. To a binder solution made by hydrolyzing ethyl silicate containing 28 to 40% by mass, or a binder solution made of silica sol containing 20 to 40% by mass of SiO ₂ with respect to 1 liter of the binder solution A coating layer (coating film) is obtained by applying and drying a slurry mixed with 1.5 to 4.5 kg of refractory material flour consisting of at least one of zircon, fused silica, alumina, mullite, and chamotte. The temperature of the cast iron mold is adjusted by the fluid passed through the steel pipe.

According to a second aspect of the present invention, in the cast iron mold according to the first aspect, the refractory material flour is 200 to 350 mesh, and the thickness of the coating layer is 60 μm to less than 500 μm.

The invention of claim 3 is a cast iron mold according to claim 1 or 2, wherein a slurry layer in which the refractory material flour is mixed with the binder solution is applied twice or more to form a coating layer. is there.

According to a fourth aspect of the present invention, in the cast iron mold according to any one of the first to third aspects, at least one of zircon, fused silica, alumina, mullite, and chamotte is further formed outside the coating layer formed by the coating. refractory layer of fine grains consisting of species covered by sanding, the thickness of the coating layer combined a covering layer and the refractory layer according to the coating is configured is 200Myu～1000myu.

The invention of claim 5 is a method for producing a cast iron mold in which a steel pipe for temperature control is cast, and obtained by hydrolyzing ethyl silicate containing 20 to 40% by mass of SiO ₂ The binder liquid made of silica or the binder liquid made of silica sol containing 20 to 40% by mass of SiO ₂ has a particle size of 200 to 350 mesh and consists of at least one of zircon, fused silica, alumina, mullite, and chamotte. Refractory material flour is mixed at a ratio of 1.5 to 4.5 kg with respect to 1 liter of binder liquid to produce a slurry liquid . After the slurry liquid is applied to the steel pipe, it is naturally dried or dried by heating. , the outer surface of the steel tube by attaching the slurry to form a coating layer (coating film) on the outer surface of the steel pipe, but Guru I cast into a steel tube for temperature adjustment of forming a coating layer on the outer surface It is configured to produce a steel mold.

Invention of Claim 6 is a manufacturing method of the cast iron metal mold of Claim 5, Comprising: A particle size is 60-170 mesh, Comprising: From at least 1 sort (s) among zircon, a fused silica, an alumina, a mullite, and a chamotte. The refractory fine particles are prepared, and before the coating layer formed by the slurry liquid is dried, the refractory fine particles are adhered onto the coating layer by sanding to form a refractory layer outside the coating layer. It is the structure to do.

A seventh aspect of the invention is a method for producing a cast iron mold according to the fifth or sixth aspect, wherein the slurry liquid is applied twice or more times to form a coating layer .

  The invention of claim 8 is the method for producing a cast iron mold according to any one of claims 5 to 7, wherein the viscosity of the slurry liquid is 10 to 80 seconds at Zahn cup # 4 (50 cc). It is the composition which is.

According to the invention of claim 1, since the outer periphery of the steel pipe is covered with a coating layer (coating film) having good adhesion and excellent heat resistance, it is possible to effectively prevent carbon of the cast iron melt from carburizing into the steel pipe. At the same time, the thickness of the coating layer is thin, even for thermally conductive transmitted to heat the cast iron of the fluid in the steel tube, the coating layer has no superior effects interfering. Moreover, the slurry liquid to be applied can be dried quickly, and the outer periphery of the steel pipe can be covered with a strong coating layer having good adhesion and excellent heat resistance. Further, the slurry liquid to be applied is stable and hardly deteriorated, and the outer periphery of the steel pipe can be covered with a coating layer with good adhesion and excellent heat resistance with little variation.

According to invention of Claim 2, it is further excellent in the high temperature thermal shock property with respect to a molten metal, and can exhibit the carburization prevention effect stably. Moreover, it is excellent in the adhesiveness between the coating layer and the steel pipe, can maintain high strength adhesiveness without peeling even when a high-temperature molten metal is poured, and is excellent in a carburization preventing function.

According to invention of Claim 3, while being excellent in the adhesiveness of a coating layer and a steel pipe, the high temperature heat resistance at the time of inject | pouring a high temperature molten metal improves, and a carburization prevention function improves.

According to the invention of claim 4, a uniform coating layer can be obtained, and the thermal shock resistance to the high-temperature molten metal is excellent, the function of preventing peeling from the outer surface of the steel pipe is excellent, and the carburization prevention is also excellent . Moreover, it is possible to effectively achieve both the prevention of carburization from the cast iron melt to the steel pipe and the heat transfer of the fluid in the steel pipe to the cast iron.

According to the invention of claim 5, the coating layer (coating film) for preventing carburization of the cast iron melt can be formed on the outer periphery of the steel pipe with a thin thickness and good adhesion. In particular, the coating layer can be reliably formed on the entire outer periphery of the steel pipe. Moreover, it is the method of apply | coating a slurry liquid, and even if a pipe is bent, a coating layer can be formed easily.

According to invention of Claim 6, the coating layer excellent in the thermal shock resistance and the carburizing prevention function can be manufactured stably. Further, it can be applied partially, and the degree of freedom in selecting the coating layer is great.

According to the invention of claim 7, it is possible to form a coating layer further excellent in thermal shock.

According to the invention of claim 8, it is possible to obtain a coating layer that has excellent adhesion and effectively prevents carburization of molten carbon.

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 shows a mold for casting a temperature-adjusting steel pipe forming a heating / cooling passage into a cast iron mold. FIG. 2 shows a cross-sectional view of a temperature control steel pipe in which a coating layer is formed on the outer surface before being set in the mold.

  In order to cast a temperature-controlled steel pipe 2 processed into a predetermined shape in a cast iron mold 1 in advance, the steel pipe 2 is incorporated at a predetermined position of a self-hardening mold 3 having a cavity 4 corresponding to the cast iron mold 1, and a cast iron melt 5 is cast into the cavity 4. As a result, the cast iron mold 1 in which the steel pipe 2 for temperature control is cast is manufactured. In this embodiment, the coating layer 10 is formed on the outer periphery of the steel pipe 2 having a circular cross section. In addition, both ends of the steel pipe 2 are filled with a sealing material such as glass wool 6 for preventing the molten metal from entering.

  The coating layer 10 will be described with reference to FIG. The first layer 11 formed in close contact with the outer peripheral surface of the steel pipe 2 is obtained by applying a slurry liquid obtained by mixing a refractory material flower such as zircon flower to a binder liquid obtained by hydrolyzing ethyl silicate. Coating film. The same layer as the first layer is applied as a second layer 12 on the outside of the first layer 11.

Next, the formation method of the coating film (coating layer 10) to a steel pipe is demonstrated.

Specific gravity: 1.04 to 1.08, viscosity (25 ° C.): 2.6 to 6.0 mPa.s s, SiO ₂ ratio (mass% of silica obtained from the monomer): 38 to 43% by mass, ratio of residual acid content: ethyl silicate 40, hydrochloric acid, isopropyl alcohol included in the range of 0.01 or less, and Water is mixed to produce a binder solution obtained by hydrolyzing ethyl silicate. A slurry liquid is produced by mixing 40 kg of zircon flour having a basic particle size of 300 mesh with 10 liters of the binder liquid. A steel pipe (carbon steel for mechanical structure, C: 0.12%) is immersed in the slurry liquid thus produced and applied to the outer surface, and then pulled up from the slurry liquid. As a result, a coating film containing zircon flour is generated on the outer surface of the steel pipe. After this coating film is lightly dried, it is dipped once again in the same slurry solution and applied twice. Then air dry. In the case where it is desired to dry quickly, it may be dried by heating using a burner or the like. In this way, a 200 μm coating film was formed on the outside of the steel pipe.

  A test example in which the steel pipe is cast into a cast iron casting will be described.

