EP0030940B1 - Production of metal castings - Google Patents

Production of metal castings Download PDF

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Publication number
EP0030940B1
EP0030940B1 EP80900667A EP80900667A EP0030940B1 EP 0030940 B1 EP0030940 B1 EP 0030940B1 EP 80900667 A EP80900667 A EP 80900667A EP 80900667 A EP80900667 A EP 80900667A EP 0030940 B1 EP0030940 B1 EP 0030940B1
Authority
EP
European Patent Office
Prior art keywords
composition
aluminium
pads
mould
casting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP80900667A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0030940A1 (en
Inventor
Michael John Gough
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Foseco International Ltd
Original Assignee
Foseco International Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Foseco International Ltd filed Critical Foseco International Ltd
Publication of EP0030940A1 publication Critical patent/EP0030940A1/en
Application granted granted Critical
Publication of EP0030940B1 publication Critical patent/EP0030940B1/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D7/00—Casting ingots, e.g. from ferrous metals
    • B22D7/06—Ingot moulds or their manufacture
    • B22D7/10—Hot tops therefor
    • B22D7/104—Hot tops therefor from exothermic material only

Definitions

  • This invention relates to the production of metal castings, particularly steel castings, in sand or like moulds.
  • the metal contained in the feeder solidifies at least at the same time or preferably after the last part of the casting to solidify and that there is a path for liquid metal from the feeder to all parts of the casting to compensate for the shrinkage contraction which occurs when liquid metals or alloys solidify. It is therefore, a requirement of sound castings production to promote progressive directional solidification from the point most remote from the feeder towards the feeder so that the feeder is the last section of the casting to solidify. Unfortunately, the required shape of many castings is such that without change to the design, directional solidification cannot be achieved.
  • the desired shape of many steel castings has to be altered in order to provide feed metal to those parts of the casting which are remote from feeder heads.
  • the alteration generally takes the form of thickening up the metal at those casting sections where premature solidification would otherwise occur and thereby cause shrinkage cavities in isolated hot spots.
  • This alteration in casting shape by the addition of extra metal is known as metal padding.
  • Typical of the types of casting which must be padded with metal in order to obviate internal shrinkage are gear wheel blanks, valve bodies and bonnets, H-arm wheels, idler wheels, pistons, rolls and turbine casings.
  • gear wheel blanks In the basic shape of these and other castings there are heavy sections which are isolated from sources of feed metal. Metal pads are therefore positioned in such a way that they promote directional solidification throughout the casting.
  • the added metal padding must be removed after the casting and feeder have solidified.
  • the removal of the metal pad can involve one or more of the following operations: flame cutting, sawing, grinding and machining. These are lengthy and expensive processes and often create bottlenecks in foundry production. Padding removal therefore is uneconomic in itself and metal padding involves melting additional quantities of metal to that required for the metal castings themselves.
  • Alumino-thermic compositions which have been used for this purpose are well known and are described for example in British Patent Specification Nos. 971 749 and 808 400. They generally consist of finely divided aluminium, one or more oxidising agents for the aluminium such as an alkali metal or alkaline earth metal nitrate or perchlorate, iron oxide or manganese oxide, a fluoride such as calcium fluoride or sodium aluminium fluoride to initiate and control the exothermic reaction, one or more particulate refractory fillers such as sand, alumina, grog, chamotte or other refractory silicate known per se, and one or more binders such as starch, dextrin, sulphite lye, gum arabic, resins such as phenol formaldehyde resin, sodium silicate and clays.
  • the quantity of oxidising agent is usually stoichiometrically insufficient to oxidise all the aluminium present.
  • pads of such exothermic compositions if correctly applied promote progressive directional solidification, their use in its turn produces new problems. Due to the exothermic reaction, gases are evolved from the exothermic composition and these must be vented to the atmosphere outside the mould to avoid casting defects such as blow holes or pinhole porosity. Sometimes, because of the location of the exothermic pad in the mould it is difficult if not impossible to find a path from the pad to the atmosphere for the escape of gases evolved during the exothermic reaction.
  • Such materials generally comprise a refractory mineral fibre of, for example, alumino-silicate or calcium silicate, a particulate refractory filler as previously described and a binder system such as colloidal oxide hydrosols and/or starch and/or phenol formaldehyde resin.
  • a refractory mineral fibre of, for example, alumino-silicate or calcium silicate, a particulate refractory filler as previously described and a binder system such as colloidal oxide hydrosols and/or starch and/or phenol formaldehyde resin.
  • a process for the casting of molten metal in a sand or like mould in which there are provided at one or more locations in the mould where it is desirable to promote progressive directional solidification, lining pads located either to constitute or to support the metal contacting surface of the sand mould and to provide with the remainder of the sand mould a cavity of the desired shape and dimensions, the pads being formed of a composition comprising particulate refractory material, finely divided aluminium, an oxidising agent for the aluminium and a binder, characterised in that the composition is substantially free of fluoride salts and contains a fibrous refractory material known per se and the pads have a density of 0.3 to 1.1 g/cm3.
