JP2007090384A - Molding method of self-hardening-mold using lost pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method of a self-hardening-mold using a lost pattern, which has both of convenience of the molding method of a self-hardening-mold and certainty of formation of a mold cavity in a mold. <P>SOLUTION: An integrated mold composed of a pattern and a mold is prepared in such a way that a lost pattern consisting of urea composition is buried in a self-hardening-mold that does not collapse in boiling water. The lost pattern is eluted and removed by immersing the integrated mold in boiling water for 10-50 minutes. The mold, in which a mold cavity is formed, is taken out from the boiling water, dried with heat for 3-8 hours, so that the self-hardening-mold is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a self-hardening mold making method using a urea composition as a disappearance model.

  As a typical disappearance model casting method, a method using a ceramic shell mold represented by an investment precision casting method and a full mold casting method using a self-hardening mold are known.

  The investment casting method uses a vanishing model made of wax, synthetic resin foam, urea resin, and other thermally decomposable materials, and the mold is made of ceramic slurry in which a refractory material is mixed with a binder. By molding and firing the mold, the disappeared model is incinerated and removed, and a ceramic shell mold having a cast cavity is formed. This mold is made of strong refractory ceramic, and the casting cavity has a shape that faithfully transfers the disappearance model, and is excellent in castability, so it is known to be widely used in precision casting.

  As an example of this investment precision casting method, the disappearance model is made of a soluble material such as urea resin, and this model is repeatedly dipped in the refractory material slurry of the mold material, and then pulled up and dried repeatedly on both the inside and outside of the model. It is possible to produce a hollow ceramic mold by melting and removing the model sandwiched between the refractory material layers when firing the refractory material layer after the attached refractory material layer reaches the required thickness. Known (for example, Patent Document 1).

  The wax model is immersed in a slurry containing sodium silicate or potassium silicate or a mixture thereof as a binder, and this is pulled up from the slurry and sanded to form a thin shell mold layer. It is known that a mold layer is rapidly cured by reacting, and this process is repeated several times to produce a ceramic mold (for example, Patent Document 2).

  The vanishing model is made of foamed polystyrene, polymethylmethacrylate, and a copolymer of both, and the vanishing model with the ceramic substrate applied to the outer periphery is heated in a heating furnace to vaporize the vanishing model and internalize the ceramic substrate. It is known that a ceramic mold is formed by firing the ceramic substrate and firing the ceramic substrate (for example, Patent Document 3).

  The wax model contained in the investment precision casting mold is directly heated by a burner, etc., and the mold material is collected by sequentially liquefying and flowing out the sprue part, runner part and product part. Was melted in hot water to melt the remaining brazing component, and the brazing component that floated on the surface of the molten metal was recovered, and these dewaxed molds were placed in a firing furnace to burn and remove the brazing component. It is known to make a ceramic mold (for example, Patent Document 4).

  The investment casting method as described above is generally superior in obtaining a precise cast product, but the application range is limited in that the molding process of the mold is complicated and special equipment is required.

  In contrast to the investment casting method described above, the full mold casting method, which is one of the casting methods using the disappearance model, uses an organic self-hardening binder such as a self-hardening furan resin for the disappearance model made of synthetic resin foam. This is a self-hardening mold embedded in the foundry sand used, and the disappeared model is pyrolyzed by the molten metal cast into the mold and replaced with molten metal to obtain the desired cast product, compared to the investment casting method. It is known as a simple and easy casting method. However, in this full mold casting method, various casting defects may occur due to the combustion gas and residue generated by the thermal decomposition of the synthetic resin foam. In order to solve this problem, the disappearance model in the mold before casting the molten metal There are known methods such as dissolving and removing the solvent with a solvent, and removing the vanished model by burning, but the workability is poor and sufficient effects have not been obtained, and various research and development have been conducted.

