Controlled method for injection casing using a mold under vacuum, especially intended for aluminium or magnesium alloys and device for carrying out said method
First Claim
1. A process for injection casting parts, particularly thin walled parts made of metallic alloys, polymers and alloy fiber composites, comprising:
- placing inside a furnace a crucible containing a casting metal;
plunging an injection tube, arranged upon a plate covering the furnace, into the casting metal;
placing a mold on a support with the mold in fluid communication with the injection tube;
sealingly positioning a bell about the mold;
creating an equal vacuum level in both the mold and furnace without causing either the injection of the metal into the mold or the expulsion of the metal from the crucible;
filling the mold by pressurizing the furnace while maintaining pressure variations inside the furnace and the mold and speed variations of the metal inside the mold at any given instant at desired values based on a geometry of a part to be poured and a difference in height of the metal inside the crucible from the beginning of the filling of the mold to the given instant thereby causing a controlled injection of the metal into the mold while creating a pressure differential between the furnace and the bell;
bringing the bell to a pressure at least equal to atmospheric pressure while maintaining a difference in pressure between the furnace and the bell at least equal to said pressure differential;
maintaining the pressures in the furnace and the bell while the metal in the mold cools and solidifies; and
depressurizing the furnace and the bell to atmospheric pressure.
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Accused Products
Abstract
A device for injection casting includes a furnace within which is position a crucible, a bell mounted atop a table into which a mold is positioned and a tube interconnecting the crucible and the mold. A device is provided to sense the level of metal within the crucible; piping is provided into the bell and the furnace for controlling the respective pressures therein and various sensors are provided in the bell, mold, tube and furnace which sense various pressures and temperatures experienced within the device during the casting operation. These sensors provide signals to a control apparatus which controls the pressure inside the furnace in order to fill the mold with metal inside the crucible and regulates the speed and pressure inside the mold. A method of operating the device is also provided.
11 Citations
20 Claims
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1. A process for injection casting parts, particularly thin walled parts made of metallic alloys, polymers and alloy fiber composites, comprising:
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placing inside a furnace a crucible containing a casting metal; plunging an injection tube, arranged upon a plate covering the furnace, into the casting metal; placing a mold on a support with the mold in fluid communication with the injection tube; sealingly positioning a bell about the mold; creating an equal vacuum level in both the mold and furnace without causing either the injection of the metal into the mold or the expulsion of the metal from the crucible; filling the mold by pressurizing the furnace while maintaining pressure variations inside the furnace and the mold and speed variations of the metal inside the mold at any given instant at desired values based on a geometry of a part to be poured and a difference in height of the metal inside the crucible from the beginning of the filling of the mold to the given instant thereby causing a controlled injection of the metal into the mold while creating a pressure differential between the furnace and the bell; bringing the bell to a pressure at least equal to atmospheric pressure while maintaining a difference in pressure between the furnace and the bell at least equal to said pressure differential; maintaining the pressures in the furnace and the bell while the metal in the mold cools and solidifies; and depressurizing the furnace and the bell to atmospheric pressure. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of performing an injection casting operation comprising:
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placing a crucible adapted to house a casting metal inside a furnace; fluidly interconnecting the crucible with a mold; sensing the height of metal inside the crucible; simultaneously placing the mold and the furnace under an equal starting vacuum; filling the mold at a controlled rate by pressurizing the furnace to cause the metal to flow from the crucible to the mold; directly sensing a pressure inside the mold; sensing the quantity of the metal in the crucible by sensing the height of metal inside the crucible; governing the controlled rate and the pressure in the mold as a function of the sensed quantity of metal inside the crucible at the beginning of and throughout the filling of the mold; maintaining the pressures in the mold and the furnace while the metal in the mold is cooled and solidified; and depressurizing the furnace to atmospheric pressure. - View Dependent Claims (8, 9)
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10. An injection casting device comprising:
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a sealed furnace; a table; a bell sealed to said table and fluidly isolated from said furnace; a metal containing crucible located in said furnace; a tube fixed to one of said table and said bell and extending into said crucible; a mold located in said bell and open to said tube; means for simultaneously creating a vacuum in said bell and said furnace, said creating means including; at least one vacuum pump; a first pipe interconnected between said at least one vacuum pump and said bell; a second pipe interconnected between said at least one vacuum pump and said furnace; a first valve arranged in said first pipe; and a second valve arranged in said second pipe; pressure sensors for directly sensing a pressure in said mold and in said furnace respectively; means for continuously determining the height of metal inside the crucible; and means for controlling, based on signals received from said pressure sensor and said determining means and through at least said first and second valves, the pressure inside said mold and said furnace in order to fill said mold with metal from said crucible and to regulate a metal flowing speed and pressure inside said mold during filling thereof. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification