JPS5939445A - Core for casting and its casting method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shaping of molding materials, such as the production of metal and e-alloy castings, and to the provision of modern cores or inserts which are sometimes used therein.

More particularly, the present invention relates to providing cores or inserts for use in casting metals and metal alloys, such as light metals.

For the production of castings, it is well known to use cores or inserts lubricated with ceramic compounds, around which metals or alloys are cast, and after casting they are removed by mechanical means, e.g. is 1mi
It is removed by Type 11 drilling or, in the case of composite core moldings, by dissolution in an m-agent that does not react with the cast metal.

English 1chi] Special W! In specification f 1,005,136,
Powdered tricalcium silicate"! or a mixture comprising a precursor and a binder; to produce cores or inserts by molding and then firing the molded shapes at temperatures ranging from 1075°C to 1125°C; The cores thus formed are particularly useful in the casting of metals and alloys, such as aluminum and aluminum alloys, from which the cores are subsequently prepared in 50% nitric acid. A core removable by dissolution in an aqueous solution of caustic soda is described in British Patent No. 1.O13,938, according to which the core is made of titanium oxide. 30-70% and more than 1 cypress of cypress, calcium, strontium and magnesium are formed from a mixture comprising oxides or precursors of aluminum.British Patent No. 1, 07
No. 0,382 discloses that the core, with or without a mold integral with the core, is made of one or more oxides or oxide precursors of Group IIA metals and/or one or more , it is described that they can be produced by firing shaped bodies of zirconium oxide or silicates together with other refractory oxides or precursors. These cores are useful in casting nickel-based alloys;
The core is removed from these alloys by treatment with molten caustic soda or aqueous caustic soda or hydrofluoric acid. British Patent No. 1,115,441 describes molds and/or cores useful for metal and alloy castings, particularly aluminum alloy castings, which are formed from calcium phosphate and treated with nitric acid. Therefore, it can be removed from the formed casting. A suitable core for castings of group Ⅰ transition metals is described in British Time FF No. 1.299,901 Mei #111, and according to the invention, this core is made of alumina, magnesia and/or gMJ is made from zirconia and, after firing, treated with a carbonaceous material to retain a portion of the finely divided carbon or graphite in the inner and/or outer layers.

Cores and molds prepared according to these descriptions have been used throughout the city. Despite the success with these cores, in the metalworking industry, ten thousand of the well-known advantages of cores are often difficult to obtain by simply immersing them in water and thus in a water bath. There has been a growing demand for a core that can be easily removed from a molded object (7+) having an internal shape.

The object of the present invention is to provide a water-soluble core of this yuzu citron.

According to the present invention, the particle size distribution of the water-bathable salt in the refractory is such that the granules have a particle size of 13 to 750 μm, and the 8-shaped particles have a particle size of 90 μm.
The particle size of -1t% is 8 to 600 μm.

The particle size of the granular material 80 is 5.5 to 500 μm.

1% of 70 particles has a particle size of 4 to 400 μm.

The granular material 60 weight ratio has a particle size of 2.8 to 350 μm.

The particle size of 50 weight granules is 2.0 to 280 pm.

The grain size of the granular material 4o and qb is 1.6 to 22011 m.

The particle size of the granular material 30 is 1.0 to 180 μm, and the weight range of the granular material 20 is 3 to 160 μm.

The granular material 104i4 has a particle size o of 1 to 125 μm.

Provided is a refractory having a water-soluble salt essentially comprising the water-soluble salt.

According to a preferred embodiment of the present invention, the water-soluble salt has the following particle size distribution y! 1'; KL, there. That is, granules 8 to 11 weight j1% have a particle size of less than 3 μm, and granules 9 to 1%
4% by weight means particle size less than 4μm, 12 to 19% by weight of granules
The particle size is less than 6 μm, and the particle size of 15 to 23 weight f% is 8 μm.
Less than μm, granules 19 to 29 particles have a particle size of less than 11 μm, granules 25 to 36 times, 1 itqb has a particle size of 16 p
Less than m, granular material 31 to 42 t% has a particle size of 22 μm
If the particle size is less than 38 to 50 weight, the particle size is less than 31 μm,
Granular material 44 to 58 weight JJk% has a particle size of less than 44 μm, and granular material 54 to 68 weight JJkqb has a particle size of 6211 m unadjusted 1
65 to 77% of granules have a particle size of less than 88 μm, 75 to 85% of granules have a particle size of less than 125 μm, and 1% of granules have a particle size of less than 125 μm.
The 00 heavy particles each have a particle size of less than 175 μm.