  For example, as a technique for solving the above-mentioned problem and erasing the synthetic resin foam from the self-hardening mold, in the disappearance model casting method in which the disappearance model made of the synthetic resin foam is embedded in the foundry sand and cast, the synthetic resin foam It is known that a solvent that dissolves is added to and mixed with foundry sand to form a gap between the disappearance model and the mold, and the burnt model is cast without being extracted (for example, Patent Document 5).

  In order to prevent the casting sand from adhering to the foamed polystyrene model and improve the mold cutting workability, phenol resin, polyisocyanate compound, fatty acid carboxylic acid ester are mixed in the binder kneaded into the molding sand of the self-hardening mold that embeds the model It is known to use an organic solvent containing as a main component (for example, Patent Document 6).

In order to improve the strength of the disappearance model in the normal full mold casting method, defects that occur during casting, etc., part or all of the disappearance model made of foam resin is formed with high density, and the molding sand is impregnated with an oxidizer in advance. It is known to mold a casting mold (for example, Patent Document 7).
Japanese Patent Publication No. 08-018754 JP2003-080345A JP2003-340546 JP 2004-268129 A JP 2000-271701 A Japanese Patent Laid-Open No. 2004-017085 JP 2004-188479 A

  In Patent Document 1, the disappearance model is made of a soluble material such as urea resin, and a shell-like mold of the refractory layer is generated on the surface of the disappearance model by immersion in the refractory material slurry and sanding. When the material is fired to form a ceramic mold, the disappearance model is melted and removed, and the molding process of the mold is complicated and special equipment is required, and it cannot be applied to the molding of a simple self-hardening mold.

  The one shown in Patent Document 2 is a wax model where the disappearance model is sanded using a water-soluble slurry binder such as sodium silicate, and the shell mold layer generated on the model surface is rapidly cured with carbon dioxide gas Therefore, it requires a complicated process and special equipment similar to the mold making using the ordinary investment casting method, and cannot be applied to simple self-hardening mold making.

  As shown in Patent Document 3, the disappearance model is a foamed material such as expanded polystyrene, and a ceramic base material is applied to the outer periphery of the disappearance model, and the ceramic base material that is vaporized and discharged from the disappearance model in a heating furnace is fired. Thus, the mold making process requires a complicated process and special equipment as in the ordinary investment casting method, and cannot be applied to a simple self-hardening mold.

  In Patent Document 4, the disappearance model is a wax model, and the wax model is liquefied and discharged without burning from the mold made according to the molding process of a normal investment precision casting mold. A method of directly heating the wax model with a flame of a burner or torch lamp, followed by a method of immersing the mold in hot water and melting the remaining wax components, complete dewaxing is done by firing the mold Achieved. This mold making method is related to ceramic shell mold making that requires a complicated process, and cannot be applied to simple self-hardening mold making.

  In Patent Document 5, the disappearance model is a synthetic resin foam, and the molten metal is cast with the disappearance model embedded in the mold, and there is a problem caused by the thermal decomposition of the disappearance model in the mold. You can't be ridiculous.

  The model shown in Patent Document 6 is a model made of polystyrene foam, and this model is extracted from the mold and used repeatedly. Unlike the mold making method, which is embedded in the mold as the disappearing model, the effect is I can't expect it.

  As shown in Patent Document 7, the disappearance model is a high-density foam, and the disappearance model is completely burned by the oxidant impregnated in the molding sand constituting the mold, but the molten metal was cast. Sometimes, the harmful effect of the disappearance model thermally decomposing in the mold is inevitable.

  The present invention makes use of the convenience of mold making in the self-hardening mold making method using the disappearance model and removes the disappearance model embedded in the self-hardening mold before casting the molten metal, thereby forming the casting cavity of the investment precision casting mold. This was obtained as a result of various studies focusing on whether certainty could be utilized in the self-hardening mold making method. It is selected from materials well-known as disappearance model materials for investment casting, by using as a disappearance model a urea composition containing a urea-based polyvinyl alcohol and a small amount of a dispersion regulator. It was strong and rigid, was able to withstand the compaction of foundry sand when making a normal self-hardening mold, and was able to remove the disappeared model embedded in the self-hardening mold using water solubility. Furthermore, it was found that the disappearance model can be removed quickly and surely by immersing the mold in which the disappearance model is embedded in boiling water, and that a self-hardening mold that does not collapse in hot water is necessary.

