JPS61186145A - Casting master die - Google Patents

Abstract

PURPOSE:To shape repeatedly a sand mold, large in resistance to wear, easily separable from molding sand and excellent in surface accuracy, by forming a compound, consisting essentially of cements material, ultra fine powder, high- performance dehydrating agent, water and aggregates, into a casting master die of desired shape. CONSTITUTION:As the cements material, normal Portland cement, high-early- strength or super high-early-strength, or white Portland cement, and sulfate- resistant Portland cement, etc. are used. Next, the ultrafine powder means that its average particle size is smaller, by one unit lower at least, than that of said cement material; and silicon, an alloy containing silica, silica dust or siliceous dust are most suitable. Further, as the high-performance dehydrating agent, a material consisting essentially of a salt of naphthalenesulfonic acid- formaldehyde condensate and a salt of melaminesulfonic acid-formaldehyde condensate, etc. is used. next, as an aggregate, silica rock, emery, iron pyrite, magnetite, topaz, lawsonite, corundum, phenacite, etc. are used. Further, the quantity of water is made as small as possible.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method of forming a composition containing a cementitious material, an ultrafine powder, a high performance water reducing agent, water and an aggregate into a desired shape into a desired shape. The invention relates to a MvlJ master mold for forming sand molds in the production of cast metal products.

[Conventional technology]

Conventionally, metals, resins, rubber, plaster, and cement have been used as casting master molds because they are robust (high strength), produce precision products, are inexpensive, and have short manufacturing times. Ta.

However, although metal molds are superior in robustness and precision, they have the drawbacks that they are expensive in material and processing costs, take time to produce, and require skill in processing. On the other hand, resin and rubber gardens require a short manufacturing period, but their abrasion resistance against sand is opaque, and their electrical resistance is high, so when the sand mold is released, an electrostatic attraction is generated, causing the mold to interact with the sand. Not only is there a problem with repeated use, but the surface layer of the sand mold has poor precision, and the mold odor from plaster and cement is also low, and its strength is low and it has poor abrasion resistance against sand. It had almost the same drawbacks as resin or rubber molds, due to insufficient properties.

[Intermediate point that the invention attempts to solve]

The present inventors have discovered that regarding the inexpensive cement-based master
As a result of extensive research to solve the above drawbacks, we found that a mortar made by adding ultrafine powder and a high-performance water reducer to cement and mixing it with the required amount of aggregate and a small amount of water has extremely good fluidity. The present inventors have found that the cured product has sufficient robustness as a master mold, and has completed the present invention.

[Means for resolving intermediate points]

That is, the present invention is a casting master mold, which is characterized by molding a mixture whose main components are a cementitious material, ultrafine powder, a high-performance water reducing agent, water, and aggregate into a desired shape and heating it at ℃.

The present invention will be explained in more detail below.

The cementitious material used in the present invention generally includes ordinary Portland cement, early-strength, ultra-early-strength or white Portland cement, #sulfur fR salt Portland cement, and mixed cements such as slag and fly ash. However, the general curing method for parent cement is not favorable in terms of stability as the reaction continues for a long period of time, so when using it, high temperature curing etc. are required to accelerate the reaction. Consideration must be given to using them together.

In addition, it is not possible to compensate for shrinkage using expansive cement, to develop the required strength in a short period of time with rapid hardening cement, or to use gypsum-based high-strength admixtures.

As the expanding component of the expanding cement, ettringite-based materials such as "csA#20J" manufactured by Denki Kagaku Kogyo Co., Ltd. and calcined CaO are preferable, and among the calcined CaO, 1100 to 13
Particularly preferred are those which are fired at 00°C and have an average crystal diameter of 10μ or less.

The rapid hardening cement contains a calcium aluminate-based rapid hardening component, such as calcium aluminate alone or a mixture of calcium aluminate and calcium sulfate, etc.
It has the product name ``Denka X8J'
There are cements containing 4F and the product name ``Jet Cement'' manufactured by Onoda Cement ■.

