Pressurized squeeze casting apparatus and method and low pressure furnace for use therewith

• US 5,887,642 A
• Filed: 07/14/1998
• Issued: 03/30/1999
• Est. Priority Date: 06/16/1995
• Status: Expired due to Fees

• Current Assignee: James B. Thomas
• Original Assignee: James B. Thomas
• Inventors: Thomas, deceased, Robert Anthony, Thomas, executor, by James B., Hale, Roger
• Primary Examiner(s): Lin, Kuang Y.
• Application Number:
  US09/114,762
• Time in Patent Office: 259 Days
• Field of Search: 164/120, 164/319, 164/113, 164/136
• US Class Current: 164/319
• CPC Class Codes: B22D 18/02 Pressure casting making use of mechanical pressure devices, e.g. cast-forging B22D18/04 takes precedence
• CPC Class Codes: B22D 18/04 Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould

Abstract

A pressurized squeeze casting apparatus and method for casting articles includes densifying means for mechanically applying force to a die assembly to compress and densify the molten metal material into a solid article having a near net shape. A shutoff member is provided to seal the interior cavity at the juncture of the runner and the cavity after the cavity is filled with molten metallic material and prior to densification. A low pressure furnace provides a supply of molten metallic material. The outlet from the furnace is biased into engagement with the runner by the gas pressure in the low pressure furnace to ensure a fluid tight connection between the furnace and the runner.

Claims

1. A pressurized squeeze casting apparatus for receiving molten metal material and compressing and densifying the molten metal material as the molten metal material is solidified into a solid metallic article having a predetermined near net shape comprising a first die section having a planar surface, a first mold portion supported by said first die section adjacent to said planar surface and defining a portion of an interior cavity, a second die section having a planar surface, a second mold portion supported by said second die section adjacent to said planar surface and defining a second portion of said interior cavity, said first die section and said first mold portion being movable relative to said second die section and said second mold portion between an open position in which said planar surface of said first die section is spaced apart from said planar surface of said second die section and a closed position in which said planar surface of said first die section engages said planar surface of said second die section and said portion of said interior cavity defined by said first mold portion is aligned with said second portion of said interior cavity defined by said second mold portion to substantially define an interior cavity shaped substantially to form the solid metallic article, a runner at least partially located on said planar surface of one of said die sections for introducing the molten metal material into said interior cavity when said first and second mold portions are in said closed position, densifying means for effecting relative movement of said first mold portion and said second mold portion to reduce the volume of said interior cavity after said interior cavity has been filled by said molten metal material to compress and densify the molten metal material in said interior cavity, said first mold portion being movable between a fill position in which the interior cavity is filled with molten metal material and wherein the interior cavity volume is greater than the solid metallic article to be cast and a densifying position, wherein the interior cavity volume and the volume of the molten metal material therein is reduced from the volume at the fill position to a volume substantially equal in size to the solid metallic article to be cast, and an elongate molten material shutoff element having a longitudinal axis which is substantially perpendicular to said planar surfaces of said first and second die sections for preventing the flow of molten metal material between said runner and said interior cavity when said densifying means effects reduction of the volume of said interior cavity, said molten material shutoff element being movable in a direction substantially parallel to said longitudinal axis relative to said first and second die sections between a retraced position in which said molten material shutoff element is retracted from said runner and said molten metal material flows between said runner and said interior cavity, and a sealing position in which said molten material shutoff element extends into and seals said runner to prevent said molten metal material from flowing between said runner and said interior cavity, said shutoff element having an inner side surface for engaging molten metal material in said interior cavity to in part define said interior cavity when said shutoff element is in said sealing position and outer side surface means for engaging molten metal material in said runner when said shutoff element is in said sealing position, and motor means for moving said shutoff element relative to said first and second die sections to said sealing position prior to operation of said densifying means to effect relative movement of said first mold portion and said second mold portion.

2. A pressurized squeeze casting apparatus as defined in claim 1 wherein said molten metal shutoff element has a pointed surface which extends in a direction substantially parallel to said longitudinal axis of said molten material shut-off element for engaging said molten metal material in said runner adjacent to said interior cavity when said shutoff element is moved in a direction substantially parallel to said longitudinal axis from said retracted position to said sealing position and for sealing the runner to prevent the flow of molten metal between said runner and said interior cavity, said pointed surface being located on said shutoff element adjacent to said inner side surface on said shutoff element which cooperates with said mold portion to define said interior cavity.

3. A pressurized squeeze casting apparatus for receiving molten metal material and compressing and densifying the molten metal material as the molten metal material is solidified into a solid metallic article having a predetermined near net shape comprising a first die section having a planar surface on which a first mold portion shaped to define a portion of the metallic article is located, a second die section having a planar surface on which a second mold portion shaped to define another portion of the metallic article is located, said second mold portion and said first mold portion being relatively movable in a direction substantially perpendicular to said planar surfaces between an open position in which said planar surface of said first die section is spaced apart from said planar surface of said second die section and a closed position in which said planar surface of said first die section engages said planar surface of said second die section, said first mold portion and said second mold portion being shaped and cooperating to define a substantial portion of an interior cavity shaped substantially to form the metallic article to be cast when said first and second mold portions are in said closed position, a runner located on at least one of said planar surfaces of said first and second die sections for introducing a supply of molten metal material to said interior cavity, densifying means for forcibly moving said first mold portion relative to said second mold portion to reduce the volume of said interior cavity after said interior cavity has been filled with molten metal material to compress the molten metal material in said interior cavity across substantially the entire face of the metallic article to be cast, and flow prevention means for preventing the flow of molten metal material between said runner and said interior cavity when said densifying means effects reduction of the volume of said interior cavity, said first mold portion when said first and second mold portions are in said closed position being movable between a fill position, wherein the interior cavity volume is greater than the volume of the solid metallic article to be cast and a densifying position, wherein the interior cavity volume is reduced by said densifying means to equal the volume of the solid metallic article, said flow prevention means includes a molten material shutoff element having a longitudinal axis disposed substantially perpendicular to said planar surfaces of said first and second die sections for sealing said runner, said shutoff element being movable in a direction substantially parallel to said longitudinal axis from a retracted position in which said shutoff element is retracted from said runner and said molten metal material flows between said runner and said interior cavity to a sealing position in which said shutoff element seals said runner prior to operation of said densifying means to move said first mold portion relative to said second mold portion to prevent said molten metal material from flowing between said runner and said interior cavity, during operation of said densifying means.