EP0054061B1 - A method of producing frozen casting moulds or cores - Google Patents

A method of producing frozen casting moulds or cores Download PDF

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Publication number
EP0054061B1
EP0054061B1 EP81901923A EP81901923A EP0054061B1 EP 0054061 B1 EP0054061 B1 EP 0054061B1 EP 81901923 A EP81901923 A EP 81901923A EP 81901923 A EP81901923 A EP 81901923A EP 0054061 B1 EP0054061 B1 EP 0054061B1
Authority
EP
European Patent Office
Prior art keywords
binder
mould
frozen
casting moulds
cores
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
EP81901923A
Other languages
German (de)
French (fr)
Other versions
EP0054061A1 (en
Inventor
Emil Jespersen
Bakshi Brijindra Singh
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.)
Dansk Industri Syndikat AS
Original Assignee
Dansk Industri Syndikat AS
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 Dansk Industri Syndikat AS filed Critical Dansk Industri Syndikat AS
Publication of EP0054061A1 publication Critical patent/EP0054061A1/en
Application granted granted Critical
Publication of EP0054061B1 publication Critical patent/EP0054061B1/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B22C9/126—Hardening by freezing

Definitions

  • the invention relates to a method of producing frozen casting moulds or cores of a granular material and a binder in a mould chamber or a core box, comprising the use of a freezable binder which is in a gas or liquid state at positive temperatures calculated in °C.
  • US-A-4 150 704 teaches a method in which the mould sand is admixed with a controlled quantity of water which after moulding is frozen to ice in a certain depth from the surface that is caused to contact molten metal e.g. by placing a layer of so-called dry ice or spraying liquid nitrogen on the surface.
  • the water melts and evaporates so that the mould begins collapsing without the use of mechanical means. Practically no smoke is developed in the casting process, and the mould sand can be reused right away.
  • Freezing of the added water is by nature a rather slow process, and consequently it takes a relatively long time from the moment when the moulding process is finished until the mould has frozen deep enough to be able to resist the effect of molten metal for a sufficiently long time, and this in turn causes the overall mould production to become considerably more time- consuming than the conventional mould manufacturing process.
  • SU-A-428843 it has been proposed to shorten the process time by the application of a hollow pattern, to the cavity of which a cooling medium is continuously supplied.
  • Another proposal set forth in PL-A-21861 1 is to freeze liquid in sand moulds or cores by precooling the pattern or core box in question which is to be engaged by the sand.
  • PL-A-224193 describes the application of a disposable pattern of a permeable material which disintegrates when exposed to the molten metal and through which liquid gas is applied to the mould sand.
  • DE-Al-29 09 839 discloses a mould forming process, in which two streams of sand lead to a mixing device. In one stream water is added to the sand, whereas the sand in the other stream is subjected to a cooling agent such as liquid nitrogen. From the mixing device the mixture of moistened and cooled sand is supplied to the mould box.
  • a still further reduction of the time needed for the production of frozen casting moulds or cores may be obtained by a method in which the binder has been frozen before it is mixed with granular material.
  • the moulding time is substantially reduced to the time it takes to fill the flask or core box with the mixture of and and binder and to compress said mixture sufficiently around the pattern or adjacent the walls of the core box cavity to enable the binder to putty the sand corns together.
  • a mould binder may be used which is present in the form of fine, dendritic particles, e.g. snow, in the mould material, and a compression during the moulding process may entail that the binder obtains part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
  • the mould binder used may, as stated in claim 3, also be present in the form of a finely divided powdered material, e.g. ice, in the mould material, and a compression during the moulding process may entail that the binder obtains part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
  • a finely divided powdered material e.g. ice
  • the snow or the ice When a suitable mixture of granular material and snow or broken ice is compressed in a mould box, the snow or the ice may thus be caused to bind the grains of the material together to impart a cohesive force to the mould or the core sufficient for it to resist the effect from liquid metal which is poured down into the finished mould with or without cores.
  • a corresponding effect can be achieved by injecting one of the mentioned mixtures of mould material into a core box with a sufficiently great force and at a sufficiently great rate.
  • the precooled binder in the form of pulverized material may, as stated in claim 4, also be combined with liquid gas. This permits the temperature of the mould material to be reduced to a very low value before and during the moulding process and during the immediately following casting process.
  • the mixture must be homogeneous and easy flowing.
  • binder there is nothing to prevent the use of conventional setting binders.
  • water glass and liquid carbon dioxide as stated in claim 5, or a mixture of polyisocyanate and phenol resin which is activated by precooled, liquid dimethylethyl amine or triethyl amine, as stated in claim 6. This provides for a reduction in the use of an environmentally harmful binder.
  • the granular material used for the formation of the mould or the core may have been deep frozen in advance in a manner known per se.
  • the process ingredients may have been deep-frozen in advance by means of an admixed freezing agent such as liquid gas.
  • an inert gas obviates any risk of chemical attacks on the equipment used for the process or for chemical reactions with the casting metal.
  • the required cooling may also in a manner known per se be effected or be supported by deep-freezing the parts of the apparatus which the mould material contacts during the moulding process.
  • the pattern board which contacts the same mould surface as the molten metal does later may have been deep-frozen in advance, and a core box deep-frozen in advance may be used in the production of cores.
  • the core box with the core or cores may be cooled simultaneously and additionally, e.g. with liquid gas.
  • a specific embodiment of the method of the invention in the production of casting moulds comprises the use of deep-frozen disposable patterns of a material which evaporates when heated, as stated in claim 7, and this material may expediently have been deep-frozen and foamed, as stated in claim 8.
  • Such patterns may be produced currently in a particular bifurcate pattern mould box corresponding to a conventional core box and be placed in a closed chamber, following which the space between the pattern and the walls of the chamber is filled with the moulding material which is cooled by the pattern and may additionally have been cooled in advance as mentioned above. After the moulding process is finished the pattern evaporates rapidly owing to the heat received. This obviates the inconvenient development of gas, which otherwise takes place in the moulding of disposable patterns.
  • This embodiment of the method results in particularly accurate castings because the inaccuracies which in the conventional mould manfacturing process result from wear on the pattern board caused by shootings of sand, are avoided. Moreover, bifurcation of the mould box is not required when readily evaporable patterns are used.
  • apparatus for the production of casting moulds and/or apparatus for the production of cores are used, the apparatus or parts of it being contained in a cooling chamber.
  • the necessary temperature conditions may be readily and constantly maintained so that valuable production time is not lost in waiting for cooling.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

