US2877523A - Vacuum casting - Google Patents

Vacuum casting Download PDF

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Publication number
US2877523A
US2877523A US531028A US53102855A US2877523A US 2877523 A US2877523 A US 2877523A US 531028 A US531028 A US 531028A US 53102855 A US53102855 A US 53102855A US 2877523 A US2877523 A US 2877523A
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US
United States
Prior art keywords
container
mould
casting
accumulator
vacuum
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 - Lifetime
Application number
US531028A
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English (en)
Inventor
Turnbull John Stratton
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.)
Metropolitan Vickers Electrical Co Ltd
Original Assignee
Metropolitan Vickers Electrical Co 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 Metropolitan Vickers Electrical Co Ltd filed Critical Metropolitan Vickers Electrical Co Ltd
Application granted granted Critical
Publication of US2877523A publication Critical patent/US2877523A/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/06—Vacuum casting, i.e. making use of vacuum to fill the mould

Definitions

  • This invention relates to vacuum casting, that is to say, to methods of casting wherein the mould issubjected to suction or evacuation to a desired degree during the pouring of the metal or other material to be cast.
  • the present invention has for its object to provide a method of vacuum casting wherein the disadvantages set forth above ymay be obviated.
  • the invention is eminently, but not exclusively, applicable to the so-called precision casting.
  • the methodof-.vacuumcasting according-tov the present invention comprises supporting a permeable shell mould within a container by means of permeable -supporting means between the outer surface of the shell and the inner surface of the container, connecting the container with a vacuum accumulator and evacuating pump with valve means between the container and the accumulator, evacuating the accumulator with thevalve means closed, and subsequent to said evacuationV of the accumulator; opening said valve means and pouringv the metal or other casting material into the mould as a combined operation, that is to say, more or less simultaneously.
  • the supporting means referred to preferably comprises packed granular material of angular form and of large size,k such as hereinafter indicated.
  • the compositev materialformed by the shell and the supporting means is designed for maximumr or high flow of air or gas. from the mould'cavity or cavities within the shell directly from the inner surface of each cavity through the permeable wall of the shell. Since a permeable shell mould is employed, that is to say, a mould which has an outer shape conforming substantially to the general shape of the mould cavity, or cavities in the case of a complex casting, the arrangement is therefore such that the air or gas can pass freely through the shell wall on all or substantially all surfaces of the mould cavity or cavities.
  • the accumulator Since the accumulator is evacuated prior to the casting operation and with the valve means closed, a comparatively small evacuating pump is enabled rapidly to evacuate ICC 2., the. mould cavity or cavities of air or gas, it beingdmderstood. that. the accumulator has acapacity many times that of the mould cavity or cavities.
  • the pump is left running during the4 cast.- ingr operation and solidiiication of the casting, whereby ⁇ to. balance leakage of air into the container when the mould is full ofthe poured metal. By this means also decar.-
  • the shell may be formed by various mihods, but is.
  • the invention also includes within the scope thereof apparatus for carrying out the method hereinbefore set forth', said apparatus comprising a permeable shell mould,
  • a vacuum accumulator and an evacuating pump for evacuating said accumulator, and a connection betweensaid' accumulator and said container, said connection including valve means for controlling the passage of air or gas from the container into the accumulator.
  • Fig. l is a cross-sectional elevation showing diagrammatically one arrangement of mould for carrying outthe method of casting according to the. invention.
  • Fig. 2 is a diagram illustrating the mould of Fig. 1 arranged in apparatus according to the invention.
  • a shell mould 1 of the desired object to vbe cast is made-such as by themethod according to the aforementioned U. S. applicationNo. 319,776/ 52, now U. S.
  • the mould is positioned in a metal container 2 and invested therein with a coarse dry refractory aggregate of angular nature indicated by the cross hatching 3.
  • the aggregate may for example have a particlev sizey of between onequarter and one-half of an inch.
  • the mould is provided with a pouring throat 4 whichL extends through the open top. of the container.
  • the top of the mould with the exceptionof the pouring throat 4, has built up thereon a collar 5 of solid investment ex' tending from the external surface of the throat to the sides of the container 2, thereby completing ⁇ the enclosurev of the mould 1 and the refractory aggregate 3.
