US3666706A - Substitute for coal dust in casting molds as lustrous carbon-forming additive - Google Patents

Substitute for coal dust in casting molds as lustrous carbon-forming additive Download PDF

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Publication number
US3666706A
US3666706A US870553A US3666706DA US3666706A US 3666706 A US3666706 A US 3666706A US 870553 A US870553 A US 870553A US 3666706D A US3666706D A US 3666706DA US 3666706 A US3666706 A US 3666706A
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United States
Prior art keywords
composition
percent
plastic material
sand
synthetic plastic
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Expired - Lifetime
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US870553A
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English (en)
Inventor
Winfried Hespers
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RAVENSBERGER EISENHUTTE REINSH
Ravensberger Eisenhutte Reinshagen & Vogt
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RAVENSBERGER EISENHUTTE REINSH
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Filing date
Publication date
Priority claimed from DE19681807453 external-priority patent/DE1807453C/de
Priority claimed from DE19691952357 external-priority patent/DE1952357A1/de
Application filed by RAVENSBERGER EISENHUTTE REINSH filed Critical RAVENSBERGER EISENHUTTE REINSH
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Publication of US3666706A publication Critical patent/US3666706A/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives

Definitions

  • ABSTRACT A non-foamed, unsubstituted hydrocarbon polymer in finely divided form, of particle size less than 0.3 mm in amounts of 0.5 to 3 percent provides the lustrous or glance carbon forming constituent in place of coal dusts in a foundry molding sand composition with 6 to 8 percent bentonite as binder.
  • the aforedescribed carbon-containing additives must be added to the foundry sand in a comparatively great amount, thus amounts of from 5 to percent. Since these are also hygroscopic and thus withdraw water from the foundry sand and from the binder, to compensate therefor the molding composition must have on the whole a comparatively high water content. However, the high water content is again deleterious in the molding composition.
  • a further disadvantage of the carbon-containing additions based upon mineral coals or pitch is that their sulfur content diminishes the binding capacity of the clays, especially bentonite, used as binders, so that a higher amount of binding agent likewise is necessary. This again is disadvantageous, since thereby the gas permeability of the mold composition is diminished.
  • a further disadvantage of the sulfur content of the coal dusts is that subsequent enameling of the casting is made more difficult.
  • Such previously used carbon-containing additives because of the high percentage required in molding sand compositions, could be used only in the production of castings from gray iron or iron alloys with a high carbon content; for in consequence of the carburizing or cementation of the casting, such additives are badly suited to mold compositions intended for preparation of steel casting molds.
  • foam particles to a molding composition does not serve to form the required lustrous carbon layer. Because the synthetic foam particles are present in the form of flocks, they cannot form a coherent lustrous carbon layer, but rather in consequence of their unequal distribution at best only individual specks of lustrous carbon can be formed.
  • the general object of the invention is to provide a substitute for coal dusts as an additive to foundry sand for the formation of lustrous carbon in casting molds and cores, which substitute will not exhibit all of the aforementioned disadvantages of coal dust or other additives, and which in contrast to the hitherto proposed materials is outstanding through other advantageous characteristics and in particular need be added to the molding sand composition in only comparatively small amounts.
  • the present invention proposes as the additive a thermoplastic synthetic plastic in unfoamed form comprised of a non-substituted polymerized hydrocarbon in a particle size of less than 0.5 mm, preferably less than 0.3 mm, and in the molding sand mixture amount to about 0.5 to 3 percent, advantageously a content of 0.5 to 2 percent, by weight.
  • a non-substituted comparatively highly pure hydrocarbon that is, one not including other elements as, for example, bromine, chlorine, sulfur, fluorine or like substances, which exert a harmful influence on the binder for the molding sand, or on the surface of the metal casting to be obtained in the mold.
  • the additive of the invention does not serve as a binder in molding compositions, but merely for formation of lustrous carbon coatings to envelope the quartz grains in the mold.
  • the additive of the invention serves also as a substitute for the coal dust in the so-called black washes which are painted on or sprayed on the casting mold surfaces.
  • the additive here proposed will have a particle size of less than 0.5 mm, it can accordingly be introduced fine slurry as a mold slime material. Accordingly, it represents product obtained in the preparation of non-substituted hydrocarbon polymers by the suspension or emulsion processes, or by the bead polymerization process, without requiring that the polymer be dried or be dried in a high degree as was necessary in its prior processing to a final product. Hence it is not necessary that the water be completely removed from the emulsion polymerizate, or that the latter be rolled out at high temperatures or be compressed or densified through forming in an extrusion press. Rather the extremely finely divided dispersion obtained in the emulsion polymerization can be used as the additive for molding compositions.