  • a padding composition comprising particulate refractory material, finely divided aluminium, an oxidising agent for the aluminium and a binder is applied to those portions of a pattern at which it is desired to promote progressive directional solidification in a casting of the shape of the pattern, moulding sand is applied around the pattern and the composition, the composition is hardened to produce pads, and the resulting mould and pads are stripped from the pattern, characterised in that the composition is substantially free of fluoride salts and contains a fibrous refractory material known per se and the pads have a density of 0.3 to 1.1 g/cm 3 .
  • a padding material comprising particulate refractory material, finely divided aluminium, an oxidising agent for the aluminium and a binder, for promoting progressive directional solidification in a metal casting, characterised in that the material is substantially free of fluoride salts, contains a fibrous refractory material known per se and has a density in the range of 0.3 to 1.1 g/cm3.
  • the pads may be preformed and dried before being located in a mould or next to a pattern or they may be produced from a composition in the form of a flexible mat which can be placed in position in a mould or around a pattern or in the form of a mouldable mixture which can be rammed into position around a pattern or into a cavity in a mould.
  • the flexible mat or the mouldable mixture may be dried by the action of heat or hardened by chemical means.
  • a flexible mat or mouldable mixture which can be hardened chemically is preferred.
  • Suitable fibrous refractory materials include alumina fibres, alumino-silicate fibres and calcium silicate fibres such as slag wool, rock wool or mineral wool.
  • Suitable particulate refractory materials include alumina, mullite, sillimanite, chamotte, grog, calcined fireclay, calcined flint clay, silica expanded vermiculite, expanded perlite, calcined rice husks and crushed coke. It is important that the particulate refractory material contains no more than traces of fluoride salts otherwise metal castings produced using the pads are likely to be contaminated with aluminium.
  • Suitable oxidising agents include alkali metal nitrates, alkaline earth metal nitrates, alkali metal perchlorates, iron oxide and manganese oxide.
  • Suitable binders include organic binders such as resins dextrin, starch, sulphite lye, gum arabic and/or inorganic binders such as alkali metal silicates, colloidal oxide hydrosols and clays such as kaolin clays or ball clays.
  • the composition may also contain a small proportion of organic fibre, such as rayon fibre, particularly when the composition is to be used in the form of a flexible mat.
  • the preferred pad compositions are (percentages by weight):-
  • the density of the pads is as low as possible and in practice pads having a density of 0.3-1.1 glcni3 are satisfactory. Within this range the optimum density for a particular material will depend on the composition of the material because with most compositions refractoriness also decreases as density decreases.
  • the pads according to the invention may be manufactured and used in one of a number of ways.
  • the individual ingredients may be mixed in one of a number of suitable mixing machines and moistened with water until a rammable consistency is achieved.
  • the mixture may than be rammed into a cavity in a sand mould or core or laid against a casting pattern or compacted in a core box and hardened chemically or dried by the application of heat in, for example, an oven or by gentle application of a gas flame.
  • the ingredients may be mixed with water into a slurry which is then dewatered by connecting to vacuum a suitable shape mesh former immersed in the slurry in order to produce the required shape, in general as taught by British Patent Specification No. 1 204 742. It may be desirable to include a dispersion agent such as aluminium sulphate to aid in the dispersion of the ingredients in the slurry.
  • the green shape may be dried in, for example, an oven or hardened chemically either separately or as an integral part of a core or mould. Pads made by the manufacturing method described, have a density when dried in the range 0.3 to 1.1 g/cm 3 and usually in the range 0.45 to 0.95 g/cm 3 .
  • the preferred method is to apply an alkaline substance to a few points on the surface of the mat or moulded mixture as described in British Patents 775 380 and 808 400.
  • Suitable alkaline materials include hydroxides, carbonates and aluminates of alkali metals such as sodium and the materials are preferably applied to the pads as aqueous solutions.
  • a water-soluble nitrate such as an alkali metal nitrate is essential.
  • the alkali metal nitrate may be dissolved in the aqueous solution of the alkaline material or included in the composition of the flexible mat or mouldable mixture as at least a proportion of the oxidising agent present in the composition.
  • the casting 1 produced using the pad 9 was sound and was not contaminated by aluminium.
  • Figure 5 illustrates the use of a pad formed from a mouldable mixture according to the invention.
  • a composition was produced as follows:
  • the composition of the alkaline solution was:
  • the density of each of the pads was recorded and casting soundness and aluminium pick-up in the casting face in contact with the pad were determined.
  • the pad according to the invention made from composition 3 was sufficiently exothermic even in the absence of fluoride and had sufficiently good heat insulation properties to produce a sound casting and did not cause the casting to pick up aluminium.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
EP80900667A 1979-06-14 1980-12-30 Production of metal castings Expired EP0030940B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7920757 1979-06-14
GB7920757 1979-06-14