  In order to achieve the above-mentioned object, the invention of claim 1 is based on the fact that a disappearance model composed of a urea composition containing urea as a main component and blended with a polyvinyl alcohol and a small amount of a dispersion regulator is not dissolved in hot water. The model consists of a model mold embedded in a rigid mold, immersed in boiling boiling water, held until the disappeared model is eluted from the self-hardening mold, and the self-hardening mold is removed from the boiling water and dried. It is.

  The invention of claim 2 is a self-hardening mold making method using the disappearance model according to claim 1, wherein the self-hardening mold taken out from the boiling water is immersed and washed in boiled clean boiling water. .

  A third aspect of the invention is a self-hardening mold making method using the disappearance model according to the first or second aspect, wherein a small amount of a surfactant is added to the boiled boiling water.

  According to a fourth aspect of the present invention, there is provided a self-hardening mold making method using the disappearance model according to any one of the first to third aspects, wherein the model mold-integrated mold is immersed in boiling water in an autoclave. This is a configuration that performs auxiliary elution of the disappearance model.

  The invention according to claim 5 is the self-hardening mold making method using the disappearance model according to any one of claims 1 to 4, wherein the urea composition is 95 to 85% by weight of urea and 3 to 6 polyvinyl alcohol. The composition is composed of a mixture of 2 to 9% by weight of a dispersion adjusting agent composed of, for example, wt%, stearic acid, paraffin and water.

  The invention according to claim 6 is the self-hardening mold making method using the disappearance model according to any one of claims 1 to 5, wherein the binder of the self-hardening mold that does not disintegrate with hot water is furan self-hardening. It is the structure which consists of resin, phenol urethane self-hardening resin, phenol acid hardening self-hardening resin, alkali phenol self-hardening resin.

  The invention according to claim 7 is the self-hardening mold making method using the disappearance model according to any one of claims 1 to 6, wherein the model mold-integrated mold has the disappearance model embedded in the self-hardening mold. It is the structure formed as a child mold.

  The invention according to claim 8 is the self-hardening mold making method using the disappearance model according to any one of claims 1 to 7, wherein the disappearance model is composed of a collection of disappearance model segments having the same size and shape. It has a configuration.

  According to the invention of claim 1, by making the disappearance model with the urea composition, it becomes strong and rigid, and it can sufficiently withstand without deformation due to compaction of the foundry sand when making a normal self-hardening mold. Can do. By embedding the disappearance model in a self-hardening mold and immersing the model mold-integrated mold in boiling water, the water-soluble disappearance model is easily eluted and removed from the self-hardening mold. When boiling water is used, elution of the disappearance model is accelerated by convection of boiling water, and the cleaning action of the mold cavity from which the disappearance model has been removed is improved. Moreover, the convenience of the self-hardening mold making method is not lost by selectively using a self-hardening mold that does not break down with hot water. By combining the above elemental technologies, the production efficiency of the self-hardening mold making method using the disappearance model can be increased.

  According to the invention of claim 2, the elution removal of the disappearing model made of the urea composition becomes more reliable, and the urea composition that permeates and remains inside the mold can be reduced.

  According to the invention of claim 3, it is possible to accelerate the elution and removal of the disappearing model made of the urea composition, and to reduce the urea composition that permeates and remains inside the mold.

  According to the invention of claim 4, the time for elution and removal of the disappearance model made of the urea composition can be greatly shortened.

  According to the invention of claim 5, the disappearance model can be made strong and rigid, and the preservation property and water solubility in the air can be made appropriate.

  According to the invention of claim 6, it is possible to select from commonly used self-hardening molds, and the convenience of the self-hardening mold making method can be utilized.