  • the starting material in an excess of water with addition of dispersing agents is broken up by powerful stirring into an infinitude of tiny spheres, and in this condition undergoes polymerization.
  • the product plastic needs not to be completely dried as hitherto was the case when carrying out the process for other purposes; but rather the resulting fine spheres can be used wet since, obviously, the molding sand composition must have some water content.
  • the plastic to be used for practice of the invention is to be the product of bead polymerization, then it can be produced with a bentonite content higher than hitherto usual in that process for impeding agglomeration of the individual beads and accordingly can be produced as very fine spheres.
  • the bentonite covering the polymerized beads as a colloidal layer, need not be removed later, since it is also useful in the casting mold as a binder, so that a smaller than otherwise usual additional amount of binding agent, particularly bentonite, has to be added to the molding sand composition.
  • the additive of the invention can be added to the molding composition as a slime material or fine slurry, the addition can be made by a pump wiflt quite exact metering. Also the bead suspension in water can be added to the molding sand.
  • the plastic additive be fine grained or in powder form, so that it can be added to the sand composition as a dry material by means of the metering devices generally present in foundries.
  • the fine grained or powder form can be obtained through milling of a granulate or through spraying or atomizing of a plastic liquified at about 160 to 200C.
  • Particularly advantageous it is in fine grains, with a grain size of 0.2 mm and less, with an average grain size of 0. l 5 mm.
  • the additive has the further advantage that only comparatively small amounts are required in order to form a coherent lustrous carbon layer on the quartz grains of the mold sand. This results because with its even dispersal throughout the sand composition, about 90 percent of the additive is converted into lustrous carbon and the remainder to volatile components, predominately hydrogen. Furthermore, since the plastic additive is not hygroscopic and, moreover, exerts no harmful effect upon the binding capacity of a clay, particularly bentonite, because it is un-substituted and also contains no sulfur, the plastic additive here proposed diminishes the amount of binder required, especially bentonite, and thereby also leads to a smaller water requirement in the sand composition.
  • the additive promotes fluidity of the molding sand composition, it is particularly advantageously suited to sand compositions intended for high pressure molding foundry practice. In these operations, upon pouring of the melt there results no expansion, or only an inconsiderable expansion of the mold space, so that not only are dimensionally exact castings obtained, but also the problems of feed and feeder heads are simplified and under some circumstances absolutely no after-feed needs to follow.
  • the comparatively small amount of additive required does not diminish the gas permeability of the molding sand composition.
  • a molding sand composition with an additive of this invention requires less binder, particularly bentonite, the reprocessing of the molding sand composition is also simpler, because dust removal is not required to so high degree as hitherto with known carbon-containing additives, especially mineral coal dusts.
  • the carbon containing additive in the form of a fine grained synthetic plastic, be pre-mixed with a binding agent especially in the form of sodium bentonite, as an additive composition.
  • lustrous carbon is to be understood as a microcrystalline carbon deposited from the gaseous phase on hot surfaces having a temperature of 650 to 1,000C, said carbon often having a shiny appearance. From a chemical point of view the lustrous carbon is more stable than coke and is only surpassed by graphite. Films of lustrous carbon, of reduced thickness (about lO' mm) fixedly adhere to the base. When the disposition temperature is increased the structure and appearance of the lustrous carbon becomes similar to that of retort graphite.
  • compositions found quite suitable for attaining the abovedescribed advantages for foundry molding and casting operations are represented by the following examples.
  • EXAMPLE 1 In accordance with the invention 10 kg of granulated polystyrene plastic material having an average grain size of 5 mm was ground in a crushing mill to an average grain size of 0.15 mm. Some of the grains had a size of 0.3 mm and others a size of less than 0.15 mm.
  • This fine grained plastic material was fed into a mulling machine of conventional type known under the trade mark Simpson," the said machine being a pan mixer including two heavy wheels rotating on a material receiving pan. 1 ,000 kg of quartz sand having an average grain size of 0.30 mm were received in the mulling machine. 60 kg of Wyoming Bentonite and 40 liters of water were fed into the machine. The mixing operation took place for 3 minutes.
  • the resulting foundry sand composition was then fed into a disintegrator machine of the type known under the trade mark Samon in order to crush the lumps of sand.
  • the sand composition thus containing 90.1 percent sand, 0.9 percent plastic, 5.4 percent bentonite and 3.6 percent water, was fed into a jolt or jar ramming machine of the conventional type, working with usual pressure to obtain a casting mold for machine casting.