Further, the present invention provides a method for producing castable metal or alloy castings, wherein the particle size distribution of the water-soluble salt is defined as described above, and the method is characterized in that the particle size distribution of the water-soluble salt is defined as described above. Forming a casting M containing a mold and/or core comprised of a formulation comprising a salt, and inserting a charge of a molten castable metal or alloy into a mold assembly comprising this mold. The steps include solidifying the charge and removing the mold and/or core from the formed casting.

Suitable water-bath salts for use in making the core/mold of the present invention include sodium and potassium chloride and sodium metasilicate. Sodium chloride is the preferred salt, and of course # with this salt! It can be used effectively for salmon that are economically interesting. It is of course important to note that the water-bath salt used in certain cases must not melt or decompose at the temperature of use, i.e. the metal casing around which it is cast or formed, should not melt or decompose near the melting point of other materials. and shall be appropriately selected. For example, it is very suitable to use sodium chloride, which has a melting point of 800° C., in aluminum σ), which has a melting point of 660° C. Thus, potassium chloride and sodium metasilicate (melting points of 776°C and 108°C, respectively)
8°C] is also the same.

The core of the present invention comprises preparing a mixture comprising an aqueous salt and a temporary binder, shaping the mixture into a desired shape,
This shaped article is suitably manufactured by firing to remove the binder gold. The mixture may optionally contain other components, such as to enhance the desired properties of the core, such as one or more additional components such as silica, alumina, etc. , zircon, aluminosilicate, talc, magnesia, mullite, ground (may also include sillimanite and sillimanite. This additional component preferably melts at a temperature above 80"C, most preferably %↓ 1000° C. and may be present in the core-forming mixture at up to 100% of the total mixture, most suitably between 2.0 and 2.0° C. at the same temperature. It is good to exist in the 5th category.

The temporary bonding agent used to bond the components of the core-forming mixture to each other during the shaping process and which burns out during firing is known from any of the well-known methods described in the above-mentioned prior art list. It may also be a binder. Accordingly, the binder may be gelatin, resin, polystyrene, or silicone. But eyes? It seems better to use lyethylene glycol. 'f, i.e., σ) with a molecular weight in the range of 4000 to 8000 is preferable;
σ) is most preferred. It is preferable that the binder be present in the amount of σ) in order to arbitrarily supply voids in the packed powder and result in shaping.

It is necessary that the water-bath salt be wetted by the binder. In the case of arrival 1000), what about this σ)? The presence of a wetting agent may be required to ensure this. When the water-soluble salt has a negative charge on its surface, for example in the case of sodium or potassium chloride, the presence of an anionic surfactant is desirable. Suitable surfactants are of the ether sulfate type, among which those considered preferred for use are N.B.M., Chemicals,
Limited [Solumin P
It is sold under the product name EN21JJ. The surfactant is included in the core forming mixture if the mixture is
I: 0.2 to 2. (lii' It is appropriate that it exists as a part of the wealth of Seihan.

The core insert of the present invention consists first of all of a molding material mixture, ie a mixture of aqueous salts, surfactants and other desired ingredients. prepared by preparing and thoroughly mixing these ingredients. Sprinkle the paste into granules.

Then, the next step is to shape the core into the desired shape. Shaping can be carried out by isostatic compression, injection molding, compression molding, transfer molding, extrusion, or casting.

Injection molding is the preferred method, and firing of the shaping core is followed by expulsion of organic material and sintering of the bathable salt granules. It is of course desirable that the degree of shrinkage of the core that occurs during sintering should be kept to a minimum. The inert materials in the core forming mixture then help to prevent this shrinkage.

An essential feature of the present invention is that the granules of aqueous groups used as the main component of the core-forming mixture should have a special and special particle distribution. Yet another feature of the present invention σ) is the means for achieving this particle size distribution. According to the present invention, this is achieved by a non-one-vote semi-wet polishing technique. When sodium chloride, potassium chloride, or sodium chloride is milled using standard ball milling techniques, the particles of the material each have an identical particle size distribution (with a distribution of particle sizes within a very narrow range). , into smaller granules. In the present invention, milling is carried out to give the particle size distribution listed above. One way to achieve this is to transform the salt granules'f!-calendar milling into smaller granules. The method is to obtain each particle having a particle size within the ranges cited above and then to mix the ground granules to produce a granule mixture having a defined particle size distribution. However, according to a feature of the invention, milling of the agglomerates is carried out in a single step by wet grinding the agglomerates in a suitable grinding fluid. The grinding fluid should be non-aqueous, non-polar, and inert to the agglomerate particles, examples of which include ethanol and liquid paraffin. The ball milling method includes the following A parameters:

III Water-bath salts and grinding media (e.g.
ball)? Charge the mill.