  According to the invention of claim 7, the convenience and productivity of the self-hardening mold making method using the disappearance model can be improved.

  According to the invention of claim 8, the self-hardening mold in which the cast cavity formed by eluting and removing the disappearance model is formed can improve the accuracy and increase the production efficiency.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows an overall configuration of a self-hardening mold using a disappearance model according to Embodiment 1 of the present invention. 1 is a lower mold, 2 is an upper mold, 3 is a core mold fitted into the lower mold, 4 is a casting cavity in which the disappeared model formed in the core mold is eluted and removed, and 5 is a casting formed in the lower mold A cavity 6 is a casting cavity formed in the upper mold. The casting cavities 4, 5, and 6 form casting cavities corresponding to castings. 7 is a gate provided in the upper mold.

  FIG. 2 shows a schematic shape of a casting 8 produced by pouring molten metal into the casting cavities 4, 5, and 6 of the self-hardening mold having the above-described configuration. 9 is a blade part of a cast product, and is composed of 8 sheets.

  FIG. 3 shows a plan view of the vanishing model segment assembly 10 constituting the blade portion 9 of the casting 8. Reference numeral 11 denotes a vanishing model segment formed of a urea composition, and the tip portion 11a has the same shape formed in a substantially triangular prism shape. The vane portion 11b is arranged radially around the tip portion 11a of these segments 11, and the eight segments 11 are assembled to form the vanishing model assembly 10.

  FIG. 4 shows a model core mold integrated type 3 a in which the above disappearance model segment assembly 10 is embedded in a self-hardening core mold 3.

  In the first embodiment, a self-hardening core mold is formed by applying the self-hardening mold making method using the disappearance model to the forming of the core mold, and the lower mold and the upper mold, which are normal self-hardening molds, are formed. The mold making method to be assembled and used together is shown. Details of the mold casting method of the first embodiment will be described with reference to the drawings.

  The blade part 9 of the cast product 8 to be cast has the same size and shape, and is composed of eight sheets. First, the vanishing model segment 11 corresponding to the blade portion 9 is molded using a simple mold using a urea composition by a molding method similar to the vanishing model used in the investment casting method. In this case, a large number of erasure model segments 11 having the same size and shape can be used, which is advantageous. In addition, the quality of the final casting is stable and good.

  Eight vanishing model segments 11 made in the same manner are assembled as shown in FIG. Next, as shown in FIG. 4, a model core mold integrated type 3a in which the vanishing model segment assembly 10 is embedded in the self-hardening core mold 3 is manufactured. In this case, the self-hardening foundry sand is hardened in the same manner as a normal full mold molding method. Since the vanishing model segment 11 made of the urea composition of Embodiment 1 is strong and rigid, it does not break or deform even if it is strongly crushed.

  Next, the model core mold integrated type 3a is immersed in boiling water. This boiling water is boiling water that is heated and heated to about 100 ° C. so that the water is in a boiled state and is in a flowing state, and is violently convectioned and boiled. . The disappearance model embedded in the mold begins to melt in the hot water from the exposed portions of the upper and lower surfaces of the mold, and the disappearance model composed of the urea composition is eluted and removed from the self-hardening core mold by boiling water in a short time. In the case where there is no exposed portion of the disappeared model on one of the upper and lower surfaces of the mold, a temporary hole is provided in the mold to help elution removal, and this hole is closed later with the mold material.

  Although the elution removal time of the disappearance model 10 depends on the shape and size of the disappearance model, it takes 10 to 50 minutes. If the time is too short, the disappearance model will not be sufficiently eluted and removed. If the time is too long, the corners on the inner surface of the casting cavity may be damaged, resulting in energy loss. It is preferable that the time is within the above time.

  The self-hardening core mold taken out from the boiled boiling water is dried at a temperature of 150 ° C. to 170 ° C. for 3 hours to 8 hours in a drying furnace in order to eliminate moisture remaining in the mold structure. If the drying time is too short, the drainage of water is insufficient, and if it is too long, the economy is inferior.

