WO2005051567A1 - Composition de moulage - Google Patents

Composition de moulage Download PDF

Info

Publication number
WO2005051567A1
WO2005051567A1 PCT/GB2004/004776 GB2004004776W WO2005051567A1 WO 2005051567 A1 WO2005051567 A1 WO 2005051567A1 GB 2004004776 W GB2004004776 W GB 2004004776W WO 2005051567 A1 WO2005051567 A1 WO 2005051567A1
Authority
WO
WIPO (PCT)
Prior art keywords
moulding composition
composition according
mould
lubricant
pattern
Prior art date
Application number
PCT/GB2004/004776
Other languages
English (en)
Inventor
Richard Kenneth Pearce
Christopher James Moore
David Holme
Original Assignee
Doncasters Limited
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 Doncasters Limited filed Critical Doncasters Limited
Publication of WO2005051567A1 publication Critical patent/WO2005051567A1/fr

Links

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
    • B22C1/14—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 for separating the pattern from the mould
    • 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
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
    • B22C1/181—Cements, oxides or clays

Definitions

  • This invention relates to moulding compositions, and more particularly to a moulding composition and a method of manufacture for the production of a mould for metal casting.
  • gypsum or plaster moulds for the manufacture of intricate, high surface quality metal castings is well-known.
  • aluminium alloy impeller blades for automotive turbochargers, pumps and fans which often have severe undercut portions, can be cast successfully in disposable plaster moulds which are broken after the metal has solidified to extract the casting.
  • Investment casting wherein the mould is manufactured using the lost-wax process, can be employed for casting metal articles in small quantities, but is unsuitable for high volume production of aluminium alloy castings.
  • the pattern for the mould is usually a re-usable, flexible shaped rubber member. A slurry of the plaster in water is poured around the rubber pattern and allowed to dry and harden.
  • the rubber pattern is extracted from the hardened plaster mould to leave a mould cavity of the required shape.
  • intricate designs, such as impeller blades it is often difficult to remove the rubber pattern without damaging either the pattern or the mould. Frequently the fine detail of the internal cavity is disturbed, leaving defects that are not discovered until the metal casting is revealed.
  • a lubricant can facilitate the removal of the pattern from the metal casting mould.
  • the present invention provides a moulding composition for the production of a mould for metal casting from a pattern, wherein the composition comprises an effective amount of a particulate, water- insoluble lubricant, the lubricant being selected such that it does not evolve deleterious quantities of gases or vapours at the casting temperature of the metal.
  • the invention provides a method of manufacture of a mould for metal casting, wherein a slurry of a moulding composition is disposed around a flexible pattern and allowed to harden to produce a mould, which method comprises including in the moulding composition an effective amount of a solid, water-insoluble lubricant such that separation of the pattern from the mould is facilitated.
  • the invention also provides a method of metal casting using a mould produced from a moulding composition and/or by a method of manufacture according to the invention and a cast metal article produced therefrom.
  • the moulding composition is preferably an inorganic composition, although moulding compositions derived from hardenable organic polymeric compounds are not excluded.
  • hardenable organic compounds can include, for example, polyacrylates and glass iono ers, comprising, for example, metal oxides and polyacrylic acid.
  • the moulding composition comprises one or more finely- divided particulate inorganic water-hardenable materials, for example, gypsum, calcined gypsum, plaster of Paris, anhydrous calcium sulphate, wollastonite, cement, lime, other similar plaster-forming materials, and mixtures thereof.
  • the moulding composition can also contain inorganic aggregates and inert fillers, for example, sand, perlite, magnesium oxide and vermiculite; inorganic fibres, for example glass, alumina or boron carbide fibres; and organic fillers, for example, wood particles and fibres.
  • inorganic aggregates and inert fillers for example, sand, perlite, magnesium oxide and vermiculite
