JPS6082247A - Organic self-curing sand for production of casting mold - Google Patents

Abstract

PURPOSE:To obtain org. self-curing sand which permits integration of formation of a sweeping mold, etc. and sand control by adding a specific amt. of a crosslink type acrylic acid polymer thickener, etc. to the self-curing sand consisting of refractories, an org. binder such as furan resin or the like and an acidic curing catalyst. CONSTITUTION:Refractories A such as silica sand or the like and 0.05-0.5wt%, based on the weight thereof, a liquid thickener DE prepd. by liquefying a crosslinked type acrylic acid polymer thickener, etc. with a solvent such as xylene, etc. are kneaded. A curing catalyst C is added to the kneaded matter under kneading and further a binder B such as furan resin is added under kneading to obtain the intended org. self-curing sand F. Since the thickener D is incorporated into the self-curing sand, the viscosity of the sand is increased and the sand F is usable for forming a sweeping mold and strickle. Integration of said formation and sand control is made possible and the rate of recovering and reconditioning the same is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to organic self-hardening sand for mold production containing an organic thickener.

[Invention 0 Technical Background and Problems Therein] The general constituents of sand for mold making are granular refractories such as silica sand and organic or inorganic binders. auxiliary additives are added. Organic self-hardening sand is made by using synthetic resin such as furan resin, phenol resin, urea resin, or a mixture thereof as a binder in granular refractory material such as silica sand.
This sand is made by adding and kneading an acidic curing catalyst to this binder.

The organic self-hardening sand containing refractory sand, an organic binder, and a binder W is charged into a mold in a fluid state and hardened to the required strength at room temperature. This organic self-hardening quadruple contains almost no water, reducing the energy consumption required to dry the mold, and since the organic binder resin and catalyst remain on the surface of the refractory after use, recycled sand is used. This has the advantage of reducing the amount of binder and catalyst used.

However, since the material is extremely crystalline and fluid, when molding it using a wooden model, there is no choice but to use a molding method that uses an existing model. In other words, it is only suitable for a method in which sand is poured around a wooden model (current model) having the same shape as the casting to be made. On the other hand, organic self-hardening is used in the mawashi molding method, in which a sand mold is made by rotating a plate attached to a shaft, and in the raking mold (pulling mold) molding method, in which the sand mold is scraped off using a guide plate and a scraping plate using a gauge. Sand is not suitable. Therefore, even if the shape of the product is suitable for the rotary molding and drawing molding methods, the only way to form it using organic self-hardening sand is to use the expensive and laborious molding method. Conventionally, when the product shape is to be molded using a rotating mold or a drawing mold K:4, a pyrolithic binder such as cement or water glass is used. To this end, at the R41 product factory, we separate sand for organic η binders and sand for non-primitive binders, and manage the sand by crushing sand blocks, sieving, and collecting them, and unifying them. Can not do it. This is because organic self-hardening sand has a pH of 3i! While cement-based self-hardening sand and water glass-based self-hardening sand harden in an alkaline range of pH 13 to 14, green sand with contradictory hardening mechanisms can be mixed together. This is because sand management such as collection causes problems in the quality of subsequent molding and castings.

[Purpose of the invention]

The present invention has been made to solve the problems of the back base technology mentioned above, and its purpose is to have a viscosity and pot life suitable for the rolling mold and pull molding methods, and therefore, It is an object of the present invention to provide a self-hardening quadruplex for manufacturing molds that can unify the management of 'C' sand in the casting process.

[Summary of the invention]

In order to achieve the above purpose, a viscous material is included in the organic self-hardening sand so as to have a viscosity suitable for the molding method of door molds and drawers, and the following conditions are met for this viscous material. It has to be satisfying.

(a) By including a viscous organic substance, the mold after molding should have good formability without collapsing at the edges, tips, vertical parts, and corners.

(b) In the rolling and pulling molding methods, it is desirable to extend the usable life of the sand since it requires a lot of time from the start of molding to the completion of the molding process. Therefore, it is possible to set the pot life of the sand in consideration of the shape, size, and molding man-hours of the cast product.

(c) Generally, when organic substances other than binders are added to sand, the strength required as a mold decreases. Therefore, it is possible to ensure the necessary strength even if this viscous organic matter is included in the sand.

b) Even if viscous organic matter is included in conventional organic self-hardening sand, it will not have a negative effect on the properties of this organic self-hardening sand.

