EP0474078B1 - Coubé de métall à contre-gravité sous utilisation d'un moule perdue particulièrement soutenu avec revêtement d'épaisseur mince - Google Patents

Coubé de métall à contre-gravité sous utilisation d'un moule perdue particulièrement soutenu avec revêtement d'épaisseur mince Download PDF

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Publication number
EP0474078B1
EP0474078B1 EP19910114237 EP91114237A EP0474078B1 EP 0474078 B1 EP0474078 B1 EP 0474078B1 EP 19910114237 EP19910114237 EP 19910114237 EP 91114237 A EP91114237 A EP 91114237A EP 0474078 B1 EP0474078 B1 EP 0474078B1
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EP
European Patent Office
Prior art keywords
shell
support media
molten metal
mold cavity
housing
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Expired - Lifetime
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EP19910114237
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German (de)
English (en)
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EP0474078A1 (fr
Inventor
George D. Chandley
Richard T. Carter
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Hitchiner Manufacturing Co Inc
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Hitchiner Manufacturing Co Inc
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    • 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
    • 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

Definitions

  • the present invention relates to a method of casting molten metal according to the preamble of claim 1 and to an apparatus for countergravity casting of molten metal, respectively, according to the preamble of claim 12.
  • the present invention relates to the countergravity casting of molten metal using a gas permeable investment shell mold provided with a thin mold wall that better tolerates pattern removal stresses and that is supported in a compacted particulate support media during the casting process.
  • a plurality of expendable (e.g., meltable) patterns of the article to be cast are first formed and then assembled with suitable ingate patterns and the like to form a pattern assembly or tree.
  • the pattern assembly is then invested with refractory particulate by alternately dipping the pattern assembly in a refractory slurry (comprising refractory powder and a suitable binder solution capable of hardening during drying under ambient conditions) and then dusted or stuccoed with coarser refractory powder.
  • the sequence of dipping and stuccoing is repeated to build up a multi-layered refractory shell having a sufficient thickness to resist stresses imparted thereto by subsequent pattern removal, firing and metal casting operations.
  • the pattern removal operation typically has been carried out by steam autoclaving wherein the invested pattern assembly is placed in a steam autoclave heated to a temperature in the range of about 135°C (275°F) to about 177°C (350°F) to melt out the pattern from the refractory shell.
  • prior art workers have experienced damage (e.g., cracking) to the refractory shell during the steam autoclaving step as a result of thermal expansion of the pattern (e.g., wax) relative to the refractory shell.
  • damage e.g., cracking
  • prior art workers have increased the thickness of the shell to better withstand these stresses.
  • Aforementioned US-A-4,791,977 describes stresses imposed on the refractory shell mold during the vacuum-assisted countergravity casting of molten metal therein.
  • that patent recognizes that harmful stresses can be imposed on the shell as a result of internal metallostatic pressure exerted thereon by the metal cast therein in conjunction with the external vacuum applied about the shell mold during the casting process.
  • the patent recognizes that such stresses when combined with the high temperatures of the metal in the shell mold can cause shell wall movement, metal penetration into the walls, metal leakage and outright failure of the shell mold, especially if there are any structural defects in the shell.
  • this patent provides a means of reducing such stresses on the investment shell mold (i.e., by using a differential pressure technique between the internal mold fill passage and vacuum chamber external of the shell), the investment shell mold used in that patent is still required to have a conventional shell wall thickness and strength to withstand stresses during pattern removal and molten metal casting.
  • the present invention contemplates an improved, economical countergravity casting method and apparatus involving forming an expendable pattern of an article to be cast and comprising a meltable material that expands upon heating, investing the pattern with particulate mold material in multiple layers so controlled as to form a refractory shell having a wall thickness not exceeding about 3 mm (.12 inch) about the pattern and heating the invested pattern, such as by steam autoclaving, to remove the pattern from the shell to leave a mold cavity therein.
  • a refractory particulate support media is disposed about the thin shell mold with the mold cavity communicated to a lower molten metal inlet disposed external of the support media.