  • inorganic fibres for example glass, alumina or boron carbide fibres
  • organic fillers for example, wood particles and fibres.
  • the moulding composition comprises from 70 to 99.9 % by weight calcined gypsum.
  • the moulding composition comprises from 0 to 30 % by weight wollastonite, and 0 to 5 % by weight cement.
  • the moulding composition is preferable one that hardens on contact with water, although other liquids, for example, organic liquids, are not excluded.
  • the moulding composition ⁇ s preferably used in the form of a slurry, which can comprise, for example, a mixture of from 30 to 70 % by weight of particulates .
  • the moulding composition can comprise foaming agents or other pore-forming materials for introducing porosity into the mould.
  • foaming agents or other pore-forming materials for introducing porosity into the mould.
  • Such materials are, however, not always advantageous, and, for example, an improved casting apparatus and method using a relatively impermeable plaster mould is described in our co-pending UK patent application No.039805.6.
  • pore- forming additives are omitted and the resultant mould is relatively impermeable to gases .
  • the water-insoluble lubricant is preferably an inorganic lubricant, since these are less likely to evolve deleterious gases at the pouring temperature of the molten metal.
  • Suitable lubricants include, for example, bentonite, various clays, graphite, boron nitride, molybdenum disulphide and. mixtures thereof.
  • Organic lubricants which could also be used include metal stearates, paraffin or microcrystalline waxes, and higher molecular weight polyethylene glycols . Very good results have been obtained using bentonite, which is the preferred lubricant for the present invention.
  • a particularly preferred moulding composition in accordance with the invention comprises calcined gypsum, cement, inorganic inert fillers and bentonite.
  • the moulding composition comprises from 0.1 to 5% of the lubricant, by weight of solids content, more preferably from 0.5 to 4% by weight, and most preferably from 1 to 3% by weight.
  • the pattern is preferably a shaped, flexible member, more especially a flexible natural or synthetic rubber member.
  • the flexibility of the pattern, together with the presence of the lubricant enables the pattern to be deformed and removed from the hardened mould, even when there are severe undercut regions in the mould cavity.
  • a plaster moulding composition was prepared by mixing 87 % by weight calcined gypsum plaster with 12 % by weight wollastonite and 1 % by weight cement. All percentages are based on the total weight of the composition (without water addition) . Bentonite was then added to the composition as a lubricant, in amounts of 0.5%, 1 %, 2 % and 5 % by weight respectively, based on the total weight of the composition.
  • a flexible rubber pattern in the shape of an impeller blade was placed in an open vessel and the vessel filled with the slurry. After allowing the slurry to dry and harden the rubber pattern was removed to expose the mould cavity.
  • the mould was filled with aluminium alloy in a standard casting method and after quenching a high quality impeller blade was produced. It was found that the presence of the bentonite lubricant made separation of the rubber pattern from the mould much easier than when the lubricant was omitted. In addition, far less finishing work was required on the aluminium casting" .

Abstract

L'invention concerne une composition de moulage à base de matériau particulaire, inorganique et pouvant être durci à l'eau, destinée à la production d'un moule pour fonderie de métaux à partir d'un motif. Cette composition comprend une quantité efficace d'un lubrifiant particulaire, insoluble à l'eau, ce lubrifiant étant choisi de façon à ne pas émettre des quantités délétères de gaz ou de vapeurs à la température de coulée du métal.
PCT/GB2004/004776 2003-11-20 2004-11-10 Composition de moulage WO2005051567A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0326999A GB2408260A (en) 2003-11-20 2003-11-20 Moulding composition including water-insoluble lubricant
GB0326999.0 2003-11-20

Publications (1)

Publication Number Publication Date
WO2005051567A1 true WO2005051567A1 (fr) 2005-06-09

Family

ID=29764128

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2004/004776 WO2005051567A1 (fr) 2003-11-20 2004-11-10 Composition de moulage

Country Status (2)