To produce frozen casting moulds or core boxes the binder is cooled till freezing at least partly before or during the moulding process. This allows the production rate to be increased to such a level that the working rate of automatic machines for the production of casting moulds and core boxes can be turned into full account.

Description

  • The invention relates to a method of producing frozen casting moulds or cores of a granular material and a binder in a mould chamber or a core box, comprising the use of a freezable binder which is in a gas or liquid state at positive temperatures calculated in °C.
  • The specification of US-A-4 150 704 teaches a method in which the mould sand is admixed with a controlled quantity of water which after moulding is frozen to ice in a certain depth from the surface that is caused to contact molten metal e.g. by placing a layer of so-called dry ice or spraying liquid nitrogen on the surface. This gives a very strong mould surface which retains its strength and shape until the surface of the metal has solidified. As the metal gives off its heat, the water melts and evaporates so that the mould begins collapsing without the use of mechanical means. Practically no smoke is developed in the casting process, and the mould sand can be reused right away.
  • An article in the Russian magazine Liteinoe Proizvodsto, 1975, no. 5, p. 21-22, describes the freezing of a sand mould containing 3 to 7% water by means of a coolant that circulates through the evaporator in a cooling system and through the mould.
  • Freezing of the added water is by nature a rather slow process, and consequently it takes a relatively long time from the moment when the moulding process is finished until the mould has frozen deep enough to be able to resist the effect of molten metal for a sufficiently long time, and this in turn causes the overall mould production to become considerably more time- consuming than the conventional mould manufacturing process.
  • In SU-A-428843 it has been proposed to shorten the process time by the application of a hollow pattern, to the cavity of which a cooling medium is continuously supplied. Another proposal set forth in PL-A-21861 1 is to freeze liquid in sand moulds or cores by precooling the pattern or core box in question which is to be engaged by the sand. PL-A-224193 describes the application of a disposable pattern of a permeable material which disintegrates when exposed to the molten metal and through which liquid gas is applied to the mould sand. Furthermore, it has in SU-A-718215 been proposed to mix the moulding sand with solidified carbon dioxide before applying the moulding sand on the pattern, said carbon dioxide serving to cool the moulding sand which contains about 4% water. DE-Al-29 09 839 discloses a mould forming process, in which two streams of sand lead to a mixing device. In one stream water is added to the sand, whereas the sand in the other stream is subjected to a cooling agent such as liquid nitrogen. From the mixing device the mixture of moistened and cooled sand is supplied to the mould box.
  • According to the present invention a still further reduction of the time needed for the production of frozen casting moulds or cores may be obtained by a method in which the binder has been frozen before it is mixed with granular material. Thereby the moulding time is substantially reduced to the time it takes to fill the flask or core box with the mixture of and and binder and to compress said mixture sufficiently around the pattern or adjacent the walls of the core box cavity to enable the binder to putty the sand corns together.
  • As stated in claim 2 a mould binder may be used which is present in the form of fine, dendritic particles, e.g. snow, in the mould material, and a compression during the moulding process may entail that the binder obtains part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
  • The mould binder used may, as stated in claim 3, also be present in the form of a finely divided powdered material, e.g. ice, in the mould material, and a compression during the moulding process may entail that the binder obtains part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
  • When a suitable mixture of granular material and snow or broken ice is compressed in a mould box, the snow or the ice may thus be caused to bind the grains of the material together to impart a cohesive force to the mould or the core sufficient for it to resist the effect from liquid metal which is poured down into the finished mould with or without cores. A corresponding effect can be achieved by injecting one of the mentioned mixtures of mould material into a core box with a sufficiently great force and at a sufficiently great rate.
  • The precooled binder in the form of pulverized material may, as stated in claim 4, also be combined with liquid gas. This permits the temperature of the mould material to be reduced to a very low value before and during the moulding process and during the immediately following casting process. The mixture must be homogeneous and easy flowing.