Mold material: FCD450
Cast iron block: 600x400x250mm (430kg)
Pipe: φ17.3, t = 2.8mm
Casting temperature: 1350 ° C
When the cast iron casting made in this way was inspected, the steel pipe maintained its original shape without being melted, and was completely cast into a cast iron casting. For example, when the temperature adjusting fluid that has flowed into the steel pipe is cooling water, the cast iron casting can be cooled. In the case of heating hot water, the function of heating the cast iron casting can be effectively performed. It was found that it has a sufficient function.

The ethyl silicate used in the present invention has a specific gravity of 1.04 to 1.08 and a viscosity (25 ° C.) of 2.6 to 6.0 mPa.s. s, SiO ₂ ratio (silica mass% obtained from monomer): 38 to 43 mass%, residual acid ratio: 0.01 or less, for example, ethyl silicate 40 is used. As already known, ethyl silicate is hydrolyzed by adding an alcohol solvent, water and an acid catalyst. As a result, the ethyl silicate is imparted with adhesiveness, and thus has excellent adhesion when adhered to the outer periphery of the steel pipe. In addition, since the solvent is alcohol and no water-soluble solvent is used, there is no inconvenience such that moisture remains and drying takes time. In particular, if this moisture remains, it will evaporate and expand when the cast iron melt is poured, causing the problem of “killing”, but since it is treated with an alcohol-based solvent, there is no concern.

Since SiO _{2 in} ethyl silicate functions as a heat-resistant coating film, the thermal shock resistance against the molten metal can be improved. This SiO ₂ is preferably contained in the ethyl silicate in an amount of 28 to 40% by mass. In order to form a heat-resistant coating film of SiO _{2 on} the outer periphery of the steel pipe, at least 28% by mass is necessary, and when it exceeds 40% by mass, the condensation reaction proceeds excessively and becomes unstable. Since the adhesiveness deteriorates, the above range is adopted.

  A slurry liquid is produced by adding and mixing a refractory material flour composed of at least one of zircon, fused silica, alumina, mullite, and chamotte into a binder liquid obtained by hydrolyzing ethyl silicate. By adding the refractory flour, the viscosity of the binder liquid can be increased, so that the thickness of the coating film can be increased. At the same time, by having these refractory material flours in the coating film, the thermal shock resistance is improved, and the function of preventing the carbon of the cast iron melt from carburizing into the steel pipe is effectively achieved.

  In particular, since zircon has a high melting point of 2040 ° C., it is particularly effective when the cast iron melt is hot.

  The particle size of the refractory flour is preferably a fine powder of 200 to 350 mesh and a relatively narrow particle size distribution. When the fine powder particles are large, the fine powder is less likely to be uniformly distributed when applied to the outer periphery of the steel pipe, and the adhesion to the outer periphery of the steel pipe is poor. On the other hand, if the particles are too small, the binder liquid and the fine powder are difficult to mix, resulting in high costs and poor practicality. Therefore, the above range is preferable.

  The thickness of the coating film is preferably 60 μ to 500 μ, particularly preferably 100 μ to 300 μ. The thickness of the coating film is to ensure the thermal shock resistance against the high temperature molten metal when the molten metal is injected, and to prevent the carbon in the molten metal from passing through the coating film and further carburizing into the steel pipe. It is preferable that it is as thick as possible. On the other hand, the thickness of the coating film should be as thin as possible in order to transfer the temperature of the fluid in the steel pipe to the cast iron. Therefore, the thickness of the coating film is preferably in the above range. In the case where the film thickness is insufficient due to the single attachment, it is effective to make it adhere several times such as twice, three times, and the like.

  The binder liquid and the refractory flour are preferably 1.5 kg to 4.5 kg with respect to 1 liter of the binder liquid. In particular, the amount is preferably 2.0 kg to 4.0 kg. Increasing the mass of the refractory flour increases the viscosity, making it difficult to apply evenly and thinly on the outer periphery of the steel pipe. If the mass is small, only a very thin film can be formed with a low viscosity, and the temperature of the melt is high In this case, cracking is likely to occur, and the carburization prevention of the molten carbon becomes insufficient, so the above range is set.