  • EXAMPLE 2 12 kg of polyethylene thus representing about 1.1 percent plastic, 5.4 percent bentonite, 3.6 percent water and 89.9 percent sand, instead of 10 kg of polystyrene were used in a second mixture. 5 kg of polypropylene and 5 kg of polystyrene thus representing about 0.9 percent total plastic were used in a third mixture. In each case the grain size was as mentioned in example 1.
  • EXAMPLE 3 1,500 kg of quartz sand having an average grain size of 0.24 mm were fed into the mulling machine as describe above. Thereafter 30 liters of a water-polystyrene emulsion containing 30 percent by weight polystyrene were fed into the mulling machine. The size of the polystyrene particles was less than 0.02 mm. Thereafter 90 kg of sodium bentonite (Wyoming Bentonite) and 40 liters of water were fed into the machine to obtain a water content of 4 percent in the foundry sand.
  • sodium bentonite Woodtonite
  • EXAMPLE 4 69 kg of Wyoming Bentonite were mixed with kg of polystyrene having an average grain size of 0.1 mm. This mixture was introduced into a mulling machine of the type known under the trade mark Simpson together with 1,000 kg of quartz sand having an average grain size of 0. 18 mm. 50 kg of water and 10 kg of com-starch of the type known under the trade mark Maizena-Mogul were introduced during mixing and mixing took place for 5 minutes. The composition thus represented about 87.8 percent sand, 6.06 percent bentonite, 0.88 percent polystyrene, 4.39 percent water, and 0.88 percent starch.
  • EXAMPLE 5 1,000 kg of natural foundry sand of the type known under the trade mark Rosenthal and including glauconite as binding clay were fed into the mulling machine. Thereafter 12 kg of polystyrene having an average grain size of 0.2 mm with greatest particle size of 0.5 mm were fed into the machine. Water was added during the mixing operation to obtain a water content of 6 percent with about 1.1 percent polystyrene in the foundry sand composition. The mixing time was 8 minutes.
  • EXAMPLE 6 80 liters of a water-polystyrene emulsion comprising 40 percent by weight of polystyrene of an average grain size less than 0.02 mm were mixed with 2.5 kg of Wyoming Bentonite and of water to obtain a mold finishing material. This mold finishing material, by weight comprising about 2.4 percent bentonite and about 31 percent polystyrene in water as a carrier, was then painted on the surfaces of a foundry mold of conventional sand composition.
  • EXAMPLE 7 50 liters of a liquid comprising natural resin dissolved in alcohol were mixed with 30 kg of pulverized polystyrene having an average grain size less than 0.1 mm. The resulting composition was sprayed on the surfaces of the mold.
  • the particle size of the plastic material should not be greater than the particle size of the grains of the quartz sand.
  • Coal dust, lignite, peat dust, wood flour can be added to the sand composition according the invention to obtain different effects such as easy break up of the mold after the casting operation.
  • other inorganic substances such as iron oxide can be added in order to avoid casting deficiencies as known per se.
  • all other additions as conventional in preparing foundry sands or core compositions can be added, even if they should produce lustrous carbon to a slight degree.
  • a foundry sand composition consisting essentially of a molding sand, a bentonite binder and water, with all these components in usual contents for molding procedures, and at least 0.5 percent by weight of a lustrous-carbon-forming additive; said additive consisting essentially of a thermoplastic non-foamed polymerized non-substituted hydrocarbon type synthetic plastic material of a particle size smaller than 0.3 mm, said plastic material selected from the group consisting of polystyrene, polyethylene, polypropylene and mixtures thereof.
  • composition as described in claim 1 wherein said synthetic plastic material is comprised of a polystyrene.
  • composition as described in claim 1 wherein said synthetic plastic material is a bead product of bead polymerization.
  • composition as described in claim 1 with said synthetic plastic material added in the form of a water emulmen 5.
  • composition as described in claim 5 wherein the synthetic plastic material amounts to from about 0.5 percent to about 2 percent in the molding sand mixture.
  • composition as described in claim 1 wherein the synthetic plastic material amounts to from about 0.5 percent to about 3 percent in the molding sand mixture.
  • composition as described in claim 1 with said synthetic plastic material added in a fine grained or pulverulant form with size of 0.2 mm and less with an average grain size of 0.15 mm.
  • composition as described in claim 1, wherein said synthetic plastic material has an average particle size smaller than 0.3 mm.
  • a foundry sand mold finishing composition consisting essentially of, by weight, about 2.4 percent bentonite, about 31 percent polystyrene of an average grain size less than 0.02 mm, and the balance water as a carrier; the polystyrene emulsified in water.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Road Paving Structures (AREA)
US870553A 1968-11-07 1969-11-06 Substitute for coal dust in casting molds as lustrous carbon-forming additive Expired - Lifetime US3666706A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19681807453 DE1807453C (de) 1968-11-07 Verwendung von Polymeren des Styrols, Propylene oder Aethylens in Grünsandformmassen
DE19691952357 DE1952357A1 (de) 1969-10-17 1969-10-17 Zusatz fuer Formmassen als Ersatz fuer Kohlenstaeube zur Bildung von Glanzkohlenstoff in Giessformen