Publications (2)

Publication Number Publication Date
EP0030940A1 EP0030940A1 (en) 1981-07-01
EP0030940B1 true EP0030940B1 (en) 1984-01-11

Family

ID=10505851

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80900667A Expired EP0030940B1 (en) 1979-06-14 1980-12-30 Production of metal castings

Country Status (10)

Country Link
EP (1) EP0030940B1 (OSRAM)
JP (1) JPS56500681A (OSRAM)
KR (1) KR840000602B1 (OSRAM)
BR (1) BR8008710A (OSRAM)
CA (1) CA1128255A (OSRAM)
ES (1) ES492411A0 (OSRAM)
GB (1) GB2063126B (OSRAM)
IT (1) IT8067928A0 (OSRAM)
WO (1) WO1980002811A1 (OSRAM)
ZA (1) ZA802394B (OSRAM)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19953402A1 (de) * 1999-11-06 2001-05-10 Wagner Heinrich Sinto Masch Verfahren und Vorrichtung zum Herstellen und Abgießen einer aus zwei Formhälften bestehenden Gießform

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3122597C2 (de) * 1981-06-06 1987-04-30 Mannesmann Rexroth GmbH, 8770 Lohr Speisermodell für ein Gußstück
GB9522741D0 (en) * 1995-11-07 1996-01-10 Firth Vickers Centrispinning L Making a metal shape by casting
GB9618216D0 (en) * 1996-08-30 1996-10-09 Triplex Lloyd Plc Method of making fine grained castings
US6298900B1 (en) 1998-07-06 2001-10-09 Ford Global Technologies, Inc. Method of integrating wear plates into a spray formed rapid tool
DE19920570B4 (de) * 1999-05-04 2008-01-10 Chemex Gmbh Formbare exotherme Zusammensetzungen und Speiser daraus
DE19925167A1 (de) * 1999-06-01 2000-12-14 Luengen Gmbh & Co Kg As Exotherme Speisermasse
US9180511B2 (en) 2012-04-12 2015-11-10 Rel, Inc. Thermal isolation for casting articles
JP5347077B1 (ja) * 2013-03-19 2013-11-20 テクノメタル株式会社 砂型鋳造方法
RU2691826C1 (ru) * 2018-03-26 2019-06-18 Федеральное государственное автономное образовательное учреждение высшего образования "Национальный исследовательский Томский государственный университет" (НИ ТГУ) Способ получения отливок из дисперсно-упрочненных сплавов на основе алюминия или магния
AU2022256785A1 (en) * 2021-04-16 2023-10-26 Foseco International Limited Refractory article and composition

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1084449B (de) * 1953-08-05 1960-06-30 Fachanstalt Fuer Giessereiwese Waermeentwickelnde, form- und haertbare Masse fuer Steiger und Trichter von Giessformen und fuer Blockkoepfe
GB769719A (en) * 1954-01-26 1957-03-13 Georges Lemoine Improvements in or relating to exothermic mixtures
GB880868A (en) * 1958-11-28 1961-10-25 Foundry Services Int Ltd Improvements in or relating to heat producing compositions
US3025153A (en) * 1959-01-21 1962-03-13 Foundry Services Int Ltd Heat-producing mixtures

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19953402A1 (de) * 1999-11-06 2001-05-10 Wagner Heinrich Sinto Masch Verfahren und Vorrichtung zum Herstellen und Abgießen einer aus zwei Formhälften bestehenden Gießform

Also Published As

Publication number Publication date
WO1980002811A1 (en) 1980-12-24
KR840000602B1 (ko) 1984-04-28
CA1128255A (en) 1982-07-27
KR830002549A (ko) 1983-05-30
GB2063126B (en) 1983-01-26
IT8067928A0 (it) 1980-06-13
BR8008710A (pt) 1981-04-28
ZA802394B (en) 1981-04-29
ES8101943A1 (es) 1980-12-16
GB2063126A (en) 1981-06-03
JPS56500681A (OSRAM) 1981-05-21
ES492411A0 (es) 1980-12-16
EP0030940A1 (en) 1981-07-01

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