Low-pressure casting method and low-pressure casting apparatus

• US 4,425,958 A
• Filed: 11/16/1981
• Issued: 01/17/1984
• Est. Priority Date: 12/23/1980
• Status: Expired due to Fees

• Current Assignee: Egro AG
• Original Assignee: Egro AG
• Inventors: Zimmermann, Max, Isler, Eugen, Luthy, Hans, Meier, Ewald
• Primary Examiner(s): Hampilos, Gus T.
• Assistant Examiner(s): Seidel, Richard K.
• Application Number:
  US06/322,063
• Time in Patent Office: 792 Days
• Field of Search: 164/113, 164/119, 164/137, 164/306, 164/309, 164/312, 164/316, 164/341-343, 164/72, 164/267
• US Class Current: 164/119
• CPC Class Codes: B22D 18/04 Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
• CPC Class Codes: B22D 33/00 Equipment for handling moulds

Abstract

With low-pressure or die-casting methods there frequently occur leaks during the transfer of the molten metal from the metal containing basin or vessel to the mold. These leaks often lead to serious accidents and related operating interruptions. According to the invention these problems are solved by a casting method, wherein all movements of the mold occur in a vertical plane. With a preferred embodiment of apparatus for the performance of the method the mold is placed in a positive or form-locking manner with its casting or pour opening upon the casting hole of the metal containing vessel or basin and pressed against the latter in a fluidtight fashion by means of a pneumatic lifting cylinder. This affords the advantage of a simple connection of the mold with the basin and without requiring a coupling mechanism, and, additionally, the heating of the riser or up tube and/or immersion tube can be omitted, which otherwise conventionally was performed by gas heating.

Claims

1. A low-pressure casting method for the casting of cast pieces within a displaceably arranged mold containing mold halves and a casting opening, comprising the steps of:

providing a substantially pressure-tight closed vessel containing a cover plate at its upper side equipped with a casting hole;

providing within said vessel which contains a molten metal a gas chamber above the molten metal;

displacing said mold in a substantially vertical plane prior to casting;

said step of displacing said mold including lowering said mold together with its casting opening onto said casting hole of said metal-containing vessel;

placing said lowered mold with its casting opening into form-locking alignment with said casting hole of said vessel;

pressing said mold onto the cover plate of said vessel;

applying a gas pressure to said gas chamber to force the molten metal through the casting hole of the vessel and through the casting opening of the mold into the mold;

solidifying the cast piece formed in the mold;

venting the gas chamber following the solidification of the cast piece in the mold;

then further displacing said mold in said substantially vertical plane;

lifting the mold in a substantially vertical direction off of the vessel following venting of the gas chamber;

transporting the lifted mold in a substantially horizontal linear direction to a stripping station;

opening said mold at the stripping station;

removing the cast piece from the mold;

further displacing the mold following removal of the cast piece in a substantially linear direction to a washing, drying and finishing station;

rotating the mold halves of the mold within said vertical plane through an angle of approximately 90°

in order to open the mold; and

lowering the mold halves at the location of a parting plane thereof such that frontal surfaces of the opened mold halves are lowered and immersed into a cooling and finishing emulsion bath at the washing station.

2. The low-pressure casting method as defined in claim 1, including the steps of:

turning the mold with the mold halves open into an inclined position prior to casting;

inserting a casting core into at least one of the open mold halves; and

closing the mold and turning the closed mold back into a substantially horizontal position.

3. An apparatus for the low-pressure casting of cast pieces within a displaceably arranged mold possessing mold halves and a casting opening, comprising:

a substantially pressure-tight closed vessel provided with a cover plate at its upper side containing a casting hole;

said pressure-tight vessel containing a molten metal therein which is to be cast and a gas chamber above the molten metal;

track means;

a carriage for supporting the mold;

means for displaceably mounting said carriage at said track means;

said displaceably mounting means including structure for displacing said mold towards said pressure-tight vessel in order to press said mold onto said cover plate of said vessel and with said casting opening of the mold in form-locking alignment with said casting hole of said vessel in an essentially leakage-free manner and without the use of any sealing means interposed between the casting opening and the casting hole;

said structure of said displaceably mounting means enabling said mold to be moved in a substantially vertical plane prior to the casting operation;

said structure comprises a fluid-operated displacement device interposed between said carriage and said mold; and

said displacement device comprises at least one fluid-operated lifting cylinder and two pivoting cylinders acting upon a double-arm lever.

4. The apparatus as defined in claim 3, further including:

mold supports provided for the mold halves of said mold; and

a locking cylinder provided for each of said mold halves.

5. The apparatus as defined in claim 4, further including:

column guide means for substantially parallely guiding said mold halves.

6. The apparatus as defined in claim 3, wherein:

said structure comprises a displacement device; and

column guide means for vertically guiding said displacement device.

7. The apparatus as defined in claim 3, further including:

means defining a mold stripping station;

means defining a washing, drying and finishing station; and

said track means being guided over said vessel, said stripping station and said washing drying and finishing station.