  • the mold cavity is evacuated while, concurrently, a pressure is so applied to the support media as to compress the support media about the refractory shell to support the shell against casting stresses when the molten metal is countergravity cast into the evacuated mold cavity while the molten metal inlet is communicated to a source of molten metal.
  • a refractory shell mold having a wall thickness not exceeding about 3 mm (.12 inch) in the practice of the invention is based on the discovery, contrary to accepted prior art practice, that such thin shell walls are better able to tolerate stresses imposed thereon by pattern expansion during the pattern removal operation.
  • the invention relates to the discovery that the permeability of thin shell molds does not increase in direct proportion to reductions in shell wall thickness but rather in an unexpectedly greater manner.
  • such thin shell walls i.e., not exceeding about 3 mm (.12 inch) wall thickness
  • This increased shell permeability has been found to relieve the stresses imposed on the shell during pattern removal by steam autoclaving by enhancing infiltration into the shell of the molten skin initially melted on the pattern. Moreover, the increased shell mold permeability shortens the time for pattern removal by facilitating ingress of the steam to the pattern surface.
  • a refractory shell mold having such thin wall thickness i.e., not exceeding about 3 mm (.12 inch)
  • Use of a refractory shell mold having such thin wall thickness is also based on the discovery that such a thin shell mold can be adequately supported to withstand stresses imposed thereon during differential pressure, countergravity casting by rigidizing or compressing a particulate support media about the shell concurrent with the mold cavity being evacuated.
  • the thin shell mold is disposed in a loose particulate support media (e.g., loose foundry sand) contained in a vacuum housing and a pressure transmitting means is moved relative to the vacuum housing and the support media to compress the support media about the shell when the vacuum housing is evacuated to evacuate the mold cavity for casting.
  • the pressure transmitting means may comprise a movable wall of the vacuum housing that is subjected to ambient pressure on the outside and a relative vacuum on the inside to so compress the support media about the shell mold as to support the shell against casting stresses.
  • the pressure transmitting means may alternately comprise a pressurized bladder disposed in contact with the support media for compressing the support media about the thin shell for the same purpose.
  • Figure 1 is a side elevation of a pattern assembly.
  • Figure 2 is a sectioned, side elevation of the pattern assembly after investing with particulate mold material.
  • Figure 3 is a sectioned, side elevation of the thin shell mold after the pattern assembly is removed by steam autoclaving
  • Figure 4 is a sectioned side elevation of a countergravity casting apparatus in accordance with the invention wherein the shell mold is disposed in rigidized particulate support media in a vacuum housing and the external molten metal inlet to the shell mold is immersed in an underlying pool of molten metal.
  • Figure 5 is a sectioned side elevation of a countergravity casting apparatus in accordance with another embodiment of the invention.
  • Figure 6 is a sectioned side elevation of a countergravity casting apparatus in accordance with still another embodiment of the invention.
  • Fig. 1 an expendable pattern assembly or tree 10 comprising a central, cylindrical riser-forming portion 12 and a plurality of mold cavity-forming portions 14 each connected to the riser-forming portion 12 by a respective ingate-forming portion 16.
  • the mold cavity-forming portions 14 are configured in the shape of the article or part to be cast and are spaced apart about the periphery of the riser-forming portion 12 and along the length thereof as shown.
  • each mold cavity-forming portion 14 and its respective ingate-forming portion 16 are injection molded and then manually attached (e.g., wax welded or adhered) onto the riser-forming portion 12.
  • the riser-forming portion 12 is formed by injection molding as a separate piece.
  • a refractory frusto-conical collar 18 is attached (e.g., wax welded or adhered) to the lower end of the riser-forming portion 12.
  • the pattern assembly 10 is preferably made of a meltable, solid (non-porous) material which expands upon heating as will be explained.
  • Wax is the preferred material for the pattern assembly due to its low cost and predictable properties.
  • the pattern wax melts in the range of about 54.4°C (130°F) to about 65.6°C (150°F).
  • wax viscosity must be selected to avoid shell cracking during the pattern removal (e.g., wax viscosity at 76.7°C (170°F) should be less than 130 cPs (1300 centipoise)).
  • Urea may also be useful as a pattern material and melts in the range of about 112.8°C (235°F) to about 129.4°C (265°F).
  • the various portions 12,14,16 of the pattern assembly 10 be made of the same pattern material so long as the pattern assembly 10 is subsequently removable by heating, such as steam autoclaving, as will be described.
  • the pattern assembly 10 is invested with multiple layers of refractory material 22 to form a thin shell 30 thereabout.