  In particular, in order to be able to be applied to the outer surface of a steel pipe with good adhesion and to prevent carburization of molten carbon, it is important to manage the amount of the binder liquid and refractory flour in the slurry liquid, and to manage the viscosity of the slurry liquid. It is also important. When the viscosity of the slurry liquid is low, only a thin coating film can be formed, and carburization of molten carbon cannot be prevented. On the other hand, when the viscosity of the slurry liquid is high, it is difficult to apply it uniformly and thinly on the outer periphery of the steel pipe, and the adhesion with the outer periphery of the steel pipe is also poor. Therefore, it is preferable to manage the viscosity of the slurry liquid in 10 to 60 seconds with Zahn cup # 4 (50 cc). In particular, it is preferably 15 seconds to 40 seconds.

  Specifically, when the viscosity of the slurry liquid is managed by the mixing amount of the refractory material flour mixed in the binder solution, it is necessary to manage the Vol% of the refractory material flour to a predetermined amount. In that case, among refractory flours, those having a high specific gravity such as zircon have a relatively large mass to be mixed, and those having a low specific gravity such as alumina have a relatively small mass to be mixed.

Moreover, when a refractory layer is formed by sanding refractory fine particles such as zircon sand on the coating film formed by applying the slurry liquid, the coating film becomes homogeneous and the film becomes uniform. Thickness can be sufficiently secured, and high strength high temperature thermal shock resistance can be secured. The refractory fine particles have a particle size of 60 to 170 mesh, preferably 80 to 130 mesh. It is preferable that the particle size distribution is relatively narrow. In order to surely prevent the carbon of molten cast iron from carburizing into the steel pipe, it is preferable that the refractory layer is uniformly distributed, but for this purpose, the particle size is too large or too small. Is less likely to be uniformly distributed, and is preferably within the above range.

The film thickness of the coating film (coating layer) obtained by combining the coating film (coating layer) by the application and the refractory layer is preferably 200 μm to 1000 μm, particularly 300 μm to 800 μm. The film thickness of the coating film ensures thermal shock resistance to the high temperature molten metal when the molten metal is injected, and in order to prevent carbon in the molten metal from passing through the coating film and further carburizing into the steel pipe, The thickest possible one is preferable. On the other hand, in order to transfer the temperature of the fluid in the steel pipe to the cast iron, the coating film should be as thin as possible. Therefore, the total film thickness of the coating film is preferably within the above range.

  The binder liquid obtained by hydrolyzing ethyl silicate used in the present invention is subjected to a hydrolysis reaction by adding an alcohol solvent, water and an acid catalyst to ethyl silicate, and the alcohol solvent used in this case is ethyl alcohol, isopropyl alcohol, Anhydrous methyl alcohol, propylene alcohol, butyl alcohol and the like are used. The acid catalyst is hydrochloric acid or the like.

(Embodiment 2)
As Embodiment 2, after applying the slurry liquid similar to Embodiment 1 to the surface of a steel pipe only, before the coating layer dries, it is sandy refractory fine grain (zircon sand, particle size: 60-80). A refractory layer is formed by sprinkling (mesh) (this operation is called sanding or stucco). Then air dry. In the case where it is desired to dry quickly, it may be dried by heating using a burner or the like. In this way, a total coating layer of 500 μm was formed on the outside of the steel pipe.

  When the steel pipe of the second embodiment was cast into a cast iron casting as in the first embodiment, the steel pipe maintained its original shape without being melted and completely cast into cast iron. In addition, when the heat transfer between the steel pipe and the cast iron casting was tried, the temperature control fluid flowing through the steel pipe cooled the cast iron casting in the case of cooling water, for example. It has been found that the function of heating the casting can be effectively performed and the function is sufficient for heat transfer.

(Embodiment 3)
As the third embodiment, with respect to the silica sol 1-liter containing _SiO 2 30 wt%, by adding distilled 0.2 liters water, to produce a binder solution prepared of SiO ₂ to 25% by weight. A slurry liquid is produced by mixing 40 kg of zircon flour having a basic particle size of 300 mesh with 10 liters of the binder liquid. A steel pipe (carbon steel for mechanical structure, C: 0.12%) is immersed in the slurry liquid thus produced and applied to the outer surface, and then pulled up from the slurry liquid. As a result, a coating film containing zircon flour is generated on the outer surface of the steel pipe. After this coating film is lightly dried, it is dipped once again in the same slurry solution and applied twice. Then air dry. In the case where it is desired to dry quickly, it may be dried by heating using a burner or the like. In this way, a 200 μm coating film was formed on the outside of the steel pipe.

