KR800000074B1 - Mould making method - Google Patents

Abstract

A soln. (hydrophilic org. solvents or their mixt., silica sol. of<=pH6, org. binders, gelling agent) and powd. heat-resistant material are mixed to prep. slurry A; another soln. (hydrophilic org. solvents or their mixt., silica sol. of>=pH7, org. binders, gelling agent) and powd. heat-resistant material are mixed to prep. slurry B. A mold pattern is dipped in the slurry A, sanded with powd. heat-resistant material, dipped in the slurry B and coated with a powd. heat-resistant material. The process is repeated.

Description

How to make a mold

The present invention relates to a method of making a mold by accumulating refractory materials in a prototype.

Conventionally, as a method for producing a mold, a prototype is immersed in a slurry containing a powder made of a refractory material and a binder such as sodium silicate, clad silica, and ethyl silicate, and then sanded with a powder made of a refractory material ( The method of making a thick shell is carried out by repeating this process 6 to 10 times in total by repeating this process.蜜蠟) It takes 3 to 4 days until it takes a long time. In order to shorten the time required, a method of accelerating the condensation by producing a gel by a chemical method of condensing the slurry by drying has been proposed, but has a disadvantage of low mechanical strength.

In order to solve these drawbacks, a so-called rapid casting method has been proposed, which has a function of gelling other slurries to shorten the time required for coating by alternately depositing two slurries containing a refractory and a binder. One of these methods is the method described in Japanese Patent Publication No. 45-41505. This method involves sanding a slurry of ethyl silicate hydrolyzate and refractory powder, and a slurry of aqueous sodium silicate solution containing ammonia or amine and a slurry of refractory powder. It is a method of accumulating refractory materials by alternately dipping (such as sticking rice cakes) and accumulating refractory materials, but since the use of sodium silicate with low refractory degree is used, the molds produced are limited to those for melting at relatively low temperatures. Since the water resistance is low, it is difficult to use a hot-wax beeswax Autoclave beeswax method when dewaxing is carried out. In addition, by using an aqueous silica sol, the slurry is alternately coated with a slurry of a positively charged silica sol and a slurry of a negatively charged silica sol, followed by sanding. Although the method has been proposed, it is impossible to adopt caloric deswax and autoclavable deswax in dewaxing due to poor fire resistance, and the strength is also low because only thermal shock can be used. In addition, the method proposed in Japanese Patent Laid-Open No. 45-41505 has the drawback that interlayer peeling and foaming cracking occur. The inventors of the present invention invented a method for improving the above-mentioned shortcomings in a quick mold making method and filed a patent as Japanese Patent Application No. 47-59818. This method has a molar ratio of 4 to 20 slurry of refractory powder and hydrolyzed alkyl silicate and refractory powder and SiO ₂ / Me ₂ O (Me is an alkali metal atom). This is a method of accumulating refractory materials by alternately dipping a prototype in a slurry of quaternary ammonium silicate containing caustic alkali or alkali silicate. By this method, it is possible to improve the degree of fire resistance and to prevent phenomena such as delamination, foam cracking, etc., but the stability of the slurry liquid is not sufficient, and it has difficulties in practical use.

It is an object of the present invention to provide an improved novel rapid mold making method. Another object of the present invention is that the slurry to be used has good safety, the mold to be produced has a high softening point, a high strength at high temperatures, extremely excellent fire resistance and water resistance, and a calorific dewaxing method and an automatic It is possible to adopt the collabtal method, etc. Moreover, since the strength of the mold is extremely good, even if the thickness of the shell is thin, cracks do not occur, and the mold collapse after the heat is injected. An object of the present invention is to provide a method for quickly producing an easy mold.

The present invention alternately or simultaneously coats A liquid, or A liquid slurry containing refractory powder therein, B liquid slurry containing liquid B or refractory powder contained therein, and refractory powder. , A method of manufacturing a mold characterized by forming a cumulative hardening refractory material.

A-liquid: A silica sol having a pH of 6 or less, which is water, a hydrophilic organic solvent or a mixture thereof as a dispersion catalyst, and an organic pool material and / or acid, which can be stably mixed thereto. Or gelling liquid B containing acid salt.