  • the pattern assembly is invested by repeatedly dipping it in a refractory slurry (not shown) comprising a suspension of a refractory powder (e.g., zircon, alumina, fused silica and others) in a binder solution, such as ethyl silicate or colloidal silica sol, and small amounts of an organic film former, a wetting agent and a defoaming agent.
  • a refractory slurry comprising a suspension of a refractory powder (e.g., zircon, alumina, fused silica and others) in a binder solution, such as ethyl silicate or colloidal silica sol, and small amounts of an organic film former, a wetting agent and a defoaming agent.
  • a binder solution such as ethyl silicate or colloidal silica sol
  • the slurry coating is hardened using forced air drying or other means to form a refractory layer on the pattern assembly 10 or on the previously formed refractory layer.
  • This sequence of dipping, stuccoing and drying is repeated until a multi-layered shell 30 of desired wall thickness t about the mold cavity-forming portions 14 is built up.
  • the shell formation process i.e., dipping, stuccoing and drying
  • a multi-layer refractory shell 30 having a maximum wall thickness t not exceeding about 3 mm (.12 inch) about the mold cavity-forming portions 14.
  • this wall thickness has been discovered to exhibit a surprising ability to accommodate stresses imposed on the shell during pattern removal by steam autoclaving.
  • a shell wall thickness not exceeding about 3 mm (.12 inch) is built up or comprised of four to five refractory layers formed by the repetitive dipping, stuccoing and drying sequence described hereinabove.
  • Fig. 3 illustrates the refractory shell 30 after removal of the pattern assembly 10 by steam autoclaving.
  • the refractory shell 30 is shown positioned inside a steam autoclave 34 (schematically shown) of conventional type; e.g., model 286PT available from Leeds and Bradford Co.
  • a steam autoclave 34 (schematically shown) of conventional type; e.g., model 286PT available from Leeds and Bradford Co.
  • removal of the pattern assembly 10 leaves a thin refractory shell 30 having the mold cavities 36 interconnected to the central riser 37 via the respective lateral ingates 38.
  • the riser 37 is open at the lower and upper ends.
  • the invested pattern assembly 40 Fig. 2 is subjected to steam at a temperature of about 135°C (275°F) to about 177°C (350°F) (steam pressure of about 5.62 bar (80 psi) to about 7.73 bar (110 psi)) for a time sufficient to melt the pattern assembly 10 out of the refractory shell 30.
  • a molten surface film is melted on the pattern assembly 10 by ingress of the steam through the gas permeable refractory shell 30.
  • the permeability of the thin refractory shell 30 is surprisingly and unexpectedly able to absorb a major portion of this initial melted surface film and thereby relieve pattern expansion forces that would otherwise be exerted on the shell 30.
  • the remainder of the pattern assembly 10 is melted and, for the most part, drains from the refractory shell 30 through the opening 18a in the collar 18 therein.
  • the wall thickness of the refractory shell 30 is controlled in accordance with the invention so as not to exceed about 3 mm (.12 inch).
  • This shell wall thickness has been found to exhibit an unexpectedly high permeability (e.g., as measured by a known nitrogen permeability test conducted at 1038°C (1900°F) adopted by the Investment Casting Institute) for absorbing the initial melted surface film of pattern material during steam autoclaving.
  • a refractory shell 30 (fired) at about 982°C (1800°F) having a wall thickness of about 3 mm (.12 inch) (4 refractory layers) has been measured (by the aforementioned nitrogen permeability test) to exhibit a gas permeability of more than twice that exhibited by a like shell having twice the thickness (i.e., a shell wall thickness of 6 mm (.25 inch) and comprising eight refractory layers).
  • the gas permeability of the fired refractory shell 30 of 3 mm (.12 inch) wall thickness was measured as 316-468 cc of N2/minute compared to only 80-120 cc of N2/minute for the like shell of 6 mm (.25 inch) wall thickness.
  • the fired refractory shell 30 is so formed in accordance with the invention as to exhibit a gas permeability of at least generally three times that of a like shell of twice the wall thickness.
  • this unexpectedly high permeability of the thin refractory shell 30 enhances the ability of the refractory shell wall to absorb the initial melted surface film on the pattern assembly 10 formed during steam autoclaving to relieve any stresses that would normally be imposed on the shell as a result of thermal expansion of the pattern assembly 10 relative to the refractory shell 30.
  • a decreased (thinner) shell wall thickness provides a significantly improved response to steam autoclaving with reduced shell distortion and damage, such as cracking. Not only is shell distortion and damage reduced but also the time required for pattern removal by steam autoclaving is substantially reduced by virtue of better ingress of the steam through the high permeability shell 30 and resulting faster heating of the pattern assembly 10.
  • the quantity of refractory particulate required for the refractory shell 30 is significantly reduced since a thinner shell wall thickness is used.