  When the steel pipe of the third embodiment was cast into a cast iron casting in the same manner as in the first embodiment, the steel pipe maintained its original shape without being melted and completely cast into a cast iron casting. For example, when the temperature adjusting fluid that has flowed into the steel pipe is cooling water, the cast iron casting can be cooled. In the case of heating hot water, the function of heating the cast iron casting can be effectively performed. It was found that it has a sufficient function.

  The silica sol (colloidal silica) used in the present invention has a silica particle size of 7 to 20 nm, a silica concentration of 20 to 40% by mass, and a viscosity (25 ° C.) of 3 to 10 mPa.s. s, specific gravity: 1.1-1.3 is used.

Since SiO ₂ in the silica sol functions as a heat-resistant coating film, the thermal shock resistance against the molten metal can be improved. This SiO ₂ is preferably contained in the binder in an amount of 20 to 40% by mass. In order to form a heat-resistant coating film of SiO _{2 on} the outer periphery of the steel pipe, at least 20% by mass is necessary, and when it exceeds 40% by mass, the adhesion with the outer periphery of the steel pipe is deteriorated, so the above range is set. .

Slurry using a binder solution of silica sol, ethyl silicate weak volatile than hydrolyzed binder liquid slurry using a strong dripping state as compared with that of the same viscosity, formation of the coating film It takes time to dry and solidify. The coating film is thinner as the viscosity is lower, and the higher the viscosity is, the thicker the film is, but the thickness is not uniform, and unevenness is likely to occur. In order to apply the slurry liquid, it is preferable to turn the steel pipe or change the inclination up and down so that the film thickness does not become uneven due to liquid dripping.

  In particular, in order to be able to apply the outer surface of a steel pipe with good adhesion and to prevent carburization of molten carbon, management of the amount of binder liquid and refractory flour in the slurry liquid is important, and viscosity control of the slurry liquid It is also important. When the viscosity of the slurry liquid is low, only a thin coating film can be formed, and carburization of molten carbon cannot be prevented. On the other hand, when the viscosity of the slurry liquid is high, it is difficult to apply it uniformly and thinly on the outer periphery of the steel pipe, and the adhesion with the outer periphery of the steel pipe is also poor. Therefore, it is preferable to manage the viscosity of the slurry liquid in 10 to 80 seconds with Zahn cup # 4 (50 cc). In particular, it is preferably 18 seconds to 65 seconds.

  Specifically, when the viscosity of the slurry liquid is managed by the mixing amount of the refractory material flour mixed in the binder solution, it is necessary to manage the Vol% of the refractory material flour to a predetermined amount. In that case, among refractory flours, those having a high specific gravity such as zircon have a relatively large mass to be mixed, and those having a low specific gravity such as alumina have a relatively small mass to be mixed.

  The particle size / mixing amount of the refractory flour, the thickness of the coating film by the flour, the particle size / thickness of the refractory fine granule coated by sanding, and the thickness of the coating film are not particularly described in Embodiment 3. For the thing, the thing of the range demonstrated in Embodiment 1 is employable, and description is abbreviate | omitted here.

(Embodiment 4)
As Embodiment 4, after applying the slurry liquid similar to Embodiment 3 to the surface of a steel pipe, before the coating layer (coating film) dries, sand-like refractory fine particles (zircon sand, The particle size: 60-80 mesh) is sprinkled to form a refractory layer (this operation is called sanding or stucco). Then air dry. In the case where it is desired to dry quickly, it may be dried by heating using a burner or the like. In this way, a total coating layer of 600 μm was formed on the outside of the steel pipe.