As a result of testing and research on various viscous materials, the present inventors found that organic thickeners consisting of at least one of crosslinked acrylic acid polymers, sodium polyacrylate, polyethylene oxide, and polyvinylpyrrolidone were used as organic thickeners. The present invention has been completed by discovering that the above-mentioned conditions can be satisfied if the organic self-hardening sand is contained in four layers of organic self-hardening sand.
It consists of an organic binder consisting of at least one of the following: a furan resin, a phenol resin, and a urea resin, and an acidic curing catalyst of one proportion to the binder! The organic self-hardening sand for mold production is characterized by containing an organic thickener consisting of at least one of a crosslinked acrylic acid polymer, sodium polyacrylate, polyethylene oxide, and polyvinylpyrrolidone.

[Detailed description of the invention]

The refractories used in the present invention include those used as sand grains in foundry sand, usually silica sand, and the like. In the present invention, either new sand, recycled sand, or a mixture thereof may be used for the refractory.

The periolated binder in the present invention is a specific polymer generally used for organic self-hardening sand, preferably an initial polymer of furfuryl alcohol, a phenol such as furfuryl alcohol and phenol, cresol and xylenol. Alternatively, there are co-compounds with urea, initial polymerization products of phenols and formaldehyde, co-polymerization products of formaldehyde, phenols and urea, and initial polymerization products of urea and formaldehyde. Containing an organic thickener shows a tendency for the mold strength to be lower than that of K. Therefore, it is desirable to increase the binder by some amount. For example, the amount of the binder added is preferably 1.0 to 1.5 parts by weight per 100 polymerized parts of the refractory.

The acidic curing catalyst used in the present invention has the function of curing the binder of organic self-hardening sand during molding, and is preferably an inorganic acid such as phosphoric acid or sulfuric acid or an organic acid such as benzenesulfonic acid or toluenesulfonic acid. be.

The organic thickener used in the present invention is one that increases the viscosity of self-hardening sand, and is made of at least one of cross-linked acidic polymer, polyacrylic/I/iVJ sodium, polyethylene oxide, and polyvinylpyrrolidone. It is.

The cross-linked acrylic acid-based polymer in the present invention uses acrylic acid or methacrylic acid with a quadrupled delta or less as a monomer, and can be combined with these monomers with or without addition of a modifying monomer such as ethylene. It is cross-linked and copolymerized in the presence of a polymerization initiator in a suitable medium with a polyfunctional organic cross-linking agent that provides a polymer with a so-called three-dimensional structure by copolymerization. Examples of cross-curing agents include divinylbenzene, divinyldioxane, sucrose polyallylconythyl, pentaerythryl 3-polyallyl ether, triallyl cudianurate, glycol diaryl ether, etc. Polymerization initiators include , inorganic and taxable peroxides, and organic azo compounds are used. Frame JJ
Fi-J Acl)) Commercially available acid-based polymers include Carboball (trademark) manufactured by Gutdrich in the United States, Shunron (trademark) manufactured by Nippon Junko Co., Ltd., and No. - Examples include Ibis Wako (trademark). When a cross-linked acrylic hexavalent polymer is used as an organic thickener,
The meter is preferably 0°0 for a refractory of 100 kg.
3 to 0.7 parts by weight, more preferably 0.05 to (L5
It is a heavy world club.

Here, below the minimum limit, the formability of the mold is poor, and on the other hand,
Exceeding the maximum limit increases viscosity and reduces work efficiency.
It also increases manufacturing costs.

There are 4 types of sodium polyacrylate! When used as a thickener, its good addition is preferably from 0.3 to 5.0 parts by weight, more preferably from 0.5 to 3.0 parts by weight, per 100 parts by weight of the refractory. Department. Here, if it is less than the lowest limit, good formability of the mold cannot be obtained, and if it exceeds the highest limit, the manufacturing cost of sand will be increased.

In the present invention, when polyethylene oxide is used as a thickener, 0.2 to 2
．． Good moldability and mold strength can be obtained at a content of 5 parts by weight, particularly 0.3 to 2.0 parts by weight. Below this minimum amount, there is a limit to the height of the vertical surface of the mold, while above this maximum amount, workability and economy are compromised.