(11; Approximately 2 Kg of hydrochloric salt per 1 dm of grinding liquid
be used.

water bath salt approx. I K for un+ mil capacity 5 dm3
Use y.

The grinding proceeds until the grain size distribution of j5r is achieved.

Typical grinding conditions are a ball mill rotation speed of 68 r;
p, m, mill diameter; j6 cm s and milling time 0.5 to 1 hour.

The following examples are given for the purpose of illustrating the invention.
It is.

Example 1 Granular body single size within the range of 50-200 μm (par
Sodium chloride crystals with cels mono 1Iize) Y were wet milled in ethanol.

The grinding conditions were as follows: (item 6) sodium chloride and grinding pole,
1 lll ethanol 1 dm3 to sodium chloride 2 K9.11i1 mil 荏Min 5 dm'' to sodium chloride IKf0 After crushing, the sodium chloride granules were ground to obtain a wet aJ ability, and this was used as a careion surfactant. Specifically, sodium chloride granules were heated to 70°C, and [Solvin PFN21
1J (N.B.M. Chemicals, Limited)
1 bundle width, foil addition T. Next, this mixture was mixed in a twin Z-blade mixer to form an external light component.

The core-forming mixture can be prepared from the following ingredients: di-sodium chloride 70-85%, internal strength 0.5-1.5%, polyethylene glycol (16000 molecules) 12-19 East 1-turn diethylene glycol monostearate 4.8-7.6
Small quantity section, diisooctyl phthalate 1.6~2.7 　'16
The most cruel molding material is di-sodium chloride, 70.75 tons, and surfactant 1.
．． 00% polyethylene glycol (molecule t 6000) 18.
35 tons - 4 units, diethylene glycol monostearate 7.35 units, diisooctyl phthalate 2.55 ttqb.

When preparing the above mixture A, the remaining components are treated with a surfactant, added to sodium chloride, and mixed for about 60 minutes. Paste v made IAIn in this way
Remove from mixer and granulate to sizes suitable for injection molding.

Cores are molded from these granules by conventional injection molding, the temperature of the molding material being approximately 70°C and the mold temperature σ) being approximately 6°C.

The shaped core is removed from the injection mold, placed in a refractory powder (e.g. alumina fine powder) in a refractory box (e.g. saggsr), and heated to 700°C. . Preferably, the rate of temperature rise is less than 40°C/hour up to 200°C and less than 40°C/hour up to 700°C. The number of molded cores is 700.
Bake at ℃ for at least 4 hours.

The shaped cores can be used in the casting of f&'V14& and metal alloys, and the g-molten cores can be subsequently removed from these metals and metal alloys by dissolution in water. OTM casting technologies used include shaiki die-casting,
Pressure die casting, sand casting, investment casting
There are other fire-resistant types of technology available. This core has particular utility in aluminum and aluminum alloy casting, magnesium casting and zinc-based die casting.

Although the invention has been described with particular reference to the casting of metals and metal alloys, the cores of the invention are also useful in the molding of plastics materials using, for example, injection and transfer molding techniques. It should be noted that

Claims (1)

[Claims] 1. A water-soluble salt is contained in the refractory, and the particle size distribution of the water-bathable salt in the refractory is such that the particle size of the granules is from ] to 750 μm, and the 90 weight scale of the granules is Diameter 8-600 μm. 80m1% of the granular material has a particle size of 5.5 to 500/Jm. The particle size of the 70-layer granule is 4 to 400 μm. The grain size of the granular material 60 is 2.8 to 340 μm. Granular material 50 Touhou, grain size 2.0 to 280 μm. The particle size of 40% by weight of granules is 1.6 to 220 pm. The particle size of the granular material 30 weight i is 1.0 to 180 μm. The granular material has a particle size of 0.3 to 160 μm, and the granular material has a particle size of 10% &'! Particle size 0.1-125
A refractory characterized by 74m south. 2. The particle size distribution of the water-bathable salt is within the range specified by the specified fFap requirement, item 1, and molds and/or cores consisting essentially of a formulation comprising this water-bathable salt are used. Shall the mold contain this mold? Introducing a charge of bath-molten castable metal or alloy into a mold assembly, allowing the charge to solidify, and removing the mold and/or core from the formed casting.
A method for producing a castable metal or alloy 8fiI product.