  • the collar maybe formed from a thickviscous ceramic slurry poured or moulded roundthe throat. 4 of the mould onto the top of the ⁇ refractory investment, the slurry'beingsd,
  • Patented Mar. 17, 1959 welded into one side of the container and connected such as by a rubber tube or hose to the evacuating pump or accumulator.
  • the rubber hose is indicated at 7 and connects' -the pipe 6 with a pipe 8 in turn connected with a vacuum accumulator 9, a valve 10 being included in the pipe 8.
  • the accumulator 9 is connected directly with an evacuating pump 11.
  • the container 1 may be provided with a bottom wall having a number of orilices therein and the mould may be placed on a vacuum stillage incorporating a pump accumulator, and valve means, so that in operation the air or gas may be drawn through said oriiices.
  • the vacuum accumulator 9 with which the pipe 6 or the vacuum stillage is connected may have for example a volume of twenty to thirty times that of the mould cavity.
  • the mould When casting, the mould may be either hot or cold according to conditions and requirements. When the mould is employed hot, then with the second method of evacuation just above indicated, the metal tube protruding from the container is chilled-oft' before being connected with the rubber tube or hose.
  • the accumulator is iirst evacuated to the desired degree without drawing air from the mould, valve means between the accumulator and the container being closed at this time. At, or approximately at, the instant when pouring of the metal into the mould is commenced, said valve means are opened and the vacuumpreviously built up in the accumulator is then applied to. the container so as to obtain a high rate of extraction of air and gas from the mould cavity as the molten metal begins to flow down the throat. It will be understood that the use of the accumulator and opening of the valve means only at the time at which the casting is commenced enables a relatively small and economical evacuating pump to be employed. The use of a shell mould and highly permeable backing enables the air or gas to be extracted rapidly by the vacuum from the mould cavity or cavities.
  • the valve means is left open for the necessary-time required for the cast metal to solidify, which time may for example be of the order of tive minutes.
  • the pump is left running during this time so as to balance any leakage of air through the wall of the pouring throat and the collar by which the throat is sealed to the walls of the container at the upper end thereof.
  • the process according to the invention whilst having general application, is eminently applicable for the precision casting of long and thin objects of simple or complex shape, and enables a high surface iinish or definition to be obtained.
  • the invention also enables alloys which might otherwise be regarded as uncastable to be cast with considerably improved results.
  • casting alloys which in general provide inferior surface iinish by the normal casting processes as a result of high viscosity of the molten metal and consequent tendency to the trapping of small gas pockets on the surface of the casting, the invention overcomes these defects and in general enables Acastings f having good-definition to be obtained where not possible Y- permeable material, a one-piece elongated readily gas ⁇ by the usual methods.
  • An apparatus for use in the precision vacuum casting of relatively long thin objects comprising a substan tially air-tight container confining a body of readily gas permeable shell mold mounted in said container and conformably embedded in said body of material, said mold forming at least one relatively narrow cavity and having a pouring throat projecting above said container lthrough an opening provided therein and including a relatively narrow throat section communicating with said cavity whereby poured-casting material in molten state ills said throat to seal the cavity Vsubstantially air-tight in said container, an exhaust conduit extending through l the container into said body of material, an accumulator having a volumetric capacity at least many times that ofsaid mold and'said container, a vacuum pump connected to said accumulator, and a valve in the conduit between said container and the accumulator said valve lbeing normally closed in said apparatus to permit said accumulator to be evacuated and conditioned for sudden and continuing application of its vacuum to the interior of said container when said valve is opened.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
US531028A 1954-09-03 1955-08-29 Vacuum casting Expired - Lifetime US2877523A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB335807X 1954-09-03

Publications (1)

Publication Number Publication Date
US2877523A true US2877523A (en) 1959-03-17

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ID=10354768

Family Applications (1)

Application Number Title Priority Date Filing Date
US531028A Expired - Lifetime US2877523A (en) 1954-09-03 1955-08-29 Vacuum casting