  The self-hardening core mold manufactured in this way is set between the lower mold 1 and the upper mold 2 as shown in FIG. 1, and cast cavities 4, 5, and 6 corresponding to the cast product 8 are formed. Construct a mold. In this case, the lower mold 1 and the upper mold 2 are self-hardening molds in which the casting cavities 5 and 6 and the gate 7 are formed by a usual method. Thus, molten metal is poured into this mold to produce a casting 8.

(Embodiment 2)
Embodiment 2 will be described. Only the differences from the first embodiment will be described, and the description of the same portions will be omitted. After taking out the self-hardening core mold 3 from the boiling water boiled in the same manner as in the first embodiment, in the second embodiment, the self-hardening core mold 3 is briefly added to the boiled clean boiling water prepared separately. (5-10 minutes) soaked. Thus, the urea composition that penetrates and remains in the outer surface of the self-hardening core mold 3, the inner surface of the casting cavity, and the mold structure can be removed more completely.

  When a small amount of surfactant, for example, neutral type sodium alkyl ether sulfate, polyoxyethylene alkyl ether, fatty acid alkanolamide, or the like is added to the boiling boiling water of Embodiments 1 and 2, elution removal of disappearance model is accelerated. In addition, the urea composition eluted in the boiling water can be prevented from remaining on the inner and outer surfaces of the self-hardening core mold. The amount of surfactant added is about 0.5 milliliters per liter of water.

(Embodiment 3)
A third embodiment will be described. Only the differences from the first embodiment will be described, and the description of the same portions will be omitted. In the third embodiment, before the model core mold integrated type 3a in the first embodiment is immersed in the boiling water, the disappearance model made of the urea composition is removed by auxiliary elution using an autoclave. Autoclave uses superheated steam at 140 to 170 ° C, which is commonly used for dewaxing in the investment casting method, and can be used for auxiliary elution of disappearance models without breaking the self-hardening core mold in a short time of about 10 to 25 minutes. . The self-hardening core mold taken out from the autoclave is immersed in boiling water as in the first embodiment. In this case, the time required is about 5 to 10 minutes, and the urea component adhering to the inner and outer surfaces of the mold can be effectively removed.

  The components of the composition for making the disappearance model used in the present invention and the mixing ratio thereof will be described. The characteristics required for the disappearance model include the rigidity and strength that does not cause deformation and breakage due to the compaction of the foundry sand when making a self-hardening core mold with the disappearance model embedded, and when the dissolution model is dissolved in boiling boiling water. It is necessary to have good solubility, good formability when the disappearing model is formed using a mold, good preservability after forming, and the like. Such properties are determined by the mixing ratio of the main component urea and polyvinyl alcohol of the urea composition, and additional properties are imparted to the mixed composition by the small amount of the dispersion modifier added. The In the present invention, the urea can be used in the range of 95 to 85% by weight and the polyvinyl alcohol in the range of 3 to 6% by weight. As the proportion of alcohol increases, the strength of the molded disappearance model increases, and an appropriate blending proportion is selected according to usage requirements.

  As the dispersion adjusting agent, stearic acid, paraffin, water, and the like are used at an appropriate ratio in order to impart a uniform mixing property of the urea composition and compatibility with the intended use. This dispersion regulator is used at 2 to 9% by weight.

Example 1
As Example 1, a disappearing model shown in FIG. 2 was formed with a composition comprising 90% by weight of urea, 4.5% by weight of polyvinyl alcohol, 2% by weight of stearic acid, 1% by weight of paraffin, and 2.5% by weight of water. The self-hardening core mold 3 that does not disintegrate with hot water is a normal full mold using self-hardening furan sand containing 35% silica sand and 0.8% by weight furan resin and 0.4% by weight sulfonic acid as a binder. By the same compaction as the casting method or the normal mold making method, it was formed as the model core mold integrated type 3a shown in FIG. 4 in which the disappearance model made of the urea composition was embedded. This product is immersed in boiling water at 100 ° C. for 45 minutes according to the manufacturing process of Embodiment 1, and further immersed in clean 100 ° C. boiling water for 7 minutes to elute and remove the disappeared model, and then taken out and a drying furnace is removed. It was dried at a temperature of 170 ° C. for 5 hours and produced as a self-hardening core mold 3 in which a casting cavity was formed.

