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Method of and apparatus for vacuum casting

  • US 5,431,212 A
  • Filed: 07/06/1994
  • Issued: 07/11/1995
  • Est. Priority Date: 07/20/1993
  • Status: Expired due to Fees
First Claim
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1. A method of vacuum casting comprising:

  • a first step of closing, with a gate member, a sprue of a cavity formed in a die;

    a second step of feeding molten metal stored in a molten metal storage tank through a molten metal passage to a molten metal reservoir which is communicated with the sprue through the gate member and is also communicated with the molten metal storage tank via the molten metal passage, until the lowest head of the molten metal fed into the molten metal reservoir becomes higher than the level of the sprue;

    a third step of reducing the pressure in the cavity, the third step being executed either before, simultaneously with or after the second step;

    a fourth step of communicating the sprue with the molten metal reservoir and also with the molten metal passage by moving the gate member when the pressure in the cavity has been reduced to a predetermined pressure; and

    a fifth step of having the interior of the molten metal reservoir isolated from the atmosphere and held gas tight while the molten metal having been fed into the molten metal reservoir is introduced into the cavity as a result of the communication brought about in the fourth step between the sprue and the molten metal reservoir, with the lowest head of molten metal in the reservoir being held to be higher than the level of the sprue during this time.

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