  • the cost of casting is thereby significantly reduced; e.g., cost reductions of 40% to 75% are achievable based upon savings in the amount of refractory material used.
  • the use of a thin-walled shell mold permits closer spacing of the mold cavity-forming portions 14 and the ingates 16 to substantially increase the number of castings that can be made per mold. Overall production output is increased at reduced cost in like manner (except for wall thickness).
  • Table I sets forth comparative data relating to a so-called loading factor (i.e., the number of parts castable per mold) for a given part (e.g., an automobile rocker, window latch and a cleat) when using thick-walled shells (i.e., 6 mm (.25 inch) shell wall thickness) and when using the thin-walled shells 30 of the invention.
  • a so-called loading factor i.e., the number of parts castable per mold
  • a given part e.g., an automobile rocker, window latch and a cleat
  • thick-walled shells i.e., 6 mm (.25 inch) shell wall thickness
  • Both the thick-walled shell (9 slurry dips/stuccoes) and the thin-walled shell (4-5 slurry dips/stuccoes) were prepared in like manner using like slurries and stuccoes (e.g., initial slurry dip containing 200 mesh fused silica (15.2 weight %) and 325 mesh zircon (56.9 weight %), colloidal silica sol binder (17.8 weight %) and water (10.1 weight %) and subsequent slurry dips containing Mulgrain® M-47 mullite (15.1 weight %), 200 mesh fused silica (25.2 weight %) and 600 mesh zircon (35.3 weight %), ethyl silicate binder (15.6 weight %) and isopropanol (8.8 weight %) and stuccoed in sequence by about 100 mesh zircon, 60 mesh Mulgrain M-47 mullite and the balance being stuccoed by about 25 mesh Mulgrain M-47 mullite.
  • the shells were
  • the thinner shell molds of the invention significantly increase the loading factor (i.e., parts castable per mold) and significantly reduce the amount of refractory material needed to form the fired shell. All this is achieved while also achieving equivalent or better values for mold distortion and damage during the steam autoclaving operation.
  • molten metal is differential pressure, countergravity cast into the thin shell mold 30 (after the shell is fired at about 982°C (1800°F)) as illustrated in Fig. 4.
  • the thin shell mold 30 is supported in a loose refractory particulate support media 60 itself contained in a vacuum housing 70.
  • the vacuum housing 70 includes a bottom support wall 72, an upstanding side wall 73 and a movable top end wall 74 defining therewithin a vacuum chamber 76.
  • the bottom wall 72 and the upstanding side wall 73 are formed of gas impermeable material, such as metal, while the movable top end wall 74 comprises a gas permeable (porous) plate 75 having a vacuum plenum 77 connected thereto to define a vacuum chamber 78 above (outside) the gas permeable plate 75.
  • the vacuum chamber 78 is connected to a source of vacuum, such as a vacuum pump 80, by conduit 82.
  • the movable top end wall 74 includes a peripheral seal 84 that sealingly engages the interior of the upstanding side wall 73 to allow movement of the top end wall 74 relative to the side wall 73 while maintaining a vacuum seal therebetween.
  • a ceramic fill tube 90 disposed in housing 70 and providing a lower molten metal inlet to the mold cavities 36 via the riser 37 and the respective ingates 38 is sealingly engaged to the frusto-conical collar 18 as the mold is placed thereon.
  • a refractory cap 20 is placed atop the shell mold to close off the upper end of the riser 37.
  • the loose refractory particulate support media 60 e.g., loose foundry silica sand of about 60 mesh
  • the housing 70 is vibrated to aid in settling of the support media 60 in the chamber 76 about the shell 30.
  • the movable top end wall 74 is then positioned in the open upper end of the housing 70 with the peripheral seal 84 sealingly engaging the upstanding side wall 73 and with the inner side of the gas permeable plate 75 facing and in contact with the support media 60, Fig. 4.
  • the casting apparatus 100 is positioned above a source 102 (e.g., a pool) of the molten metal 104 to be cast.
  • a source 102 e.g., a pool
  • the molten metal 104 is contained in a casting vessel 106.
  • a vacuum is then drawn in the vacuum chamber 78 of the vacuum bell 77 and hence in the vacuum chamber 76 through the gas permeable plate 75 by actuation of the vacuum pump 80.
  • Evacuation of the chamber 76 evacuates the mold cavities 36 through the thin gas permeable shell wall.
  • the level of vacuum in chamber 76 is selected sufficient to draw the molten metal 104 upwardly from the pool 102 into the mold cavities 36 when the fill tube 90 is immersed in the molten metal 104 as shown in Fig. 4.
  • the top end wall 74 When the vacuum is drawn in vacuum chambers 76,78, the top end wall 74 is subjected to atmospheric (or ambient) pressure on the side thereof external of the peripheral seal 84 while the inner side of the plate 75 is subjected to a relative vacuum.
  • This pressure differential across the top end wall 74 causes the top wall 74 to move downwardly relatively to side wall 73 and causes the plate 75 to exert sufficient pressure on the support media 60 so as to compress or rigidize the support media 60 about the shell 30 to support it against casting stresses.