  When the steel pipe of this fourth embodiment was cast into a cast iron casting in the same manner as in the first embodiment, the steel pipe maintained its original shape without being melted and completely cast into cast iron. In addition, when the heat transfer between the steel pipe and the cast iron casting was tried, the temperature control fluid flowing through the steel pipe cooled the cast iron casting in the case of cooling water, for example. It has been found that the function of heating the casting can be effectively performed and the function is sufficient for heat transfer.

When the refractory fine particles are deposited on the coating film by sanding before the coating film formed by the slurry liquid is dried, the coating film is formed quickly and a uniform coating film is obtained and the coating film is thick and stable. Things are obtained.

  In addition, the following tests were conducted.

  First, a low carbon iron rod (φ8.5) was prepared. The following coating layers (1) to (5) were formed on the surface.

(1) What applied only the binder liquid which hydrolyzed the ethyl silicate This binder liquid is a binder liquid produced | generated by adding an alcohol solvent, water, and an acid catalyst to the ethyl silicate 40, and having viscosity. Was 5 seconds with Zahn Cup # 4 (50 cc), and the film thickness of the coating film was 35 μm.

(2) Application of (1) twice The viscosity was 5 seconds with Zahn Cup # 4 (50 cc), and the coating film thickness was 40 μm.

(3) The binder solution of (1) mixed with zircon flour and coated The binder solution obtained by hydrolyzing ethyl silicate 40 has a basic particle size of 350 mesh with respect to 10 liters of this binder solution. A slurry liquid is produced by mixing 35 kg of a certain zircon flour. The viscosity was 18 seconds with Zahn Cup # 4 (50 cc), and the coating film thickness was 60 μm.

(4) What applied the thing of (3) twice The viscosity was 18 seconds by Zahn cup # 4 (50 cc), and the film thickness of the coating film was 200 micrometers.

(5) Zircon Sand Fine Particles Sanded on the Outside of (3) The zircon sand has a particle size of 60 to 80 mesh and a coating layer of 500 μm in total was formed on the outside of the steel pipe.

  (6) In (3), the zircon flour was 30 kg, the viscosity was 15 seconds with Zahn cup # 4 (50 cc), and the coating film thickness was 50 μm.

  (7) In (3), the zircon flour was 40 kg, the viscosity was 30 seconds with Zahn cup # 4 (50 cc), and the coating film thickness was 150 μm. In addition, in the case of sanding fine grains of zircon sand having a particle size of 60 to 80 mesh, a coating layer of 550 μm in total was formed on the outside of the iron bar.

  (8) In (3), it was applied once using alumina flour instead of zircon flour. A slurry liquid was produced by mixing 26 kg of alumina flour having a basic particle size of 350 mesh with 10 liter of binder liquid. The viscosity was 18 seconds with Zahn Cup # 4 (50 cc), and the thickness of the coating film was 100 μm. In addition, in the case of sanding fine particles of alumina sand having a particle size of 60 to 80 mesh, a total coating layer of 380 μm was formed on the outside of the iron bar.

  (9) In (3), it was applied once using mullite flower instead of zircon flower. A slurry liquid was produced by mixing 21 kg of mullite flour having a basic particle size of 350 mesh with 10 liter of binder liquid. The viscosity was 20 seconds with Zahn Cup # 4 (50 cc), and the thickness of the coating film was 120 μm. In addition, when a mullite sand fine particle having a particle size of 60 to 80 mesh was sanded, a total coating layer of 400 μm was formed on the outside of the iron bar.

(10) one coated only binder solution consisting of silica sol This binder solution, distilled water sol containing SiO ₂ 30 wt% was added 20 wt%, a binder solution was adjusted to SiO ₂ to 25 wt% The viscosity was 5 seconds with Zahn Cup # 4 (50 cc), and the film thickness of the coating film was 35 μm.

(11) What applied (10) twice The viscosity was 5 second by Zahn cup # 4 (50 cc), and the film thickness of the coating film was 40 micrometers.

(12) Zircon flower mixed with the binder liquid of (10) and coated 35 g of zircon flower whose basic particle size is 350 mesh with respect to 10 liter of this binder liquid. To produce a slurry liquid. The viscosity was 34 seconds with Zahn Cup # 4 (50 cc), and the thickness of the coating film was 150 μm.

