Claims
- 1. In casting apparatus, including
- a gas permeable mold having a vertical passage with a lower open end for introducing molten metal into mold cavity means therein
- a crucible for holding molten metal with its surface positioned beneath said mold
- power means for relatively moving said crucible and said mold toward and away from one another, and
- pressure means for applying a differential pressure to said mold and crucible to cause said molten metal to fill said mold cavity means through said vertical passage,
- that improvement consisting of
- a rigid, permanently crimpable metal fill pipe removably and sealingly connected to the lower open end of said vertical mold passage with its lower end extending vertically downwardly therefrom toward said crucible, and
- releasable fill pipe crimping means positioned between said mold and said crucible for selectively permanently crimping said fill pipe to close it after filling of said mold cavity means to prevent reverse flow of molten metal from said mold to said crucible as said mold and fill pipe are moved relatively away from said crucible.
- 2. Apparatus as claimed in claim 1, wherein
- said fill pipe is permanently closed by said crimping means by welding together the interior walls of said fill pipe.
- 3. In casting apparatus, including
- a gas-permeable mold having a vertical passage with a lower open end for introducing molten metal into mold cavity mean therein
- mold support means having a lower opening positioned beneath said mold passage lower open end
- a crucible for holding molten metal with its surface positioned beneath said mold support means
- power means for relatively moving said crucible and said mold toward and away from one another, and
- pressure means for applying a differential pressure to said mold and crucible to cause said molten metal to fill said mold cavity means through said vertical passage.
- that improvement consisting of
- a rigid, permanently crimpable metal fill pipe having a radially outwardly extending upper flange removably and sealingly interposed between and surrounding said mold passage lower open end and said mold support means lower opening connected with its lower end extending vertically downwardly therefrom toward said crucible, and
- releasable fill pipe crimping means positioned between said mold and said crucible for selectively permanently crimping said fill pipe to close it after filling of said mold cavity means to prevent reverse flow of molten metal from said mold to said crucible as said mold and fill pipe are moved relatively away from said crucible, said crimping means thereafter being opened to release said fill pipe for its removal.
- 4. A method of casting in a gas permeable mold, comprising the steps of:
- providing a gas-permeable mold having a vertical passage with a lower open end for introducing molten metal into mold cavity means therein
- providing a crucible for holding molten metal with its surface positioned beneath said mold
- providing a rigid, permanently crimpable metal fill pipe sealingly connected to the lower open end of said vertical mold passage with its lower end extending vertically downwardly therefrom toward said crucible
- relatively moving said mold and fill pipe toward said crucible to move the lower end of said fill pipe beneath the surface of molten metal in said crucible to introduce molten metal from said crucible into the lower end of said fill pipe
- applying a differential pressure to said mold and crucible to cause said molten metal to fill said mold cavity means through said fill pipe, and
- permanently crimping said fill pipe to close it after filling of said mold cavity means to prevent reverse flow of molten metal from said mold cavity means to said crucible as said mold and fill pipe are moved relatively away from said crucible.
- 5. Apparatus as claimed in claims 3 or 9, wherein
- said crucible contains molten metal at a predetermined temperature and
- said fill pipe melts at a temperature less than said predetermined temperature of said molten metal in said crucible.
- 6. A method of casting in a gas permeable mold, comprising the steps of:
- providing a gas permeable mold having a vertical passage with a lower open end for introducing molten metal into mold cavity means therein
- providing a mold support having a lower opening positioned beneath said mold passage lower open end
- providing a crucible for holding molten metal with its surface positioned beneath said mold support
- providing a rigid, permanently crimpable metal fill pipe having a radially outwardly extending upper flange removeably sealingly interposed between and surrounding said mold passage lower open end and said mold support lower opening with its lower end extending vertically downwardly therefrom toward said crucible
- relatively moving said mold and fill pipe toward said crucible to move the lower end of said fill pipe beneath the surface of molten metal in said crucible to introduce molten metal from said crucible into the lower end of said fill pipe
- applying a differential pressure to said mold and crucible to cause said molten metal to fill said mold cavity means through said fill pipe,
- crimping said fill pipe to close it after filling of said mold cavity means to prevent reverse flow of molten metal from said mold cavity means to said crucible as said mold and fill pipe are moved relatively away from said crucible, and finally
- removing said fill pipe from said mold and support.