In the present invention, when the content ratio of polyvinylpyrrolidone is preferably in the range of 2 to 4.0 parts by weight, preferably 0.3 to 3.5 parts by weight per 100 parts by weight of the refractory, Obtains good formability and mold strength. Exceeding this maximum limit impairs workability and economy, while below this minimum limit there is a limit to the height of the vertical surface of the mold.

The organic self-hardening sand in the present invention is obtained by adding and kneading an organic thickener in a solid form such as powder or granules, or preferably in a liquefied state with a solvent (including a dispersant) to a refractory. There may be. Examples of this solvent include liquid paraffin, xylene, toluene and benzene.

The ratio of the solvent and the thickener must be set to a viscosity below the maximum transfer viscosity of the metering pump during addition and mixing, and for this reason, the thickener should be 5 to 50% by weight and the solvent should be 95 to 50% by weight.
It is desirable to add.

Next, an example of the method for manufacturing an organic self-hardening mold according to the invention will be described in detail with reference to the accompanying drawings. Figure 94+1 shows an example of a process diagram of the manufacturing method. As shown in this figure, refractory A and thickener or refractory A and solvent E can be used to
Alternatively, the dispersed and liquefied liquid thickener DA is mixed in the kneading step (1). Next, this mixer is subjected to a crosstalk process (
2) So? 1lJI compound 114a is added and kneaded. Further, kneading process: #(31), add and mix the binder B (Ma 1!) to obtain the target material, A4:1-self-hardening sand F. In addition, each rJ, The addition order of 110 is not limited to the above and is arbitrary, and the refractory A, the binder B, the curing catalyst C, and the thickener or liquid thickener may be added and kneaded at the same time.

〔Example〕

Next, the present invention will be specifically explained using Examples and Reference Examples. The test materials used are as follows.

(A) Refractory; 95% by weight of recycled sand + Mogami silica sand 5S landscape (
B) Organic binder; urea 7 run resin (+340B, manufactured by Kao Riacre Co., Ltd.) (0) N(tJ[; paratoluenesulfone Ii, 1
(0-14, manufactured by Kao Riacre Co., Ltd.) (D) Organic thickener; crosslinked acrylic/L/acid polymer (
Powder, Aiko Pure Chemical Industries, Ltd.! A) Sodium polyacrylate (powder, manufactured by Aiko Pure Chemical Industries, Ltd.), polyethylene oxide (powder, manufactured by μTetsu Kagaku Kogyo Co., Ltd.), polyvinylpyrrolidone (powder, reagent) (E) Solvent; liquid paraffin ( Matsuzai Oil Research Institute Co., Ltd.), xylene (reagent), benzene (reagent), toluene (
Reagent) Examples 1 to 15 Using the above-mentioned test materials, the organic self-hardening sand of the present invention was prepared using the procedure shown in FIG. Made by II. Examples 1-1
2, the refractory A and the thickener are kneaded in step 1 to 10
Knead for seconds, immediately add curing catalyst C in step 2, and
The mixture was kneaded for 1 hour. Next, in the mixing step 3, binder B was added and kneaded for 30 seconds to obtain organic self-hardening sand 1. Kneading was done using a kneader (product type) for 300,067 times of mixing #1! I went to Italy. The blending ratio for each by is shown in the first column.

@Table 1 Organic self-hardening mold formulation (parts by weight) Examples 13 to 1
In Example 5, the same procedure as in Examples 1 to 12 was carried out except that the thickener was dissolved or dispersed in a solvent at the ratio shown in Table 2 and used as a liquid.

The blending ratio of each component is shown in Table 2. ), organic self-hardening sand with increased amounts of organic binder and curing catalyst (Reference Example 2), and conventional inorganic self-hardening sand (Reference Example 3) were prepared. The blending ratio of each ingredient is 3.4.
Shown in the table. Note that this inorganic self-hardening sand was prepared by kneading refractories and cement, and then adding water.