  As Example 2, a disappearance model made of the same urea composition as in Example 1 was embedded in the same self-hardening mold as in Example 1 to form a model core mold integrated type 3a. This model core mold integrated type 3a was treated with superheated steam at 170 ° C. for 15 minutes in an autoclave, then immersed in boiling water at 100 ° C. for 7 minutes, and dried at a temperature of 170 ° C. for 5 hours. As Example 3, after treating with superheated steam in the same manner as Example 2, it was immersed in boiling water, then further immersed in clean boiling water, and then dried and dried. The superheated steam was immersed in boiling water at 150 ° C. for 20 minutes and 5 minutes in 100 ° C. boiling water, then immersed in clean boiling water 100 ° C. for 5 minutes, and then dried at a temperature of 170 ° C. for 3 hours. As Example 4, a solution obtained by adding 0.5 ml of neutral type alkyl ether sodium sulfate to 1 liter of water as a surfactant in boiling water in Example 1 was used.

  As Examples 5 and 6, those in which the mixing ratio of the urea composition of Example 1 was changed were used. Example 5 contains 88% by weight of urea, 5.5% by weight of polyvinyl alcohol, 2% by weight of stearic acid, 2% by weight of paraffin, 2.5% by weight of water, and 0.3 ml of surfactant as 1 liter of water. Sex type sodium alkyl ether sulfate was added, and Example 6 used 93% by weight of urea, 3.5% by weight of polyvinyl alcohol, 1% by weight of stearic acid, 1% by weight of paraffin, and 1.5% by weight of water.

  As Comparative Example 1, the same disappearance model as that of Embodiment 1 was prepared, treated with hot hot water of 90 ° C. for 2 hours, and further treated with clean hot hot water of 90 ° C. for 1 hour. This hot water of 90 ° C. is high-temperature heated water that is not boiling. In Comparative Example 2, the same disappearance model as that of Embodiment 1 was prepared, treated with boiling water at 100 ° C. for 1.5 hours, further treated with boiling water at 100 ° C. for 7 minutes, and dried at a temperature of 170 ° C. for 5 hours. In Comparative Example 3, a disappearance model was formed with 93% by weight of urea, 35% by weight of polyvinyl alcohol, 1% by weight of stearic acid, 1% of paraffin, and 1.5% by weight of water, and treated with boiling water at 100 ° C. for 15 minutes. Further, it was treated with boiling water at 100 ° C. for 5 minutes and dried at a temperature of 170 ° C. for 5 hours.

  Table 1 shows the results of observing the discharge state of the disappearance model and the state of the mold for Examples 1 to 6 and Comparative Examples 1 to 3.

  In Examples 1 to 6, the disappeared model was discharged neatly, and the shape of the self-hardening mold could be maintained without collapsing. In contrast, in Comparative Example 1, it was treated by immersing it in hot non-boiling 90 ° C hot water for 2 hours, and further immersed in clean hot water at 90 ° C for 1 hour. It remained in the mold cavity and could not be discharged. In Comparative Example 2, the treatment time with boiling water was too long, and the inner surface of the mold cavity was rough and some defects were generated at the corners. In Comparative Example 3, an attempt was made to shorten the elution time by increasing the amount of urea in the urea composition excellent in water solubility, but the disappearance model could not be discharged sufficiently.

  For the self-hardening core mold, phenol urethane self-hardening resin, phenolic acid-hardening self-hardening resin, alkali phenol self-hardening resin, etc. are selected and used as the binder for foundry sand, in addition to furan self-hardening resin. It is possible to mold a core mold that does not.