B liquid: A liquid which gels solution A containing silica sol having a pH of 7 or more using water, a hydrophilic organic solvent or a mixture thereof as a dispersion medium and an organic pool material which can be stably mixed thereto. In other words, A and B liquids are stable liquids or slurry liquids alone, and such a hardened coating layer cannot be obtained in a circular shape by itself. However, the cumulative hardened coating layer is formed by advancing gelation by contacting A and B liquids. Will form.

As a silica sol having a pH 6 or less of water, a hydrophilic organic solvent or a mixture thereof contained in the solution A of the present invention as a dispersion medium, a mole of SiO ₂ / M ₂ O (M denotes a monovalent alkali metal atom) A ratio of 50 or more and a SiO ₂ content of 10 to 60% is used, and a specific example thereof is Snowtecken-0 (trade name: Japan). "Snowtechken-0" is pH 2 It is an acidic aqueous silicazol containing almost 20% by weight of SiO ₂ and 0.03% by weight, and almost no alkali metal.Metalol silicate and isopropyl alcohol silicate having a pH of about 3 when a small amount of water is added. Sol and silica sol containing organic acids such as ethanol, ethanol, ethylene glycol, acetic acid, uilic acid and inorganic acids such as chlorine, phosphoric acid, and nitric acid, and the like. PH 6 or less by adding grass It was good.

As an organic paste material which can be safely mixed with the above-mentioned pH 6 or less silica sol contained in the liquid A of the present invention, a water-dispersible resin emulsion zone is particularly effective, and a pH of 2 to 6 is preferable. Vinyl acetate alone and a co-polymerized resin. Examples of the gelling agent phosphoric acid include inorganic acids such as phosphoric acid, sulfuric acid, acetic acid and silicic acid, and acetic acid and acid. Examples of acid salts include inorganic acid salts, that is, aluminum phosphate. And acid salts of organic acids such as aluminum chloride. It goes without saying that the content of these gelling agents requires the concentration and amount to gel the B liquid. In addition, when the organic material of the gelling agent is mixed with the liquid B. It is preferable that these themselves also gel, and it is particularly preferable that when the acid or acid salt of the gelling agent is mixed with the liquid B, it is agglomerated by itself or reacts with the components of the liquid B to form a salt or a new compound. .

The pH of the liquid A needs to be 6 or less, and about 4 to 1 is particularly good.

As a silica sol containing water having a pH of 7 or more, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium contained in the liquid B of the present invention, SiO ₂ 10 to 60 wt% SiO ₂ / M ₂ O (M Refers to a monovalent alkali metal atom) and a moIe ratio of 5 to 300 is used, but in addition to amines, quaternary ammonium hydroxides, guanosulfs, maltporins, figerisoms, and (Ba (OH) ₂ Or the like, and the like may be used. Specific examples thereof include Snowtex-30 (trade name: Nissan Chemical Products). Snortex-30 is an alkaline silica sol of 30 wt% SiO _{2 and} 0.4 wt% Na ₂ O at a pH of 8.5 to 10.5. Examples of the hydrophilic organic solvent dispersant include monohydric and polyhydric alcohols such as methanol, ethanol, isopromanol, glyceline, glycol, and dimethylformamide.

As an organic pool material which can be stably mixed with the above-mentioned silica sol of pH 7 or more contained in the liquid B of the present invention, a water-dispersible resin emulsion zone is particularly effective, and an acrylic ester ester of acrylic acid having a pH of 8 to 12, Acrylic ester co-polymer resin emulsion, synthetic rubber latex, emulsion zone which is ethylene vinyl acetate co-polymer are effectively used. In addition, many neutral to alkaline water dispersion type synthetic resin emulsions are used.

PH of liquid B should be 7 or more, and generally about 8 to 12 is appropriate, but pH 12 or more can be used. An alkaline substance, for example, an alkaline paste material, may be added to a pH of 6 or less, so that the pH is 7 or more. The larger the pH difference between the liquid A and the liquid B can effectively carry out the object of the present invention.