Table 3 Table 4 Compounding of sand in Reference Examples 1 and 2 Table 4 Compound evaluation test of cement self-hardening sand (a) Formability test Formability using the self-hardening sand of Examples 1 to 15 and Reference Examples 1 to 3 We conducted a test. 200 (
1) A test piece of x 50 (w) x 25 (h) cm (density 1.58 g/am3) was prepared. The test drive method was carried out as shown in Figure 2. That is, a vinyl sheet 12 is spread on the measuring table 11, and this sheet 12 is placed on the measuring table 11.
Place the test piece 13 on top. The test piece 13 is made to protrude from the measuring table 11 by moving the sheet 12 toward the lower side in the direction of the arrow. The protruding tip 15 of the test piece breaks halfway due to the weight of the sand and falls onto the pedestal 14. Measure the weight of the sand that fell. The results are shown in Table 5.

Generally speaking, the criteria for suitability for rolling mold and pull molding methods are that if the height of the vertical surface of the mold is 150 mm or less, a falling weight of 35 to 38 g is required;
0 mm requires a weight of $38 to 40 g, and a height of 300 mm or more requires a weight of 40 g or more.

As can be seen from Table 5, all of the organic self-hardening sands of Reference Examples 1 and 2 that do not contain a thickener have poor moldability and are not suitable for the rotary mold and pull mold molding methods.

On the other hand, the organic self-hardening sand of the present invention has a weight in the range of 36 to 52 g, showing relatively good formability.

Note that the inorganic self-hardening sand of Reference Example 3 also exhibits high moldability at 56 g. In addition, it was observed that, in general, sand with poor formability breaks and scatters on the pedestal i4, whereas sand with good formability maintains its shape even if the broken tip falls.

(b) Pot life test The self-hardening sands of Examples 1 to 15 and Reference Examples 1 to 2 were used to test pot life. That is, test pieces (diameter 5Q mm x height 50 mm) were formed by filling sand that had been mixed for various times into wooden molds, and the test pieces were left to stand for 24 hours. The pot life was determined from the elapsed time during which gun-shaped strength of 20 kg/am2 or more could be maintained after being left for U hours. The results are shown in Table 5.

Compared to the current molding method, the rotary mold and pull mold molding methods involve more manual work and take longer to complete from the start of molding, so an extension of the pot life of the sand is required. As shown in Table 5, in Examples (excluding Example 9), Reference Examples 1 to
It can be seen that the pot life is considerably improved compared to No. 2.

(c) Test drive for strength over time and surface stability Tests for strength over time and surface stability were conducted using the self-hardening sands of Examples 1 to 15 and Reference Examples 1 to 2. After mixing, 6 sand was put into a wooden mold, and after 1 hour, it was taken out from the mold and formed into a test piece (diameter 59 an x height 50 mm).

After 2 hours, 4 hours, and a free time, the pressure and strength of the test piece were measured.

Further, the fii of the above test piece which was left to stand for 24 hours was measured, and then the weighed test piece was placed on a 10 mesh sieve installed in a rotor tube tester and the test piece was vibrated for 2 minutes. The weight of the test piece was measured again to calculate the weight loss due to vibration.

The surface stability (S, S, engineering) was determined from this weight reduction.

These results are shown in Table 5.

Table 5 Evaluation test results As is clear from Table 5, conventional self-hardening sand (Reference example 1
) and self-hardening sand with an increased amount of binder (Reference Example 2), the mold strength of the self-hardening sands of Examples 1 to 15 is relatively low, and the strength further decreases as the organic thickener is increased. There is a tendency to However, it is possible to prevent the strength from decreasing by slightly increasing the amount of binder, and the mold strength generally required is 20 kg /
Cm" or more, 25 kg/cm is sufficient in the case of a large size. Therefore, Examples 1 to 5 all passed the test in terms of strength.

Regarding the surface stability, if the surface stability is approximately 90:1115, the mold can withstand the flow rate and pressure of the molten metal and can produce a cast product with a smooth surface. -1°) Casting test (a) Using the self-hardening sand of Example 3.4.7, the maximum diameter was 9QQ by the rotary molding method as shown in Figure 3(a).
Inn That is, a metal frame 21 necessary for manufacturing a mold is prepared, and a pedestal 22, which serves as a reference for the placement of the metal frame 21, is placed on top of a self-hardening mold 25 mounted in the center, and is placed opposite to the pedestal 22. Spisidoru 27 with upper support member installed and a rotating mold attached to these
Attach it so that it can rotate freely, replenish the self-hardening paper part without rotating the turner W24, and continue molding as it progresses. A mold coating agent was applied to this mold, an upper mold 26 was placed thereon, and the mold was poured.