Publications (1)

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US3666706A true US3666706A (en) 1972-05-30

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US870553A Expired - Lifetime US3666706A (en) 1968-11-07 1969-11-06 Substitute for coal dust in casting molds as lustrous carbon-forming additive

Country Status (10)

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US (1) US3666706A (en, 2012)
JP (1) JPS4821687B1 (en, 2012)
AT (1) AT298702B (en, 2012)
BE (1) BE741347A (en, 2012)
CH (1) CH551236A (en, 2012)
DK (1) DK129505B (en, 2012)
FR (1) FR2022789A1 (en, 2012)
GB (1) GB1288248A (en, 2012)
NL (1) NL165670C (en, 2012)
SE (1) SE356238B (en, 2012)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4073761A (en) * 1971-08-23 1978-02-14 Hooker Chemicals & Plastics Corp. Polyethylene emulsion containing resin binder compositions and processes
FR2771663A1 (fr) * 1997-12-03 1999-06-04 Manfred Buchler Composition fluide capable de produire du carbone brillant au cours de la coulee du metal et son procede de preparation
US20100224755A1 (en) * 2007-05-02 2010-09-09 Ashland-Südchemie-Kernfest GmbH Coating compounds for casting moulds and cores that prevent reaction gas defects
CN102909314A (zh) * 2012-09-29 2013-02-06 温州市康霸洁具有限公司 一种树脂砂

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE413997B (sv) * 1977-01-17 1980-07-07 Westin & Backlund Ab Sett vid framstellning av gjutformar eller gjutkernor ur en vattenhaltig blandning av formsand, bindemedel och kolhaltigt material, som kan bilda sa kallad glanskol, samt formmassa avedd att anvendas vid settet
DE3305745C2 (de) * 1983-02-17 1987-01-08 Hüttenes-Albertus Chemische Werke GmbH, 4000 Düsseldorf Verfahren zur Herstellung eines Glanzkohlebildners für Gießereizwecke

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2857355A (en) * 1953-10-27 1958-10-21 Du Pont Polyethylene-estersil composition
US2988525A (en) * 1957-07-09 1961-06-13 American Colloid Co Foundry mold composition
US3005244A (en) * 1958-06-09 1961-10-24 Howe Sound Co Production of shell molds
US3467165A (en) * 1965-10-22 1969-09-16 Georgi S Angeloff Method of making foundry molds

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2857355A (en) * 1953-10-27 1958-10-21 Du Pont Polyethylene-estersil composition
US2988525A (en) * 1957-07-09 1961-06-13 American Colloid Co Foundry mold composition
US3005244A (en) * 1958-06-09 1961-10-24 Howe Sound Co Production of shell molds
US3467165A (en) * 1965-10-22 1969-09-16 Georgi S Angeloff Method of making foundry molds

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4073761A (en) * 1971-08-23 1978-02-14 Hooker Chemicals & Plastics Corp. Polyethylene emulsion containing resin binder compositions and processes
FR2771663A1 (fr) * 1997-12-03 1999-06-04 Manfred Buchler Composition fluide capable de produire du carbone brillant au cours de la coulee du metal et son procede de preparation
WO1999028064A1 (fr) * 1997-12-03 1999-06-10 Huttenes Albertus France (S.A.R.L.) Composition fluide capable de produire du carbone brillant au cours de la coulee du metal et son procede de preparation
US6506817B1 (en) 1997-12-03 2003-01-14 Huttenes-Albertus France S.A.R.L. Fluid composition for forming lustrous carbon during metal casting and process for its preparation
US20100224755A1 (en) * 2007-05-02 2010-09-09 Ashland-Südchemie-Kernfest GmbH Coating compounds for casting moulds and cores that prevent reaction gas defects
CN102909314A (zh) * 2012-09-29 2013-02-06 温州市康霸洁具有限公司 一种树脂砂

Also Published As

Publication number Publication date
AT298702B (de) 1972-04-15
GB1288248A (en, 2012) 1972-09-06
NL165670C (nl) 1981-05-15
CH551236A (de) 1974-07-15
SE356238B (en, 2012) 1973-05-21
BE741347A (en, 2012) 1970-04-16
DK129505C (en, 2012) 1975-03-17
NL165670B (nl) 1980-12-15
NL6916249A (en, 2012) 1970-05-11
DK129505B (da) 1974-10-21
JPS4821687B1 (en, 2012) 1973-06-30
FR2022789A1 (en, 2012) 1970-08-07

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