  • a pressure is applied concurrently by the plate 75 to compress the support media 60 about the shell 30 to support it against casting stresses.
  • the amount of pressure applied by the plate 75 to compress the support media 60 can be controlled by controlling the level of vacuum established in the vacuum chamber 76.
  • the molten metal 104 will be drawn upwardly through the fill tube 90 through the riser 37 and into the mold cavities 36 via the lateral ingates 38. The molten metal 104 is thereby vacuum countergravity cast into the mold cavities 36.
  • This reduction in stress in conjunction with support of the shell 30 by the support media 60 permits countergravity casting of the high temperature molten metal 104 into the thin shell 30 (having a wall thickness not exceeding about .12 inch) without harmful mold wall movement and molten metal penetration into the mold wall.
  • the surrounding support media 60 also aids in preventing the molten metal 104 from leaking through the defect and, in any event, confines any leakage in proximity to the shell 30 to prevent damage to the casting apparatus, permitting vacuum to be held until the castings solidify.
  • the casting assembly 100 is moved upwardly to remove the fill tube 90 from the molten metal pool.
  • the top wall 74 of the housing 70 is then removed at an unload station (not shown) to allow removal of the support media 60 and the metal-filled shell 30 from the vacuum chamber 76.
  • the support media 60 can be recycled for reuse in casting another shell 30.
  • the metal-filled shell 30 is allowed to cool to ambient.
  • the shell 30 is easily removed from the solidified casting by virtue of its thin wall thickness. For example, cooling of the metal-filled shell 30 often causes the shell 30 to simply pop off the casting due to thermal stresses imposed on the shell during cooling. In general, considerably less time is required to remove the thin shell 30 than to remove shell molds having thicker wall thicknesses heretofore used.
  • a casting apparatus 100' of another embodiment of the invention is illustrated.
  • like features of Fig. 4 are represented by like reference numerals primed.
  • the casting apparatus 100' of Fig. 5 differs from the casting apparatus 100 of Fig. 4 in using an annular vacuum bell 110' about the housing 70' and a flexible, gas impermeable membrane 112' sealingly disposed on the open upper end of the housing 70' (providing a movable housing top end wall) for applying a pressure to the support media 60' when the housing 70' is evacuated.
  • the vacuum plenum 110' defines an annular vacuum chamber 114' about the vacuum chamber 76' of the housing 70' and is interconnected thereto by an annular gas permeable (porous) side wall housing section 116'.
  • the flexible, gas impermeable membrane 112' When the vacuum is drawn in the vacuum chamber 76', the flexible, gas impermeable membrane 112' is subjected to atmospheric pressure on the outside surface 112a' and to the relative vacuum on the inside surface 112b', causing the membrane 112' to compress the loose refractory particulate support media 60' about the thin shell mold 30' to support it against casting stresses in the manner described hereinabove with respect to Fig. 4 as the molten metal is urged upwardly from the underlying pool through the fill tube 90' and the riser 37' and into the mold cavities 36' via the ingates 38'.
  • the embodiment of Fig. 5 functions and offers advantages described above for the embodiment of Fig. 4.
  • FIG. 6 a casting apparatus 100'' of still another embodiment of the invention is illustrated wherein like features of Fig. 4 are represented by like reference numerals double primed.
  • the embodiment of Fig. 6 differs from that of Fig. 4 in using one or more annular fluid pressurizable bladders 120'' (one shown) disposed in contact with the refractory particulate support media 60" in the housing 70'' to exert a pressure on the support media 60'' to compress it about the thin shell mold 30'' when the mold cavities 36'' are evacuated during countergravity casting.
  • the housing 70'' includes a non-movable top end wall 74'' which comprises a gas permeable plate 75'' sealed to the top of the housing 70'' by seal 84'' and a vacuum bell 77'' connected to the plate 75''.
  • the vacuum chamber 78'' of the bell 77'' overlies the gas permeable portion 75a'' of the plate 75'' so as to evacuate the vacuum chamber 76'' of the housing 70'' by a means of vacuum pump 80'' communicating thereto via conduit 82''.
  • the bladder 120'' is pressurized by a suitable gas supply 121'', such as compressed air, through suitable gas supply pipes 122''. Pressurization of the bladder 120'' exerts a pressure on the refractory particulate support media 60'' to compress it about the shell 30'' to support it against casting stresses in the same manner as described hereinabove for the preceding embodiments.
  • a suitable gas supply 121'' such as compressed air
  • Pressurization of the bladder 120'' exerts a pressure on the refractory particulate support media 60'' to compress it about the shell 30'' to support it against casting stresses in the same manner as described hereinabove for the preceding embodiments.
  • the embodiment of Fig. 6 is similar in function to the preceding embodiments of Figs. 4 and 5.