(1)) Using the self-hardening sand of Example 1O113 and 16, the molding method was performed as shown in FIG. l1lx height 3QQ
A mold for a casting having a weight of approximately 1.058 kg was manufactured. Similarly to (&) above, a guide plate 32 serving as a height reference is set on the metal frame 31, and while moving the drawer mold 33 in the vertical direction with respect to the 1st and 4th surfaces along this guide plate 32, the self-hardening Sand: A mold was made by adding I4. After the P type is cured, apply a water-soluble mold coating agent, and after drying the Baniner, apply the upper mold 3.
5 and poured hot water.

Both of the molten metals in (a) and (1)) are made of material Go (PC
-30 equivalent), and the casting temperature was 1300°C (0, PlM). The presence or absence of defects in the cast products of each category was observed after the Cy9atplast treatment and after the entire surface pattern processing.

As a result, no defects were found in any of them.

〔Effect of the invention〕

The following effects can be obtained by the present invention.

(b) By including the organic thickener according to the present invention in the zero-reef mold, the viscosity of the organic self-hardening sand is increased, and even organic self-hardening sand can be used in the molding method of turning molds and pulling molds. be able to. In addition, the moldability is improved, and therefore it becomes possible to arrange the food in complicated ways by hand. Furthermore, the pot life of the sand is extended, and the pot life can be adjusted with consideration given to the shape, size, and number of molding steps of the casting convex.

(b) Conventionally, highly fluid organic self-hardening sand has been used in the current molding method, while inorganic self-hardening sand has been used in the door-to-door molding and tension molding methods. management was in place. However, with the organic self-hardening sand of the present invention, organic self-hardening sand can be used in any molding method, making it possible to unify sand management in a foundry and further increasing the amount of sand recovered and recycled. .

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an example of the method for preparing organic self-hardening sand of the present invention, FIG. 2 is an explanatory diagram of a moldability test, and FIG. Explanatory diagram of the law, and the third
Figure (1)) is an explanatory diagram of the pull molding method used in the casting test. 11... Measuring table, 12... Vinyl sea), 13.
... test piece, 14... cradle, 15... broken test piece, 21 river metal frame, 22... pedestal, 23... upper support member, 24... rotary mold, 25...・Self-hardening sand, 26・・
・Upper mold, 27... Spindle, 31... Gold frame, 32
...Guide plate, 33...Draw mold, 34...Self-hardening sand, 35...Upper mold. Applicant's agent Kiyoshi Inomata

Claims (1)

[Scope of Claims] Organic self-hardening sand for mold manufacturing, comprising a heavy refractory, an organic binder made of at least one of furan resin, phenol resin, and urea resin, and an acidic curing catalyst for the binder. In, crosslinked quadrilylic acid polymer, sodium polyacrylate, polyethylene oxide 1.・
' and an organic thickener consisting of at least one of polyvinylpyrrolidone! ] 1. Organic self-hardening sand for mold manufacturing. 2. Organic thickener quadruple cross-linked acrylic acid polymer,
The organic self-hardening sand for mold manufacturing according to claim 1, wherein the organic self-hardening sand is contained in an amount of 0.05 to 0.5 parts by weight per part of the refractory material looMr. 3. Claim 1, characterized in that the organic thickener quadruple sodium polyacrylate is contained in a ratio of 0.5 to 3.0 parts by weight based on the weight of the refractory zoo. Self-hardening sand for making molds. 4. Manufacture of a gate type according to claim 1, characterized in that polyethylene oxide is contained as an organic thickener in a proportion of 0.3 to 2.0 parts by weight per 100 parts by weight of the refractory. Self-hardening sand for use. 5. Polyvinylpyrrolidone as an organic thickener, 0.3 to 3 parts of refractory toon'. s7t, in a proportion of 9 parts. 6. Organic self-hardening sand for mold production according to any one of claims tB1 to 5, characterized in that it is made by adding and kneading a valuable thickener liquefied with a solvent. 7. Organic self-hardening sand for production of the same type as claimed in claim 6, characterized in that the solvent is a fluidized quadruple fin. 8. Make sure the solvent is xyleno! 9. Organic self-hardening sand for mold production according to claim 6, characterized in that the solvent is benzene. Hard sand. 10. The bound self-hardening quadruple for manufacturing molds according to claim 6, characterized in that the solvent is 0-technique.