°The high-strength admixtures are gypsum-based. "Crepe" is available.

The ultrafine powder used in the present invention has an average particle size smaller than that of the above-mentioned cementitious material (one order of magnitude lower in both cases, and in particular, one with an average particle diameter of two orders of magnitude lower is preferable from the viewpoint of flow characteristics of the mixed material. Specifically, silica dust (silica fume) and siliceous dust, which are produced as by-products during the production of silicon, silicon-containing alloys, and zirconia, are particularly suitable.In addition, calcium carbonate, silica glue, opalescent silica, and fly ash are particularly suitable. , slag, titanium oxide,
Ultrafine powders such as aluminum oxide can also be used. In particular, the use of ultrafine powder obtained by pulverizing opalescent silica, fly ash, and slag using a jet mill equipped with a classifier is effective in improving curing shrinkage.

The amount of ultrafine powder used is preferably 5 to 40 parts by weight per 60 to 95 parts by weight of the cementitious material, more preferably 10 to 35 parts by weight per 65 to 90 parts by weight, 5
If it is less than 40 parts by weight, it is impossible to obtain high strength (fastness), and if it exceeds 40 parts by weight, the fluidity of the kneaded product will decrease significantly, making it difficult to mold, and the strength will not be developed. It will be enough.

The high-performance water reducing agent used in the present invention is a surfactant with a large dispersion ability that does not cause too much delay in setting or excessive air entrainment even when added to cement in large quantities, and is a surfactant that has a high dispersion ability and does not cause excessive setback delay or excessive air entrainment even when added to cement in large quantities. Examples include salts, melamine sulfonic acid formaldehyde FM metal salts, high molecular weight lignin sulfonates, polycarboxylate salts, etc. as main components. High-performance water reducing agents are necessary to obtain mixed materials at a low water ratio, and conventionally the amount used is 0.3 to 11 t% as a solid content based on cementitious materials, but this In the invention, it is preferable to add it in a larger amount. Specifically, the mixture of cementitious material and M1 fine powder is used as a solid content up to about 10 parts per 100 parts, and if it is added in a larger amount, it will adversely affect the hardening reaction. A particularly preferable addition amount is 1 to
It is a five-layered site. When such a high performance water reducing agent is used in an amount of 5, in combination with ultrafine powder, a fluid mixed material that can be molded by a conventional method can be obtained even if the water weight ratio is 25% or less.

The aggregate used in the present invention may be one that has been conventionally used in the preparation of general concrete ya1', but it may be harder, specifically, one with a Mohs hardness of 6 or more, preferably 7 or more, or Knoop It is preferable to use an indenter having an indenter hardness of at least 700 degrees/tomo 2, more preferably at least 800 degrees/tomo, since the strength can be significantly improved. Examples of materials that meet this standard are silica, emery, 'iIC, magnetite, yellow jade, lawsonite, corundum, 7-enercite, spinel, beryl, gold-cut stone, tourmaline, granite, andalusite, and cross stone. ,
Examples include zircon, calcined bauxite, carbide cords, tungsten carbide, 7-erosilicon nitride, fused silicon, bath-fused silica, fused magnesia, silicon carbide, and crystalline borosilicate. The amount of aggregate to be used is usually selected to be within 5 times the weight of the total of the cement a substance and the ultrafine powder.

The water used when preparing the mixture in the present invention is necessary for molding, but in order to obtain a high-strength casting master mold, it is better to use as high a current as possible (i.e., cementitious material and ultrafine powder). It is recommended that the amount of water be 12.5 to 30 parts by weight (particularly 15 to 28 parts by weight) per 100 parts by weight of the mixture.If the amount of water is more than 60 parts by weight, it will be difficult to obtain a high-strength casting master mold. If the amount is less than 12.5 parts by weight, it will be difficult to perform normal molding such as pouring.However, in consolidation molding, etc., there is no limitation to this, and molding can be performed even if the amount is less than 12.5 parts by weight. becomes.