  • Actually, there is nothing to prevent the use of conventional setting binders. Thus, to form a binder there may be used water glass and liquid carbon dioxide, as stated in claim 5, or a mixture of polyisocyanate and phenol resin which is activated by precooled, liquid dimethylethyl amine or triethyl amine, as stated in claim 6. This provides for a reduction in the use of an environmentally harmful binder.
  • To obtain a better resistance to the heat effect of the molten metal and thereby a delay in the heating of the mould or the core in the casting process, the granular material used for the formation of the mould or the core may have been deep frozen in advance in a manner known per se. Also the process ingredients may have been deep-frozen in advance by means of an admixed freezing agent such as liquid gas. The use of an inert gas obviates any risk of chemical attacks on the equipment used for the process or for chemical reactions with the casting metal.
  • The required cooling may also in a manner known per se be effected or be supported by deep-freezing the parts of the apparatus which the mould material contacts during the moulding process. In the production of casting moulds, particularly the pattern board which contacts the same mould surface as the molten metal does later, may have been deep-frozen in advance, and a core box deep-frozen in advance may be used in the production of cores. Also, the core box with the core or cores may be cooled simultaneously and additionally, e.g. with liquid gas.
  • A specific embodiment of the method of the invention in the production of casting moulds comprises the use of deep-frozen disposable patterns of a material which evaporates when heated, as stated in claim 7, and this material may expediently have been deep-frozen and foamed, as stated in claim 8. Such patterns may be produced currently in a particular bifurcate pattern mould box corresponding to a conventional core box and be placed in a closed chamber, following which the space between the pattern and the walls of the chamber is filled with the moulding material which is cooled by the pattern and may additionally have been cooled in advance as mentioned above. After the moulding process is finished the pattern evaporates rapidly owing to the heat received. This obviates the inconvenient development of gas, which otherwise takes place in the moulding of disposable patterns. This embodiment of the method results in particularly accurate castings because the inaccuracies which in the conventional mould manfacturing process result from wear on the pattern board caused by shootings of sand, are avoided. Moreover, bifurcation of the mould box is not required when readily evaporable patterns are used.
  • As stated in the characterizing portion of claim 9, apparatus for the production of casting moulds and/or apparatus for the production of cores are used, the apparatus or parts of it being contained in a cooling chamber. The necessary temperature conditions may be readily and constantly maintained so that valuable production time is not lost in waiting for cooling.

Claims (9)

1. A method of producing frozen casting moulds or cores of a granular material and a binder in a mould chamber or a core box, comprising the use of a binder which is in a gas or liquid state at positive temperatures calculated in °C, characterized in that the binder has been frozen before it is mixed with the granular material.
2. A method according to claim 1, characterized in that a mould binder is used which is present in the form of fine, dendritic particles e.g. snow, in the mould material, and that compression during the moulding process causes the binder to obtain part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
3. A method according to claim 1, characterized in that a mould binder is used which is present in the form of finely divided powdered material, e.g. ice, in the mould material, and that compression during the moulding process causes the binder to obtain part of or its entire binding capacity depending upon the temperature conditions at the time of the mould manufacturing process.
4. A method according to claim 3, characterized in that the precooled binder in the form of pulverized material is combined with liquid gas.
5. A method according to claim 1, characterized by the use of water glass and liquid carbon dioxide to form a binder.
6. A method according to claim 1, characterized in that a mixture of polyisocyanate and phenol resin which is activated by pre-frozen, liquid dimethylethyl amine or triethyl amine, is used for the formation of a binder.
7. A method according to any of the claims 1-6 in the production of casting moulds, characterized by the use of deep-frozen disposable patterns of a material which evaporates when heated.
8. A method according to claim 7, characterized by the use of disposable patterns manufactured from a deep-frozen, foamed material.
9. A method according to any one of the preceding claims, characterized by the use of apparatus for the production of casting moulds and/or apparatus for the production of cores, the apparatus or parts of it being contained in a cooling chamber.
EP81901923A 1980-06-23 1981-06-22 A method of producing frozen casting moulds or cores Expired EP0054061B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK267580A DK151776C (en) 1980-06-23 1980-06-23 PROCEDURE FOR THE PREPARATION OF FROZEN CASTLE OR CORE
DK2675/80 1980-06-23