(13) The product of (12) applied twice The viscosity was 34 seconds with Zahn Cup # 4 (50 cc), and the film thickness of the coating film was 230 μm.

(14) Sanding fine grains of zircon sand on the outside of (12) The grain size of this zircon sand was 60-80 mesh, and a coating layer of 500 μm in total was formed on the outside of the iron bar.

  (15) In (12), the zircon flour was 30 kg, the viscosity was 18 seconds with Zahn cup # 4 (50 cc), and the coating film thickness was 100 μm.

  (16) In (12), the zircon flour was 40 kg, the viscosity was 65 seconds with Zahn Cup # 4 (50 cc), and the coating film thickness was 200 μm. In addition, in this case, in the case of sanding fine grains of zircon sand having a particle size of 60 to 80 mesh, a coating layer of a total of 600 μm was formed on the outside of the iron bar.

  (17) In (12), alumina flour was used instead of zircon flour and applied once. A slurry liquid was produced by mixing 26 kg of alumina flour having a basic particle size of 350 mesh with 10 liter of binder liquid. The viscosity was 20 seconds with Zahn Cup # 4 (50 cc), and the film thickness of the coating film was 150 μm. In addition, in the case of sanding fine particles of alumina sand having a particle size of 60 to 80 mesh, a coating layer having a total thickness of 400 μm was formed on the outside of the iron bar.

  (18) In (12), it was applied once using mullite flower instead of zircon flower. A slurry liquid was produced by mixing 21 kg of mullite flour having a basic particle size of 350 mesh with 10 liter of binder liquid. The viscosity was 22 seconds with Zahn Cup # 4 (50 cc), and the thickness of the coating film was 200 μm. In addition, a mullite sand fine particle having a particle size of 60 to 80 mesh was sanded, and a total coating layer of 450 μm was formed on the outside of the iron bar.

  On the other hand, as a cast iron melt, a FCD450 original bath, that is, a CE value of 4.23 (C: 3.71, Si: 1.46) and a melt temperature of 1370 ° C. was prepared.

  The iron bars (1) to (18) were soaked in the molten metal for about 30 seconds.

As a result, in (1), (2), (10), and (11), almost no coating film remained and the diameter of the iron rod was melted down to half or less. This is because the carbon of the molten metal carburized into the iron rod through the coating film and melted the iron rod, and there was no carburizing prevention effect of the coating film.

  On the other hand, in all of (3) to (9) and (12) to (18), the coating layer remained, and the iron bar remained in its original diameter. This is because the coating layers (3) to (9) and (12) to (18) were able to withstand the thermal shock of the molten metal and remained firmly attached to the outer surface of the iron bar, and the molten carbon. It shows that carburization was effectively prevented.

(Other embodiments)
In the present invention, the coating film by coating may be repeatedly applied several times, or the coating film by coating and the refractory layer may be alternately stacked.

  Further, the refractory layer may be coated on the entire circumference of the coating film by coating, or may be partially used particularly in a portion where heat resistance strength is required.

  The cast iron is ordinary cast iron, spheroidal graphite cast iron or the like. The steel pipe is low carbon steel, stainless steel, high temperature steel pipe or the like.

  In the above embodiment, the method of applying the slurry liquid to the surface of the steel pipe is a method of immersing the steel pipe in the slurry liquid. However, the method is not limited to this method, and other application methods may be used. For example, it includes drawing the slurry liquid into a basket and pouring it on, or applying it by brushing. In particular, in the case of a steel pipe with a shape such as a bend, a long steel pipe, etc., the slurry liquid tank becomes large in the method of immersing the steel pipe in the slurry liquid tank. The application method is practical. In addition, brushing is effective when partially applied.

In addition, the refractory fine particles coated on the outer surface of the coating film (coating layer) can be sprinkled on the outer surface of the steel pipe on which the coating film is formed or the refractory fine particles are dispersed on the sheet, Various coating methods can be used, such as placing on a refractory fine grain and coating the surrounding refractory fine grain on a steel pipe or rolling and coating the steel pipe, spraying with a spray member, dropping from a dropping member, etc. is there.