- 7. A method as claimed in claims 6, 7, 8 or 10, wherein
- said fill pipe melts at a temperature less than the temperature of molten metal in said crucible.
- 8. A method as claimed in claim 4 wherein
- the interior walls of said fill pipe are permanently welded together by said crimping to permanently close said fill pipe.
- 9. Apparatus as claimed in claim 3 wherein said fill pipe is permanently closed by said crimping means by welding together the interior walls of said fill pipe.
- 10. A method as claimed in claim 6, wherein the interior walls of said fill pipe are permanently welded together by said crimping to permanently close said fill pipe.
- 11. Apparatus as claimed in claims 1, 2, or 9, wherein
- said fill pipe has a wall thickness of between 0.060 to 0.180 inches and is crimped at a distance of at least 1.5 times the pipe diameter from its upper end.
- 12. A method as claimed in claims 6, 7, 8 or 10 wherein said fill pipe has a wall thickness of between 0.060 to 0.180 inches and is crimped at a distance of at least 1.5 times the pipe diameter from its upper end.
BACKGROUND OF THE INVENTION
This application is a continuation-in-part of our application, Ser. No. 583,828, filed Feb. 27, 1984now abandoned. Its invention relates to metal casting apparatus and methods and, more particularly, to counter gravity, differential pressure, metal casting apparatus of the type generally disclosed in U.S. Pat. Nos. 3,863,706, 3,900,064 and 4,112,997, which are incorporated by reference herein.
Although the apparatus and methods disclosed in these patents have been in successful commercial use for many years, castings of certain high melting point metal alloys having wall thickness in excess of about 3/4 inch cannot be made economically by their use, since screens as disclosed in U.S. Pat. No. 4,112,997 cannot be used because they react with such alloys and without screens such thick castings require an uneconomical time to solidify.
In an attempt to find a solution, ceramic ball check valves have been used, but have proved to be both uneconomical and unreliable with many of such alloys, since they tend to erode the ceramic, causing the ball to jam in its open position, so that the molten metal can run back into the crucible before solidifying, resulting in ruined castings.
Accordingly, it is a major object of the invention to provide novel apparatus and methods for differential pressure, counter gravity, metal casting, particularly of certain high melting point metal alloys, to provide for the economical casting of relatively thick walled castings of such alloys.
This has been accomplished, according to the present invention, by providing, in casting apparatus including a gas-permeable mold having a vertical passage with a lower open end for introducing molten metal into its mold cavity means, a crucible for holding molten metal with its surface positioned beneath the mold, power means for relatively moving the crucible and mold toward and away from one another for introducing molten metal from the crucible into the lower open end of the mold, and pressure means for applying a differential pressure to the mold and crucible to cause molten metal to fill the mold cavity means through the vertical passage, that improvement consisting of a rigid, permanently crimpable metal fill pipe sealingly connected to the lower open end of the vertical mold passage with its lower end extending vertically downwardly toward the crucible, and fill pipe crimping means positioned between the mold and crucible for selectively permanently crimping the fill pipe to close it after filling of the mold cavity means to prevent reverse flow of molten metal from the mold to the crucible.
According to the methods of the present invention, the fill pipe and mold are moved relatively toward the crucible to move the lower end of the fill pipe beneath the surface of the molten metal, a differential pressure is applied to the mold and crucible to cause molten metal to fill the mold cavity means through the fill pipe, and the fill pipe is thereafter permanently crimped to close it, preferably by welding, to prevent reverse flow of molten metal from the mold cavity means to the crucible as the mold and fill pipe are moved relatively away from the crucible.
US Referenced Citations (6)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 0580948 |
Nov 1977 |
SUX |
Non-Patent Literature Citations (1)
| Entry |
| "Drip Free Dispensing of Viscous Liquids", J. W. Grubb, Western Electric Technical Digest, No. 62, Apr. 1981, pp. 3-4. |
Continuation in Parts (1)
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Number |
Date |
Country |
| Parent |
583828 |
Feb 1984 |
|
Patent Grant
4589466
