JPS5817694B2 - Igatano Sakuseihouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for rapidly producing a mold by accumulating a refractory material on a master mold.

Regarding the so-called rapid mold manufacturing method by alternately immersing a master mold in two types of slurry that contain a refractory and a binder and have the property of mutually gelling, thereby accumulating a gelled layer of the two types of slurry on the master mold. Various methods have been proposed in the past.

As one method, Japanese Patent Publication No. 45-41505 describes a method in which a master mold is alternately immersed in a slurry of an acidic solution of ethyl silicate and an alkaline solution of sodium silicate to form a cumulatively hardened refractory material.

However, this method has the drawback that delamination, foaming cracks, etc. are likely to occur in the mold.

As a countermeasure, S+02 in the alkyl silicate binder
This can be improved by lowering the concentration, but this is not an appropriate method because the strength of the mold after firing decreases.

This can also be improved by allowing 2 to 4 days for drying before the flD heat furnace/autoclave hot water treatment, which is the lower stage of demolding, but this has the disadvantage of not being quick enough.

The present inventors investigated various reasons why delamination, foaming cracks, etc. are likely to occur in molds produced by a rapid mold manufacturing method in which alkyl silicate is used as the binder for one slurry and alkali silicate is used as the binder for the other slurry. As a result, the alkyl silicate itself is hydrophobic, and when it comes into contact with an aqueous binder slurry with a pH of 8 or higher, a hard gelation occurs rapidly at the interface, and as a result, the gel exhibits strong binding strength, but on the other hand, the alkyl silicate hardens. Alcohol inside the body
This causes the cured product to contain alkyl silicate, etc., and the gel of the aqueous binder slurry with a pH of 8 or more surrounds the outside, making it increasingly difficult to remove the alcohol, alkyl silicate, etc. in the cured product. ,
If the final coating is not left to dry for a sufficiently long period of time, the above-mentioned included substances will be explosively combusted by the heat removal of dehysteresis type i, which will easily cause the cumulative layer to collapse, crack, or crack. It was concluded that even when the dehysterization method is used in hot water or autoclave, delamination is more likely to occur due to the lack of homogeneity between the layers.

A method described in Japanese Patent Application Laid-Open No. 49-20025 is an improvement over the drawbacks of the method of Japanese Patent Publication No. 45-41505.

This method uses quaternary ammonium silicate instead of alkali silicate to improve the homogeneity between the cumulatively cured coating layers and solve the above problems, but sufficient care is not taken during drying. In addition to the disadvantage that the gel before drying is soft and easily crumbles, quaternary ammonium salts are expensive, so there has been a desire for an improved method for making molds that is more practical.

As a result of further studies to improve the drawbacks of using an alkyl silicate binder in one slurry, the present inventors found that by adding a metal oxide sol such as silica gel at a pH below 1 to the alkyl silicate binder. We have found that the above problems can be solved.

An object of the present invention is to provide a rapid method for producing a mold that has high adhesion and strength without causing delamination, foaming, or cracking.

This invention applies the following liquid A or a slurry of liquid A containing a refractory substance, the liquid B below or a slurry of liquid B containing a refractory substance, and a refractory substance alternately or simultaneously on a master mold. A method of making a mold, characterized in that a cumulatively hardened refractory material is formed by coating.

Solution A: Al2O3,5i02, T with a pH of 6 or less using water, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium
A liquid containing a t 02 or Z r 02 sol and a C1-3 alkyl silicate solution.

Bi...Silica sol with a pH of 8 or more using water, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium! A liquid containing an alkaline silicate solution.

The sol with a pH of 6 or less using water, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium used in the present invention generally has a concentration of about 10 to 50%, such as Al2O3, Si02, or Z.
Examples include sols such as r2O and TiO2.

The preferred mixing ratio of these metal oxide sols to the alkyl silicate is 90% by weight in the form of both oxides.
: 10 to 10 : 90.

When a metal oxide sol is used at a weight ratio of 90:10 or more, the binding strength decreases and rapid hard gelation becomes difficult to occur.

Furthermore, when a metal oxide sol is used below the above range, the drawbacks of the alkyl silicate binder cannot be improved.

As the alkyl silicate used in this invention, an alkyl silicate having a concentration of about 0 to 38, which has been commonly used in the past, can be used.