Country Link
GB (1) GB2408260A (fr)
WO (1) WO2005051567A1 (fr)

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2389539A (en) * 1943-07-23 1945-11-20 Peerpatco Inc Foundry composition
US3007803A (en) * 1958-01-29 1961-11-07 Noble Casting plaster
US3641229A (en) * 1970-07-01 1972-02-08 Research Corp Method of making a permeable ceramic mold used as a substitute for plaster of paris molds
GB1274113A (en) * 1969-09-24 1972-05-10 Tsniitmash A liquid self-hardening mixture for the production of foundry cores and moulds and method for the production thereof
US3743692A (en) * 1972-06-19 1973-07-03 Chemotronics International Inc Method for the removal of refractory porous shapes from mating formed materials
US4081283A (en) * 1976-02-23 1978-03-28 Pmcma Research Group Plaster molding composition
US4541471A (en) * 1983-05-06 1985-09-17 Giulini Chemie Gmbh Process for the production of precision castings by the gypsum-mold process
JPS6268650A (ja) * 1985-09-20 1987-03-28 Toyota Motor Corp 精密鋳造用鋳型材料
JPH04329948A (ja) * 1991-04-30 1992-11-18 Noritake Co Ltd 歯科用埋没材鋳型の焼成方法
FR2845988A1 (fr) * 2002-10-17 2004-04-23 Microcast Melange ceramique a base de platre refractaire et de charges minerales a resistance mecanique amelioree destine a la fonderie de precision par le procede moule-bloc ou un procede derive

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO118158B (fr) * 1965-10-22 1969-11-17 Mitsubishi Heavy Ind Ltd
GB1178363A (en) * 1968-01-24 1970-01-21 Ceskoslovenska Akademie Ved Improvements in or relating to the Manufacture of Moulds for Use in Glass Shaping.
GB1232500A (fr) * 1968-12-23 1971-05-19
CS155928B1 (fr) * 1972-02-15 1974-06-24
US3966479A (en) * 1973-02-27 1976-06-29 Dentsply Research & Development Corporation Dental investment material
GB2062605A (en) * 1979-11-08 1981-05-28 Grinham A Cement composition

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2389539A (en) * 1943-07-23 1945-11-20 Peerpatco Inc Foundry composition
US3007803A (en) * 1958-01-29 1961-11-07 Noble Casting plaster
GB1274113A (en) * 1969-09-24 1972-05-10 Tsniitmash A liquid self-hardening mixture for the production of foundry cores and moulds and method for the production thereof
US3641229A (en) * 1970-07-01 1972-02-08 Research Corp Method of making a permeable ceramic mold used as a substitute for plaster of paris molds
US3743692A (en) * 1972-06-19 1973-07-03 Chemotronics International Inc Method for the removal of refractory porous shapes from mating formed materials
US4081283A (en) * 1976-02-23 1978-03-28 Pmcma Research Group Plaster molding composition
US4541471A (en) * 1983-05-06 1985-09-17 Giulini Chemie Gmbh Process for the production of precision castings by the gypsum-mold process
JPS6268650A (ja) * 1985-09-20 1987-03-28 Toyota Motor Corp 精密鋳造用鋳型材料
JPH04329948A (ja) * 1991-04-30 1992-11-18 Noritake Co Ltd 歯科用埋没材鋳型の焼成方法
FR2845988A1 (fr) * 2002-10-17 2004-04-23 Microcast Melange ceramique a base de platre refractaire et de charges minerales a resistance mecanique amelioree destine a la fonderie de precision par le procede moule-bloc ou un procede derive

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 011, no. 266 (M - 620) 28 August 1987 (1987-08-28) *
PATENT ABSTRACTS OF JAPAN vol. 017, no. 171 (C - 1044) 2 April 1993 (1993-04-02) *

Also Published As

Publication number Publication date
GB2408260A (en) 2005-05-25
GB0326999D0 (en) 2003-12-24

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