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Claims (19)

  1. Procédé de moulage d'un métal fondu, comprenant les étapes suivantes exécutées successivement :
    (a) la formation d'un modèle consommable (10) d'un article à mouler, le modèle comprenant un matériau fusible qui se dilate par chauffage,
    (b) l'enrobage du modèle (10) d'une matière réfractaire particulaire (22) de moule en plusieurs couches pour la formation d'une carapace réfractaire (30) autour du modèle,
    (c) le chauffage du modèle enrobé (40) afin que le modèle (10) soit retiré de la carapace (30) et laisse une cavité de moulage (36) dans la carapace,
    (d) la disposition d'une matière particulaire réfractaire (60) de support autour de la carapace mince (30), la cavité de moulage (36) communiquant avec une entrée de métal fondu (18, 18a) placée à l'extérieur de la matière de support,
    (e) l'évacuation de la cavité de moulage (36), et
    (f) le moulage du métal fondu dans la cavité évacuée de moulage (36) alors que l'entrée de métal fondu communique avec une source de métal fondu et la carapace (30) est supportée dans la matière de support (60),
       le procédé de moulage étant caractérisé en ce que
       il comprend une opération de moulage contre la pesanteur d'un métal fondu aspiré vers le haut dans la cavité évacuée de moulage (36) lorsque l'entrée de métal fondu (18, 18a) communique avec une source de métal fondu placée au-dessous,
       au cours de l'étape (b) de formation de la carapace, l'application des couches de la matière du moule est réglée de manière qu'elle forme une mince carapace réfractaire (30) ayant une épaisseur de paroi qui ne dépasse pas 3 mm environ (0,12 pouce), et
       le procédé comporte en outre l'application d'une pression à la matière de support (60) en même temps que la cavité de moulage (36) est évacuée afin que la matière de support placée autour de la mince carapace (30) soit comprimée et supporte la carapace lorsqu'elle encaisse les contraintes de moulage.
  2. Procédé selon la revendication 1, dans lequel la mince carapace en couches (30) est formée de manière qu'elle possède une perméabilité aux gaz supérieure au double de celle d'une carapace analogue ayant deux fois son épaisseur de paroi.
  3. Procédé selon la revendication 2, dans lequel la carapace (30) est formée de manière qu'elle présente une perméabilité aux gaz au moins trois fois supérieure à celle que présente la carapace analogue.
  4. Procédé selon la revendication 1, dans lequel, au cours de l'étape (c), le modèle enrobé (10) est traité à l'autoclave par de la vapeur d'eau afin que le modèle soit retiré de la carapace mince (30) et laisse une cavité de moulage (36).
  5. Procédé selon la revendication 1, dans lequel, au cours de l'étape (d), la carapace (30) est supportée dans la matière de support (60) à l'intérieur d'un boîtier sous vide (70), et un dispositif (74) de transmission de pression est déplacé par rapport au boîtier sous vide (70) et à la matière de support (60) lorsque le boîtier est évacué afin qu'il exerce la pression sur la matière de support.
  6. Procédé selon la revendication 5, dans lequel le dispositif de transmission de pression comporte une paroi mobile (74) du boîtier (70) destinée à exercer une pression sur la matière de support (60).
  7. Procédé selon la revendication 6, dans lequel la paroi (74) est soumise à un vide relatif à sa face interne et à la pression ambiante à sa face externe.
  8. Procédé selon la revendication 5, dans lequel le dispositif de transmission de pression comporte une vessie (120'') placée au contact de la matière de support dans le boîtier (70'') et mise sous pression afin qu'elle comprime la matière de support lorsque la cavité de moulage (36'') est évacuée.
  9. Procédé selon la revendication 1, dans lequel le modèle consommable (10) est formé de cire.
  10. Procédé selon la revendication 1, dans lequel le modèle consommable (10) est formé d'urée.