As the refractory powder mixed in the liquid A and / or the liquid B, the refractory powder used for general precision casting is used. For example, there are zircon, silicate zircon, alumina silica, silica, chamotte, and many others, and particles of various sizes are available from these fine powders to particulates. The same applies to the refractory powder used for sanding.

In addition, the liquid A and the liquid B of the present invention may be used in combination with other additives such as a surfactant, an antifoaming agent, a clay lowering agent, and a thixtropase.

In the method of the present invention, it is necessary to contain the silica sol together with the liquid A and the liquid B, and when the liquid lacking this is used, it is impossible to obtain a precise, hard and uniform mold. That is, the obtained mold has a close laminated structure, and peeling, swelling, and the like occur when detaching at the boundary of the layer, making it difficult to obtain a desirable shell. In addition, the liquid A and the liquid B need to contain an organic paste material, but in addition to acting as a gelling agent, they work together with the silica sol to form a composite binder to achieve the purpose of the present invention. When the gelling action is not sufficient in the organic paste material, the A solution capable of gelling liquid B can be obtained by containing an acid or an acid salt as a gelling agent, but it is more preferable to use an organic paste material having gelling action. The same applies to the organic pool material used for the liquid B.

In preparing the mold in the method of the present invention, it is sufficient to advance the gelation to the state that does not cause the relaxation phenomenon within 10 minutes after the contact of the liquid A and the liquid B.

In the method of the present invention, either A liquid or B liquid may contain no refractory powder, but the liquid in this case acts only as a gelling liquid, and the coating layer of the liquid adheres to the refractory powder by sanding. .

According to the method of the present invention, the above-mentioned liquids A and B are alternately coated or spray-coated to form a coating layer, or alternately immersed in the liquids A and B to form a coating layer. Either A liquid or B liquid may be used first. Or what is necessary is just to sand as needed, since the coating layer of liquid A or liquid B was formed. In other words, when cumulative coating is performed in an alternating manner,

1. Repeat A-processing-sanding-B-processing-sanding

2. A liquid treatment-sanding-B liquid treatment is repeated

3. A liquid treatment-B liquid treatment-Sanding is repeated

4. In addition, A liquid B liquid and a refractory powder may be repeated at intervals in an arbitrary processing procedure.

Another method of the present invention is to apply or spray A and B solution simultaneously to form a coating layer and immediately gel and accumulate it. Also in this method, this coating layer can be formed at intervals and sanded as necessary to effectively accumulate refractory materials.

1. Simultaneous treatment of solution A and solution B-repetition of sanding

2. According to the simultaneous treatment of the liquid A, liquid B and the refractory powder, it is possible to form a lattice coating layer.

When the refractory material accumulates in the method of the present invention, the gelation of each layer proceeds quickly and surely, and no slurry flows out regardless of sanding, and even if the prototype is removed in the dewaxing process, there is no uniformity or swelling. Molds with excellent water resistance and extremely high strength are obtained. In addition, the mold obtained by the method of the present invention is extremely easy to collapse after pouring. Therefore, by the method of the present invention, the intended mold can be applied to the vacuum injection method, and also particularly to the casting of high melting point metal.

Next, the Example of this invention is shown.

Example 1

1.Production method of liquid A and liquid B

Using each of the ingredients and the amount used in Table 1, first put a silica sol in a 10 liter cylindrical container with a stirrer, stir at a rate of 60 R.PM, add a gelling agent, and if necessary, a surfactant and an antifoaming agent. (Iii) was added, and then refractory powder having an average particle diameter of 250 mesh was added and stirred for 30 minutes. After standing overnight, the mixture was stirred again to prepare a slurry.