Country Status (4)

Country Link
US (1) US2877523A (de)
CH (1) CH335807A (de)
FR (1) FR1135471A (de)
GB (1) GB808834A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3435885A (en) * 1966-05-19 1969-04-01 Garrett Corp Flask for making precision castings
US4007772A (en) * 1974-11-06 1977-02-15 Laedtke Donald O Apparatus for vacuum precision casting
US4660623A (en) * 1983-01-21 1987-04-28 Ashton Michael C Ceramic shell moulds, manufacture and use
US4951732A (en) * 1984-09-12 1990-08-28 Murata Kikai Kabushi Kaisha Traverse drum manufacturing method
CN102649153A (zh) * 2011-02-25 2012-08-29 加昌国际有限公司 模具真空阀装置

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ZA817886B (en) * 1980-11-21 1982-10-27 Steel Castings Res Method of casting using expendable patterns
EP0091533A1 (de) * 1982-04-08 1983-10-19 Oddino Dorigo Giesseinrichtung zur Herstellung von metallischen Gegenständen mit komplizierten Formen durch Schmelzen
GB2170742B (en) * 1985-01-31 1988-04-07 Maio Spa Mario Di Apparatus for use in producing castings by the }lost-wax} method

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1708011A (en) * 1929-04-09 Process aitd machine eob die casting
US2117114A (en) * 1934-12-07 1938-05-10 Richard C Tuma Apparatus for casting metal
DE716251C (de) * 1939-05-31 1942-01-15 Seelig & Hille R Faltbeutel mit Seitenverschlussfalzen sowie Verfahren und Vorrichtung zu seinem Herstellen
US2379401A (en) * 1942-04-16 1945-06-26 American Steel Foundries Method and apparatus for casting metal
US2434780A (en) * 1945-01-29 1948-01-20 United States Gypsum Co Process of molding hot materials
FR1039893A (fr) * 1950-08-04 1953-10-12 Ford Procédé et appareil pour les traitements thermiques, tels que la trempe des pièces moulées
US2660770A (en) * 1950-09-06 1953-12-01 Walworth Co Casting apparatus
US2718041A (en) * 1954-03-04 1955-09-20 Int Harvester Co Frangible expendable mold and pouring opening protective device

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1708011A (en) * 1929-04-09 Process aitd machine eob die casting
US2117114A (en) * 1934-12-07 1938-05-10 Richard C Tuma Apparatus for casting metal
DE716251C (de) * 1939-05-31 1942-01-15 Seelig & Hille R Faltbeutel mit Seitenverschlussfalzen sowie Verfahren und Vorrichtung zu seinem Herstellen
US2379401A (en) * 1942-04-16 1945-06-26 American Steel Foundries Method and apparatus for casting metal
US2434780A (en) * 1945-01-29 1948-01-20 United States Gypsum Co Process of molding hot materials
FR1039893A (fr) * 1950-08-04 1953-10-12 Ford Procédé et appareil pour les traitements thermiques, tels que la trempe des pièces moulées
US2660770A (en) * 1950-09-06 1953-12-01 Walworth Co Casting apparatus
US2718041A (en) * 1954-03-04 1955-09-20 Int Harvester Co Frangible expendable mold and pouring opening protective device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3435885A (en) * 1966-05-19 1969-04-01 Garrett Corp Flask for making precision castings
US4007772A (en) * 1974-11-06 1977-02-15 Laedtke Donald O Apparatus for vacuum precision casting
US4660623A (en) * 1983-01-21 1987-04-28 Ashton Michael C Ceramic shell moulds, manufacture and use
US4951732A (en) * 1984-09-12 1990-08-28 Murata Kikai Kabushi Kaisha Traverse drum manufacturing method
CN102649153A (zh) * 2011-02-25 2012-08-29 加昌国际有限公司 模具真空阀装置

Also Published As

Publication number Publication date
GB808834A (en) 1959-02-11
CH335807A (de) 1959-01-31
FR1135471A (fr) 1957-04-29

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