  In the above-described embodiment, the case where the self-hardening mold making method using the disappearance model is applied to the core mold is described. Similarly, this technique is replaced with the core mold, and either the upper mold or the lower mold or By applying directly to both, a self-hardening mold in which a casting cavity is formed can be formed.

  FIG. 5 shows an impeller of a Francis turbine, and FIG. 6 shows an impeller of a centrifugal pump, as another specific example of a cast product that can be cast by applying the mold making method of the present invention. Each of them has a structure having a large number of blades of the same size and shape, and a mold for casting these can be efficiently manufactured by the mold making method of the present invention.

  The present invention makes it possible to widely apply the self-hardening mold making method using the disappearance model to core molds and mold body molding, and as cast products cast using these molds, Francis turbines Especially suitable are an impeller of a centrifugal pump, an impeller of a centrifugal pump, an impeller of a blower, a nozzle ring of a turbine, and the like.

It is the whole block diagram of the mold which assembled the self-hardening core mold which does not collapse with hot water, and formed the casting cavity. FIG. 2 is a schematic view of a cast product cast using the mold of FIG. FIG. 3 is a plan view of a vanishing model segment assembly that constitutes a blade portion of the cast product of FIG. 2. FIG. 4 is a perspective view of a model core mold integrated type in which the vanishing model segment assembly of FIG. 3 is embedded in a self-hardening core mold. It is a perspective view of the impeller of a Francis turbine to which the present invention is applied. It is a perspective view of the impeller of the centrifugal pump to which the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower mold 2 Upper mold 3 Core mold 3a Model core mold integral type 4 Casting cavity 5 formed in core mold Casting cavity 6 formed in lower mold Casting cavity 7 formed in upper mold Upper part Spout 8 provided in the mold Cast product 9 Cast blade 10 Disappearance model segment assembly 11 Disappearance model segment

Claims (8)

  Created a model mold integrated type in which the disappearance model consisting of urea composition composed mainly of urea, blended with polyvinyl alcohol and a small amount of dispersion regulator, is embedded in a self-hardening mold that does not disintegrate with hot water. A self-hardening mold making method using a disappearance model, which is immersed in boiling water and held until the disappearance model elutes from the self-hardening mold, and the self-hardening mold is removed from the boiling water and dried. In the self-hardening mold making method using the disappearance model according to claim 1,
A self-hardening mold making method using a disappearing model, characterized in that a self-hardening mold taken out from boiling water is immersed and washed in boiled clean boiling water. In the self-hardening mold making method using the disappearance model according to claim 1 or 2,
A self-hardening mold making method using a disappearance model, characterized by adding a small amount of a surfactant to boiling boiling water. In the self-hardening mold making method using the disappearance model according to any one of claims 1 to 3,
A self-hardening mold making method using a disappearing model, characterized in that the disappearing model is auxiliary eluted in an autoclave before immersing the model casting mold in boiling water. In the self-hardening mold making method using the disappearance model according to any one of claims 1 to 4,
Disappearance model characterized in that the urea composition is a mixture of 95 to 85% by weight of urea and 3 to 6% by weight of polyvinyl alcohol, 2 to 9% by weight of a dispersion control agent comprising stearic acid, paraffin, water, etc. Self-hardening mold making method using In the self-hardening mold making method using the disappearance model according to any one of claims 1 to 5,
The self-hardening mold binder that does not disintegrate in hot water is a furan self-hardening resin, a phenol urethane self-hardening resin, a phenolic acid hardening self-hardening resin, or an alkali phenol self-hardening resin. Hard mold making method. In the self-hardening mold making method using the disappearance model according to any one of claims 1 to 6,
A self-hardening mold making method using an disappearance model, wherein the model mold-integrated mold is formed as a core mold in which the disappearance model is embedded in the self-hardening mold. In the self-hardening mold making method using the disappearance model according to any one of claims 1 to 7,
A self-hardening mold making method using an disappearance model, wherein the disappearance model is composed of an assembly of disappearance model segments having the same size and shape.

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