TABLE 1

* 1: Vinyl acetate emulsion, 50% solids

* 2: Acrylic styrene styrene emulsion, solid content 50%

* 3: Synthetic rubber tex, solid content 30% (made by Nippon Pharmaceutical)

* 4: acrylic emulsion, 50% solids (made by Marudomo Chemical)

* 5: ethylene vinyl acetate emulsion (marumodo chemical system)

* 6: surfactant (Nippon fat and oil)

* 7: Antifoam (Nisei Sankyo)

1. Fabrication of molds

Four A beeswax models were first immersed in A solution, while A and B liquids described in Example 1 column of Table 1 above were placed in a 5 L wide inlet polyethylene bottle with a stirrer and slowly stirred at 60 R.PM. After soaking, pull it out and sand it with Jill Consand # 80, leave it for 3 minutes, immerse it in liquid B and completely immerse it, sand it again with Jill Consand # 80, and leave it for 3 minutes and then go back to the third coating process. After immersed in A solution, it was pulled out, sanded with high purity alumina sand having a particle diameter of about 0.5 m / m, and left for 3 minutes. After the fourth coating, the solution was impregnated with sand and sanded in the same manner as in the third coat. As a coating process, the solution is impregnated and sanded with a high purity alumina sand having a particle size of about 1.0 m / m, and after 3 minutes of standing, the solution is impregnated with sand as the sixth coating process (without sanding).

As a comparative example, a shell is created from the above-mentioned pieces at all except that phosphorus B liquid is used for the comparison described in the column of the first table Example 1 column.

The two shells of the present invention and the comparative example were heated to 900 ° C., each side of which was uncoated in a de-waxing furnace, and the de-waxed was put in about 5 minutes, and the shell was observed. As a result, the shell according to the method of the present invention had no cracks and no swelling at all, but the shell of the comparative example swelled at the dewaxed surface, and peeling occurred at three places. As a result of de-waxing in a hot water pressurized kiln of 150 ° and 7 kg / cm 2 with respect to the remaining two pieces, the shell of the present invention almost softened. It could not be waxed without cracking. However, the shell of the comparative example was softened considerably and there was no crack, but the mold was deformed and could not be used as a shell.

Although the shell according to the method of the present invention was extremely high in the strength of the produced form, collapse of the shell after pouring was easy.

Example 2

The solution A and B described in Example 2 in Table 1 above was used to coat the wax model in the same manner as in Example 1, but the coating process of each solution was more vigorous and faster than other coating processes. Even when impregnated, taken out and sanded, the slurry on the surface did not flow at all. In addition, the shell of the waxy wax which was favorable also in Example 1 was able to be manufactured.

Example 3

Using the liquids A and B described in Example 3 in Table 1 above, the wax model was coated in the same manner as in Example 1. In this embodiment, the liquid A does not contain the refractory powder, and the gelling material contains 0.15 kg of 50% sulfuric acid (H ₂ SO ₄ ) instead of the organic grass material. The gelation of each coat was reliably fast, and no slurry was flowing on the surface, and the resultant shell after the dewaxing was able to produce the same good shell as in Example 1.

Example 4

A and B liquids described in Example 4 column of the first table mentioned above were put in separate spray guns, and a mold release agent was previously applied to a wooden model used in the test procedure. , A and B are simultaneously sprayed at 200 g / m 2 each and immediately sanded with Jilcon powder 80 # and left for 5 minutes, and the same operation is also repeated twice. However, the coating amount of the liquid A and the liquid B is 800 g / m2 from the second time, and the sand used for sanding is high purity alumina sand having a particle diameter of about 0.5 m / m in the second time, and a particle diameter of about 1.0 m / in the third time. High purity alumina sand of m was used. In addition, the inner mold was masticated by coating water glass, silica and wet silicon powder with a thickness of about 50 m / m on the coated surface. Even after mold release in the wooden mold, even after firing at 800 DEG C for 6 hours, it became a good mold with no cracking at all.

Claims (1)

As described above in the main text, the following A liquid or A liquid slurry containing refractory powder therein, B liquid slurry or B liquid slurry containing refractory powder therein and refractory powder are in a circular form. A method of producing a mold, characterized in that to form a cumulative cured refractory material by coating alternately or simultaneously. Solution A: Gelling a silica sol having a pH of 6 or less as a dispersion medium with water, a hydrophilic organic solvent or a mixture thereof, and an organic grass material which can be stably mixed therewith, and B liquid containing an acid or an acid salt. Liquid Solution B: A solution which gels solution A containing silica sol having a pH of 7 or more using water, a hydrophilic organic solvent or a mixture thereof as a dispersion medium and an organic paste material which can be stably mixed thereto.