  11. Procédé selon la revendication 1, dans lequel l'étape (d) de disposition de la matière de support (60) autour de la carapace comprend la disposition d'une matière particulaire réfractaire de support autour de la carapace mince, contenue dans une chambre sous vide, la cavité de moulage communiquant avec une entrée inférieure (18, 18a) de métal fondu placée à l'extérieur de la chambre sous vide.
  12. Appareil de moulage d'un métal fondu contre la pesanteur, comprenant :
    (a) une matière particulaire réfractaire de support (60) disposée dans un boîtier (70),
    (b) une carapace réfractaire (30) ayant une cavité de moulage (36) délimitée par une paroi de moule placée dans la matière de support (60),
    (c) un dispositif (78, 80, 82) d'évacuation de la cavité de moulage (36), et
    (d) une entrée (90) de métal fondu placée à l'extérieur de la matière de support (60) afin que la cavité de moulage (36) et une source (102) de métal fondu communiquent, lorsque la cavité de moulage (36) est évacuée, si bien que le métal fondu est chassé dans la cavité évacuée de moulage (36),
       l'appareil étant caractérisé en ce que la carapace a une épaisseur de paroi de moule qui ne dépasse pas 3 mm (0,12 pouce), et
       l'entrée de métal fondu est une entrée inférieure (90) destinée à faire communiquer la cavité de moulage (36) avec une source (102) de métal fondu qui est placée au-dessous, et un dispositif (74) est destiné à appliquer une pression à la matière de support (60) pendant l'évacuation de la cavité de moulage (36), la pression étant telle que la matière de support (60) est comprimée autour de la carapace (30) afin que celle-ci soit supportée lorsqu'elle subit les contraintes de moulage.
  13. Appareil selon la revendication 12, dans lequel l'entrée de métal fondu comprend un tube (90) de remplissage dépassant de la carapace (30) à l'extérieur de la matière de support (60).
  14. Appareil selon la revendication 12, dans lequel le dispositif d'application d'une pression à la matière de support (60) comporte une paroi mobile (74) du boîtier (70), la paroi mobile (74) étant soumise à une pression différentielle lorsqu'une chambre (76) du boîtier (70) est évacuée afin que la paroi (74) se déplace par rapport au boîtier (70) et à la matière de support (60) et comprime la matière de support autour de la carapace (30).
  15. Appareil selon la revendication 14, dans lequel la paroi mobile comporte une paroi (74) d'extrémité perméable aux gaz du boîtier, la paroi d'extrémité ayant une face interne destinée à être au contact de la matière de support (60) et une cloche sous vide (77) recouvrant sa face externe, la cloche sous vide (77) pouvant être évacuée à l'extérieur afin que la chambre (76) soit évacuée par l'intermédiaire de la paroi d'extrémité perméable aux gaz (74) et étant soumise à la pression ambiante à l'extérieur de manière que la paroi (74) se déplace par rapport au boîtier (70) et exerce une pression sur la matière de support (60) lorsque la chambre (76) est évacuée.
  16. Appareil selon la revendication 14, dans lequel la paroi mobile comporte une paroi souple d'extrémité (112') du boîtier (70') qui est imperméable aux gaz.
  17. Appareil selon la revendication 12, dans lequel le dispositif d'application d'une pression à la matière de support comporte une vessie (120'') qui peut être mise sous pression et qui est placée au contact de la matière de support (60'') dans la chambre (76'').
  18. Appareil selon la revendication 12, dans lequel la matière particulaire réfractaire de support comporte un sable fluide de fonderie.
  19. Appareil selon la revendication 12, dans lequel le boîtier (70) a une chambre sous vide (76),
       la matière particulaire réfractaire fluide de support (60) est placée dans la chambre (76) afin qu'elle soit comprimée autour de la carapace (30), et
       l'entrée inférieure (90) de métal fondu est placée à l'extérieur de la chambre sous vide (76).
EP19910114237 1990-09-06 1991-08-24 Coubé de métall à contre-gravité sous utilisation d'un moule perdue particulièrement soutenu avec revêtement d'épaisseur mince Expired - Lifetime EP0474078B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57931990A 1990-09-06 1990-09-06
US579319 1990-09-06

Publications (2)

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EP0474078A1 EP0474078A1 (fr) 1992-03-11
EP0474078B1 true EP0474078B1 (fr) 1995-11-29

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EP19910114237 Expired - Lifetime EP0474078B1 (fr) 1990-09-06 1991-08-24 Coubé de métall à contre-gravité sous utilisation d'un moule perdue particulièrement soutenu avec revêtement d'épaisseur mince

Country Status (10)

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EP (1) EP0474078B1 (fr)
JP (1) JPH07110404B2 (fr)
CN (1) CN1047547C (fr)
AU (1) AU635858B2 (fr)
BR (1) BR9103830A (fr)
CA (1) CA2049228C (fr)
DE (1) DE69114954T2 (fr)
MX (1) MX173895B (fr)
RU (1) RU2039629C1 (fr)
YU (1) YU47814B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9833833B2 (en) 2013-03-14 2017-12-05 Hitchiner Manufacturing Co., Inc. Refractory mold and method of making

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5303762A (en) * 1992-07-17 1994-04-19 Hitchiner Manufacturing Co., Inc. Countergravity casting apparatus and method
WO1994020240A1 (fr) * 1993-03-12 1994-09-15 Hitachi Metals, Ltd. Appareil de coulage par aspiration sous vide et son procede d'utilisation
JPH0818122B2 (ja) * 1993-02-02 1996-02-28 第一鋳造株式会社 減圧シェルモールド鋳造法
GB9724568D0 (en) * 1997-11-19 1998-01-21 Castings Dev Centre The Investment casting
JP2008531289A (ja) 2005-02-22 2008-08-14 ミルウォーキー・スクール・オブ・エンジニアリング 鋳造プロセス
CN101386066B (zh) * 2008-10-27 2010-06-09 秦中林 钢铁铸件在挤压机上进行铸造的方法
CN101850401A (zh) * 2010-05-31 2010-10-06 上虞新达精密铸造有限公司 一种熔模及利用该熔模的精密铸造工艺
CN102806314A (zh) * 2012-09-03 2012-12-05 贵州安吉航空精密铸造有限责任公司 一种铝合金薄壁细孔铸件的铸造方法
US9486852B2 (en) 2013-03-14 2016-11-08 Hitchiner Manufacturing Co., Inc. Radial pattern assembly
US9481029B2 (en) 2013-03-14 2016-11-01 Hitchiner Manufacturing Co., Inc. Method of making a radial pattern assembly
US8931544B2 (en) * 2013-03-15 2015-01-13 Metal Casting Technology, Inc. Refractory mold
KR101367200B1 (ko) * 2013-05-08 2014-02-26 지정욱 이중 주조 방법 및 장치
CN104399891A (zh) * 2014-11-27 2015-03-11 温州兰理工科技园有限公司 一种熔模精密制壳工艺与负压造型技术相结合的铸造方法
CN104972066A (zh) * 2015-06-15 2015-10-14 江苏万恒铸业有限公司 一种薄壳培砂浇注简易工艺
CN106513635B (zh) * 2016-12-16 2019-02-05 上海华培动力科技股份有限公司 用于耐高温合金真空吸铸工艺的双层空心筒熔模模壳结构
CN109719277A (zh) * 2017-10-30 2019-05-07 科华控股股份有限公司 耐热钢涡壳真空吸铸工艺的反重力补缩壳型结构
CN109465399B (zh) * 2018-12-26 2023-11-21 广东富华铸锻有限公司 一种含有减速器壳砂芯结构的浇注系统
JP6915206B2 (ja) * 2019-08-26 2021-08-04 呉政寛 薄肉シェルモールドの溶湯鍛造方法
CN114309474A (zh) * 2022-03-14 2022-04-12 成都航宇超合金技术有限公司 一种中小型单晶涡轮叶片的熔模铸造工艺

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1119223A (en) * 1964-07-09 1968-07-10 Dynamit Nobel Ag Process for the production of precision casting moulds
US3900064A (en) * 1972-12-04 1975-08-19 Hitchiner Manufacturing Co Metal casting
IT1121553B (it) * 1979-06-01 1986-04-02 Cattaneo Leopoldo Fasce elastiche e/o raschiaolio per motori termici e/o per tenute di qualsiasi tipo,con rigidita'periferica e deformazione in funzionamento a caldo controllata mediante intagli,fori,alleggerimenti e fessure praticati sulle superfici piane di appoggio della fascia elastica nella sede e metodi per la loro produzione
US4340108A (en) * 1979-09-12 1982-07-20 Hitchiner Manufacturing Co., Inc. Method of casting metal in sand mold using reduced pressure
US4589466A (en) * 1984-02-27 1986-05-20 Hitchiner Manufacturing Co., Inc. Metal casting
IN170880B (fr) * 1987-05-07 1992-06-06 Metal Casting Tech
US4791977A (en) * 1987-05-07 1988-12-20 Metal Casting Technology, Inc. Countergravity metal casting apparatus and process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9833833B2 (en) 2013-03-14 2017-12-05 Hitchiner Manufacturing Co., Inc. Refractory mold and method of making

Also Published As

Publication number Publication date
CN1059485A (zh) 1992-03-18
RU2039629C1 (ru) 1995-07-20
BR9103830A (pt) 1992-05-19
MX173895B (es) 1994-04-07
JPH04270024A (ja) 1992-09-25
YU47814B (sr) 1996-01-09
CN1047547C (zh) 1999-12-22
EP0474078A1 (fr) 1992-03-11
CA2049228A1 (fr) 1992-03-07
AU635858B2 (en) 1993-04-01
AU8249591A (en) 1992-03-12
DE69114954T2 (de) 1996-07-18
DE69114954D1 (de) 1996-01-11
CA2049228C (fr) 1996-10-15
JPH07110404B2 (ja) 1995-11-29
YU149191A (sh) 1994-06-24

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