Common examples include methyl silicate, ethyl silicate, and propyl silicate, with ethyl silicate having particularly high industrial utility value.

The alkyl silicate can be used as is or partially hydrolyzed.

Hydrolysis may also occur when mixed with metal oxide sol.

In addition, when it is difficult to mix the alkyl silicate and the aqueous metal oxide sol uniformly, it is necessary to use a surfactant, a thickener, etc. in combination to make the mixture homogeneous.

Examples of silica sols with a pH of 8 or higher containing water, a hydrophilic organic solvent, or a mixture thereof in Bl as a dispersion medium include aqueous silica sol "Snowntex" (manufactured by Nissan Kagaku Shigyo Co., Ltd.) and "Ludtux" (manufactured by DuPont). company)
is a typical example.

These are generally 5iO220-50 weight ratio, 81027
M20 (M represents a monovalent alkali metal atom.

) molar ratio of 30 or more, silica particle size of 5 to 150; m!
t, and many use water as a dispersion medium, but methanol, ethanol, isopropanol, polyhydric alcohols such as glycerin, polyethylene glycol, acetone,
It is also possible to use dimethylformamide alone or in a mixture with water as a dispersion medium.

) As the alkali silicate to be contained in liquid B, there are sodium silicate, potassium silicate, lithium silicate, etc., which are generally called water glass, but generally 5iO220~
30 weight ratio and a molar ratio of 81027M20 of 2 to 4 is used.

i Whether to use silica sol or alkali silicate for liquid B may be selected depending on the fire resistance of the intended mold, and when silica sol is used, the fire resistance of the mold is improved.

The refractory material used in this invention refers to all commonly used refractory materials, and those in the form of fine powder, lumps, and fibers are used, and lightweight powder products can also be used.

In terms of components, Al2O3, S r 02, MgO, Cab
, ZrO2, etc. are the main components.

Powder products with a weight of 20 to 500 meters are often used.

In the slurry of this invention, a surfactant is used to improve the wettability of the refractory slurry to the original wax, and an antifoaming agent is also used to defoam the foam in the large-sized slurry, as well as to reduce the viscosity. It is also possible to use a thixotropic agent, etc. in combination.

In the method of this invention, either the A or B solution may not contain a fire-resistant substance, but in that case, the drained liquid simply acts as a gelling liquid, and the coating layer of the drained liquid is made fire-resistant by sanding. The substance will be resistant to adhesion.

When both liquids contain a refractory substance, they have the effect of mutually gelling and accumulating a refractory shell on the master mold.

The method of this invention is to form a coating layer by alternately applying or spraying the above-mentioned liquid A (or slurry) and Bl (or slurry) onto a master mold, or by alternately dipping the master mold.

There is no problem in using either A or B liquid first.

Also, if necessary, sanding with a fire-resistant material may be applied.

Another method of the present invention is to form a coating layer by simultaneously applying or spraying liquids A and B, which are immediately gelled and accumulated.

Also in this method, the refractory material can be effectively accumulated by applying or spraying the slurry intermittently and sanding as necessary.

The method for preparing the refractory material slurries of liquids A and B is almost the same as that in the general lost wax method, and will be described later as an example.

Although the effect of the method of the present invention that allows rapid production of a good template has not been clearly elucidated, it is assumed to be as follows.

In other words, when the binder liquid obtained by mixing an alkyl silicate binder and a metal oxide sol with a pH of 6 or less comes into contact with the other alkaline binder liquid, the cohesiveness of the gel produced is moderate. The gel from the metal oxide sol is mixed into the gelled silicate, forming a homogeneous cumulative gelled coating layer, and the remaining alcohol, alkyl silicate, etc. are easily removed.
This is presumed to be due to the fact that the amount of strain is also alleviated during combustion.

This invention is a method known as the lost wax method, in which a wax model is cumulatively coated with a refractory slurry to create a mold, and a rapid mold creation method in which a wax pattern is coated alternately with two types of slurry to form a cumulatively hardened refractory material. In areas including
This is an innovative rapid mold manufacturing method because it can be completed in one day, including the cumulative coating and several hours of dewaxing, whereas it previously took three days.