  The temperature control of the temperature control steel pipe includes a case where the steel pipe is used as a cooling steel pipe for cooling the casting with a refrigerant in the steel pipe, and a case where the steel pipe is used as a heating steel pipe for heating the casting with a heating fluid in the steel pipe.

  The present technology can be applied to a cast iron product in which a temperature control steel pipe is cast, such as a cooling stave of a metallurgical furnace such as a blast furnace or a mold for a resin molding machine.

In this invention, it is sectional drawing which shows the casting_mold | template structure which casts the cast iron metal mold | die which casts the steel pipe which forms the channel | path for heating and cooling. In this invention, sectional drawing of the steel pipe which formed the coating film in the outer surface is shown.

DESCRIPTION OF SYMBOLS 1 Cast iron metal mold 2 Steel pipe 3 Mold 10 Covering layer 11 1st layer 12 2nd layer

Claims (8)

A cast iron mold in which a steel pipe for temperature control is cast inside,
In the steel pipe outer surface thereof, the binder solution consisting of those ethyl silicate containing SiO ₂ 28 to 40% by weight obtained by hydrolyzing or binder solution comprising a SiO ₂ silica sol containing 20 to 40 wt% To 1 liter of the binder solution, a slurry solution in which 1.5 to 4.5 kg of a refractory material flour composed of at least one of zircon, fused silica, alumina, mullite, and chamotte is mixed is applied and A cast iron mold, wherein the cast iron mold is formed by drying to form a coating layer, and the temperature of the cast iron mold is controlled by a fluid passed through the steel pipe. The cast iron mold according to claim 1,
The refractory flower is 200-350 mesh,
A cast iron mold, wherein the coating layer has a thickness of 60 μm to 500 μm. In the cast iron mold according to claim 1 or 2,
A cast iron mold, wherein a coating layer is formed by applying a slurry liquid in which the refractory flour is mixed with the binder liquid two or more times. In the cast iron mold according to any one of claims 1 to 3,
A fine refractory layer composed of at least one of zircon, fused silica, alumina, mullite, and chamotte is further coated by sanding on the outer side of the coating layer by the above application,
A cast iron mold, wherein the coating layer formed by the coating and the refractory layer has a thickness of 200 μm to 1000 μm. A method for producing a cast iron mold in which a steel pipe for temperature control is cast,
Binder solution comprising ethyl silicate containing SiO ₂ 28 to 40 wt% those obtained by hydrolyzing, or SiO ₂ in the binder solution consisting of silica sol containing 20 to 40 wt%, zircon, fused silica, alumina , Mullite, chamotte, and a slurry liquid in which 1.5 to 4.5 kg of refractory flour with a particle size of 200 to 350 mesh is mixed with 1 liter of the binder liquid. And
After applying the slurry liquid to the steel pipe, it is naturally dried or heat-dried, the slurry liquid is attached to the outer surface of the steel pipe to form a coating layer on the outer surface of the steel pipe,
A method for producing a cast iron mold, comprising producing a cast iron mold in which the temperature-adjusting steel pipe having a coating layer formed on an outer surface is cast inside. In the manufacturing method of the cast iron metal mold according to claim 5,
The particle size is 60-170 mesh, and refractory fine particles comprising at least one of zircon, fused silica, alumina, mullite, chamotte are prepared,
Before the coating layer formed by the slurry liquid is dried, the refractory fine particles are adhered onto the coating layer by sanding to form a refractory layer outside the coating layer . Mold manufacturing method. In the manufacturing method of the cast iron metal mold according to claim 5 or 6,
A method for producing a cast iron mold, wherein the slurry liquid is applied two or more times to form a coating layer . In the manufacturing method of the cast iron metal mold | die as described in any one of Claim 5 thru | or 7,
A method for producing a cast iron mold, wherein the viscosity of the slurry liquid is 10 to 80 seconds with Zahn cup # 4 (50 cc).

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