Publications (2)

Publication Number Publication Date
EP0054061A1 EP0054061A1 (en) 1982-06-23
EP0054061B1 true EP0054061B1 (en) 1984-10-03

Family

ID=8114515

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81901923A Expired EP0054061B1 (en) 1980-06-23 1981-06-22 A method of producing frozen casting moulds or cores

Country Status (13)

Country Link
EP (1) EP0054061B1 (en)
JP (1) JPH0144424B2 (en)
BE (1) BE889350A (en)
CA (1) CA1183320A (en)
CS (1) CS257755B2 (en)
DD (1) DD159531A5 (en)
DK (1) DK151776C (en)
ES (1) ES8301130A1 (en)
IT (1) IT1136695B (en)
PL (1) PL130506B1 (en)
SU (1) SU1366043A3 (en)
WO (1) WO1982000015A1 (en)
ZA (1) ZA814230B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2681811A1 (en) * 1991-09-27 1993-04-02 Air Liquide PROCESS FOR MANUFACTURING WORKPIECES.
CN113579161B (en) * 2021-07-28 2022-11-01 南京航空航天大学 Large complex freezing sand mold low-temperature forming and over-cold-control cooperative manufacturing method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU428843A1 (en) * 1971-01-04 1974-05-25 METHOD FOR MAKING CASTING FORMS BY FREEZING
US4150704A (en) * 1975-08-14 1979-04-24 W. H. Booth & Co., Ltd. Method of producing sand mounds having a frozen surface
SU718215A1 (en) * 1978-09-21 1980-02-29 Предприятие П/Я А-3470 Method of manufacturing frozen molds
PL218611A1 (en) * 1979-09-27 1981-05-08 Odlewniczych Fab Mas
PL224193A1 (en) * 1980-05-12 1981-11-27 Odlewniczych Fab Mas

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3978906A (en) * 1974-01-29 1976-09-07 Borden, Inc. Process for the rapid production of foundry molds and cores and to a composition for use therein
JPS592575B2 (en) * 1978-06-17 1984-01-19 淳策 中島 Freezing mold manufacturing method and its equipment
JPS5548452A (en) * 1978-09-29 1980-04-07 Ishikawa Chuzosho:Kk Manufacture of mold
PL124538B1 (en) * 1979-02-16 1983-01-31 Inst Odlewnictwa Method of making foundry moulds and cores
DE2909839A1 (en) * 1979-03-13 1980-09-25 Linde Ag Foundry moulds made by freezing moist sand - where sand cooled by liq. nitrogen is mixed with damp sand and driven into moulding box (OE 15.3.80)
DE2912201C2 (en) * 1979-03-28 1987-01-22 Linde Ag, 6200 Wiesbaden Method for producing a casting mold

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU428843A1 (en) * 1971-01-04 1974-05-25 METHOD FOR MAKING CASTING FORMS BY FREEZING
US4150704A (en) * 1975-08-14 1979-04-24 W. H. Booth & Co., Ltd. Method of producing sand mounds having a frozen surface
SU718215A1 (en) * 1978-09-21 1980-02-29 Предприятие П/Я А-3470 Method of manufacturing frozen molds
PL218611A1 (en) * 1979-09-27 1981-05-08 Odlewniczych Fab Mas
PL224193A1 (en) * 1980-05-12 1981-11-27 Odlewniczych Fab Mas

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Liteinoe Proizvodsto" 1975, no. 5, p. 21-22 *
Derwent's abstract no. 74607c/42, published 1980, February 28, Gruzman V.M. *

Also Published As

Publication number Publication date
WO1982000015A1 (en) 1982-01-07
CA1183320A (en) 1985-03-05
CS257755B2 (en) 1988-06-15
DK151776C (en) 1988-08-15
SU1366043A3 (en) 1988-01-07
JPH0144424B2 (en) 1989-09-27
JPS57500819A (en) 1982-05-13
DK267580A (en) 1981-12-24
IT8122460A0 (en) 1981-06-19
ZA814230B (en) 1982-04-28
ES503284A0 (en) 1982-11-16
DD159531A5 (en) 1983-03-16
DK151776B (en) 1988-01-04
BE889350A (en) 1981-12-23
PL231819A1 (en) 1982-02-15
PL130506B1 (en) 1984-08-31
IT1136695B (en) 1986-09-03
ES8301130A1 (en) 1982-11-16
EP0054061A1 (en) 1982-06-23

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