Moreover, by the method of the present invention, it is possible to replace a mold with high adhesion and strength without delamination or foaming cracks.

It goes without saying that this invention can also be applied to the field of mold making, which is known as the Shaw process.

Next, the method of the present invention will be described in detail with reference to Examples, but the method of the present invention is not limited to these Examples.

Examples and Comparative Examples Solutions A and B in Table 1 were prepared as slurries for accumulating refractory materials in Example 1.2.3 and Comparative Example 1.2.3.

The number in the table indicates the weight.

(1) Coating method 1) Examples 1 and 2 and Comparative Examples 1 and 2 While liquids A and B were placed in a 51 stainless steel beaker with a stirrer and slowly stirred using 50R, P, and M, six wax molds were placed. Each piece was first immersed in liquid A and coated with slurry, then taken up and sanded with zircon sand≠80 (in Example 2 and Comparative Example 2, 5 to 1.0
Sand with 0 mesh fused quartz powder.

゛After standing for 5 minutes, it was dipped in liquid B as a second coat to cover the slurry, taken up, sanded again with Zircon Sand 4I = 80, left for 5 minutes, immersed in liquid A again as a third coat, taken up, and the particle size was 0. .5 m/m chamotte sand (in Example 2 and Comparative Example 2, sanding was performed with 20 to 50 mesh fused quartz powder).

) After standing for 5 minutes, it is dipped in B liquid as a fourth coat, sanded in the same way as after the third coat, and dipped in A liquid as a fifth coat. Sanded with Q rYi/m chamotte sand, 5 minutes later immersed in B solution as the 6th coat,
After that, coating was completed without sanding to create a shell.

11) Example 3 and Comparative Example 3 A liquid A containing a refractory substance and a liquid B which does not contain a refractory substance and acts as a curing liquid were prepared in the same manner as in Example 1, and six wax patterns were separately placed on each of them. First dipped in liquid A, 2 minutes after taking it up, immersing it in liquid B, and 2 minutes after taking it up, sanding it.
The first coat was completed after being left for 5 minutes.

Thereafter, a shell was produced in the same manner up to the sixth coat.

For sanding, the first and second coats are zircon sand≠804
3rd and 4th coats with chamotte sand 0.5m/m, 5th coat
, 6 coats were applied using chamotte sand at 10 m/m.

(2) Dewaxing method [) Examples 1 and 3 and Comparative Examples 1 and 3 Two coated shells each were heated to a
Dewaxing was performed by placing the uncoated side downward in an electric furnace for dewaxing, which was preheated to υ°C, for about 7 minutes.

11) Example 2 and Comparative Example 2 The coated shells were dewaxed in 100°C1 hot water 10 hours after coating was completed.

(3) Observation results of the shells after dewaxing (Observation results of the shells according to Example 1 and Comparative Example 1) The results are shown in Table 2, and the shells prepared by the method of the present invention do not cause blistering even after drying for a short time after coating. An excellent shell was obtained with almost no delamination, whereas a comparative example was obtained after 72 hours with no blistering or peeling.

The shell according to Example 2 was hard and had no cracks or peeling, but the shell according to Comparative Example 2 had considerable blistering.

Table 3 shows the observation results of the shells of Example 3 and Comparative Example 3.

The results are generally similar to those in Table 2, indicating that the shell produced by the method of the present invention is superior.

In addition, without immersing the wax model in both solutions A and B of Example 3, apply A to the wax model using a paint spray gun in the same order as in Example 3.
The observation results of the dewaxed shells that were spray-coated with liquid B and sanded were also almost the same as in Table 3.

Claims (1)

[Scope of Claims] 1 The following liquid A or A containing a refractory substance therein.
A cumulative hardened refractory material is formed by coating a liquid slurry, Bl described below or a B liquid slurry containing a refractory material therein, and a refractory material on a master mold alternately or simultaneously. Mold making method. Solution A: Al2O3, SiO2, Tl with a pH of 6 or less using water, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium
A liquid containing a sol of O2 or ZrO2 and a solution of an alkyl silicate having 1 to 3 carbon atoms. Liquid B: A liquid containing a silica sol or alkali silicate solution with a pH of 8 or higher using water, a hydrophilic organic solvent, or a mixture thereof as a dispersion medium.