In addition to the above-mentioned combinations, it is also effective to combine various fibers 7 in order to improve the bending strength and crack resistance of the casting master mold. Fibers include steel fibers, stainless steel fibers, natural and synthetic mineral fibers such as asbestos and alumina fibers, carbon fibers, glass fibers, and natural or synthetic fibers such as polypropylene, vinylon, acrylonitrile, and cellulose. can give. In addition, in case of large size, reinforcing reinforcing bars are used.

The above-mentioned materials may be mixed and kneaded by any method as long as they can be mixed and kneaded uniformly, and the order of addition is not particularly limited.

When molding the casting master mold of the present invention, care should be taken to prevent the formation of air bubbles on the casting surface of the mold, and methods such as vacuum injection after Makabe kneading or degassing before molding can be used to prevent air bubbles. It is preferable to remove it.

In addition, when casting a casting master mold using the above-mentioned material according to the present invention, only the surface in contact with sand is molded with the material according to the present invention, and the remaining part is made of ordinary cement-based or plaster. It can also be molded from other materials.

As a curing method, any of the following methods can be adopted: room temperature curing, normal pressure steam curing, high temperature and high pressure curing, and high temperature curing.
If necessary, perform a combination of these treatments.

The present invention will be specifically explained below using Examples.

[Example] The figure shows a series of steps when manufacturing a special rotating blade using @iron (re-25).

First, is the wooden archetype 1 for engineers? : Manufacture, apply it, and inject the cement mixture 4 according to the present invention (Step C)
). The cement mixture was made using the following materials, mixed together in a vacuum omnimixer, then vacuum cast and vibratory compacted. The curing was steam curing for 80'0.7 hours, and according to a separately molded 4 x 4 x 16 specimen, the temperature was 1450 to 9/ctr? This indicates the compressive strength of That's all 5
The master mold 4' obtained in step 4 was sanded and compacted using furan resin as a binder (Step D), and bath water was poured into the sand mold 5' to produce a rotary blade (Step E).

Materials used: Q White Portland Cement (manufactured by Chichibu Cement Co., Ltd.) 76
0 parts by weight silica hume (manufactured by Japan Heavy Chemical Industry Co., Ltd.) 16 parts by weight 0 expansion agent (rcsA20RJ by Denki Kagaku Kogyo Co., Ltd.) 8 parts by weight 0 high performance water reducing agent (Denki Kagaku Kogyo Co., Ltd. (Zeri l'-FT-50)
[]J) (Active ingredient) 2 parts by weight.

0 aggregate (Emery (manufactured by Sumitomo Metal Mining)) 0.6 to 1.2, 1.5 to 2,5, 50 parts by weight each, 0 water, 20 parts by weight.

1,000 rotary blades were manufactured by repeating processes aD and E, but all of the master molds were found to have no abnormalities, the sand mold was released perfectly, and the surface roughness of the product was sufficient.

For comparison, the master mold was prepared using gypsum, resin, rubber, or ordinary cement (100 parts of white Portland cement, 0.5 parts of high-performance water reagent, 100 parts of violet aggregate, and 60 parts of water).
0 liter amount), and using it, ``C rotary blade polishing (
Song. The results are shown in the table.

〔Effect of the invention〕

The casting master mold of the present invention has high strength (high wear resistance).
Since the resistance is low (good sand release resistance), products with good surface accuracy can be produced and used many times, making it especially useful for MB4-related industries with short product cycles.

[Brief explanation of drawings]

The drawings are diagrams illustrating the steps from making a wooden mold to casting.

Claims (1)

[Claims] A casting master mold characterized by being made by molding a mixture whose main components are cementitious material, ultrafine powder, high-performance water reducing agent, water, and aggregate into a desired shape.