Classifications

• • 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
  • B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/006—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using reactive gases

Definitions

• the present invention relates to a device for casting molten metal into a mold.
• low-pressure casting devices comprising a first enclosure in which is arranged a crucible containing the molten metal, and a second enclosure comprising a mold and an injection tube arranged to communicate with the molten metal .
• these devices do not allow a change of mold without causing a notable disturbance of the atmosphere above the molten metal.
• a device for casting a molten metal comprising a first sealed enclosure in which the molten metal is placed, connected by an injection tube to a mold placed in a second sealed enclosure, a separation member. being disposed on the injection tube outside the first enclosure, at a level higher than the molten metal when the injection tube is engaged in the molten metal.
• the separation member can be operated or restored without disturbing the atmosphere above the crucible.
• the separation member is disposed at one end of the injection tube adjacent to the second enclosure.
• the separating member can be operated or restored when the second enclosure is opened to take the filled mold and replace it with an empty mold.
• the separation member comprises a fusible metal membrane.
• the metal membrane has a composition identical or similar to the molten metal.
• the molten metal is retained by it, then it is released after melting of the membrane to spread in the mold.
• the device comprises a filter adjacent to the membrane, downstream of the latter by reference to the displacement of the molten metal in the injection tube in order to minimize the deformation of the membrane during a depression of the mold, and an annular wall disposed in the injection tube and delimiting therewith a blind annular space having a bottom offset from the fusible membrane downstream thereof so that during the rise of the metal molten in the injection tube most of the gas empri ⁇ son Avenue in the injection tube spreads in the annular space and therefore does not prevent the coming into contact of the molten metal with the fusible metal membrane.
• FIG. 1 is a schematic sectional view of a casting device according to the invention, -
• FIG. 1 is a sectional view of an embodiment of a separation member for the device of Figure 1.
• the device according to the invention comprises a crucible 1 surmounted by a removable cover 2 forming with the crucible 1 a first sealed enclosure containing a molten metal 3 having a free surface 4.
• the cover 2 comprises hatches visit 5 allowing, in a manner known per se, to add alloying elements or to put in place the devices necessary for conducting the fusion.
• the crucible 1 is sealed by refractory seals allowing the pressurization from a few decibars to a few bars, or vacuuming.
• the crucible 1 fitted with the cover 2 is placed inside a sealed or non-sealed oven 6 depending on the pressure level inside the crucible.
• a supply tube 7 connects the interior of the crucible to a source of gas under pressure, not shown.
• a mold 8 is placed above the crucible in a second sealed enclosure 9 and comprises, in a manner known per se, sensory organs not shown such as metal presence sensors, pressure sensors, and temperature sensors making it possible to control precisely the course of the casting.
• the mold 8 and the crucible 1 are connected by an injection tube 10 on which is disposed a separation member 11 such as a knife gate valve or a separation member as illustrated in FIG. 2.
• a separation member 11 such as a knife gate valve or a separation member as illustrated in FIG. 2.
• the separation member comprises a fusible metal membrane 12, for example a membrane having a composition identical to or close to that of the molten metal alloy.
• the fusible membrane 12 is disposed at the end of the injection tube 10 adjacent to the second enclosure 9 and is supported on a shoulder 13 extending radially inward of an annular wall 14 which s extends axially inside the injection tube 10.
• a metal or ceramic filter 15 is disposed downstream of the membrane 12 by reference to the displacement of the molten metal in the injection tube 10.
• the membrane 12 is mounted in a sealed manner in the injection tube 10, preferably in a manner allowing rapid replacement of the membrane 12, for example by mounting it removably in the annular wall 14, the membrane 12 being pressed against the internal shoulder 13 by the filter 15 itself kept pressed against the membrane 12 by a spacer 16 which bears on the underside 17 of the enclosure 9.
• the annular wall 14 disposed in the injection tube 10_ defines therewith a blind annular space 18 having a bottom 19 offset from the fusible membrane 12 downstream thereof. It will be noted that the presence of a separation member 11 on the injection tube 10 makes it possible not only to subject the mold and the molten metal to different pressures but also to maintain atmospheres of different compositions above the molten metal and in the mold.
• the enclosure 9 comprises a supply tube 21 and a suction tube 22.
• the interior of the crucible 1 is pressurized and the metal gradually rises in the injection tube 10.
• the surface of the metal reaches the lower edge of the annular wall 14
• most of the gas which was trapped between the fusible membrane 12 and the upper surface of the molten metal spreads in the annular gap 18 so that the gas included in the space 23 internal to the annular wall 14 can be easily compressed or even expelled by the rise of the molten metal.
• This arrangement promotes the rise of the molten metal in the central part of the injection tube 10 and allows bringing the molten metal into contact with the fusible membrane 12 to ensure that the latter melts and opens the separation member.
• the pressure in the enclosure 9 containing the mold can be varied.
• the invention also makes it possible to obtain composite material by infiltration of the liquid metal within a network of fibers or pores, this infiltration being facilitated by the depressurization of the enclosure containing the composite element.
• the membrane 12 When a casting has been carried out, the membrane 12 is very easily replaced, the membrane support 14 being subjected to tolerable heating.
• the fusible membrane can be replaced by a valve which can, if necessary, be controlled remotely before the opening of the enclosure containing the mold, so that the atmosphere above the molten metal is in no way disturbed.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Separation Using Semi-Permeable Membranes (AREA)

Applications Claiming Priority (3)

Publications (1)

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Country Status (2)

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Family Cites Families (6)

• 1995
  • 1995-01-25 WO PCT/FR1995/000089 patent/WO1995020449A1/fr not_active Ceased
  • 1995-01-25 EP EP95907706A patent/EP0804307A1/de not_active Ceased

Non-Patent Citations (1)

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