Centrifugal method and apparatus for melting and casting of metal alloys

• US 4,763,717 A
• Filed: 04/18/1983
• Issued: 08/16/1988
• Est. Priority Date: 01/02/1975
• Status: Expired due to Fees

• Current Assignee: Pierre Lajoye
• Original Assignee: Pierre Lajoye
• Inventors: Lajoye, Pierre
• Primary Examiner(s): Lin, Kuang Y.
• Application Number:
  US06/484,355
• Time in Patent Office: 1,947 Days
• Field of Search: 164/114, 164/286, 164/303, 164/306, 164/254, 164/256, 164/258, 164/61, 164/62
• US Class Current: 164/258
• CPC Class Codes: B22D 13/04 of shallow solid or hollow bodies, e.g. wheels or rings, in moulds rotating around their axis of symmetry

Abstract

A method for melting and casting of metals and alloys and an apparatus using the method. The method consists of utilizing a compact assembly for melting and centrifugal casting of metals. The assembly includes a mold or chiller which is rotatable around a vertical axis. The mold communicates with a sealed lower housing containing an oven for the melting of the metal. The assembly is such that the interior chambers of both the oven and the mold are positioned in a vacuum during the entire time of the process of melting of the metal contained in the oven. The oven is movable vertically and is maintained in a position such that the lower extremity of a hollow vertical channel which feeds the mold, remains outside of the molten metal in the interior cavity of the oven when melting is occurring. Thus, the melting is accomplished entirely in a vacuum condition, thereby avoiding the formation of oxides or other chemical compounds.

Claims

1. An apparatus for the centrifugal casting of a metal, said apparatus comprising:

rotatable mold means having a central axis, said central axis being vertically disposed, said rotatable mold means further having an upper end and a lower end;

hollow shaft means formed at said lower end of said rotatable mold means and extending downwardly therefrom along said central axis;

a mold cavity formed in said rotatable mold means, said mold cavity being sealed;

a central passage formed in said hollow shaft means, said central passage having an upper end communicating with said mold cavity and a lower end remote from said upper end, said central passage extending downwardly along said central axis from said upper end to said lower end;

mold rotation means for selectively rotating said rotatable mold means about said central axis;

oven housing means disposed below said rotatable mold means for melting a quantity of metal introduced therein;

intermediate housing means disposed between said rotatable mold means and said oven housing means;

an oven cavity formed in said oven housing means, said oven cavity being sealed;

crucible means disposed within said oven cavity, such that a quantity of said metal to be melted may be placed in said crucible means, said crucible means being in communication with said oven cavity;

heating means, for heating said crucible means to thereby melt said quantity of metal to form molten metal;

first aperture means in said oven housing means, said first aperture means extending from said oven cavity to a location external of said oven housing means;

tube means interposed said hollow shaft means of said rotatable mold means and said oven housing means, said tube means having an upper end, a lower end opposite said upper end, and a channel means extending from said upper end to said lower end, said upper end of said tube means being interconnected with said hollow shaft means such that said channel means is in communication with said central passage, said lower end of said tube means being passed through said first aperture means in said oven housing means into said oven cavity, said lower end of said tube being disposed above said crucible means;

first rotatable sealing coupling means interposed said lower end of said tube means and said oven housing means, said first rotatable sealing coupling means forming a seal between said lower end of said tube means and said oven housing means to close said first aperture means, said first rotatable sealing coupling means further permitting said tube means to rotate relative to said oven housing means about said central axis when said mold rotation means is actuated to rotate said rotatable mold means;

a sealed chamber formed between said intermediate housing means and said oven housing means such that said sealed chamber surrounds a portion of said lower end of said tube means, said sealed chamber further surrounding said first rotatable sealing coupling means;

second aperture means in said intermediate housing means, said lower end of said tube means being passed progressively through said second aperture means, said sealed chamber, and said first aperture means into said oven cavity;

second rotatable sealing coupling means interposed said lower end of said tube means and said intermediate housing means, said second rotatable sealing coupling means forming a seal between said lower end of said tube means and said intermediate housing means to close said second aperture means, said second rotatable sealing coupling means further permitting said tube means to rotate relative to said intermediate housing means about said central axis when said mold rotation means is actuated to rotate said rotatable mold means;

displacement means selectively operable for relatively moving along said central axis, said lower end of said tube means and said crucible means, such as to enable selectively submerging said lower end of said tube means in said molten metal disposed in such crucible means as well as to enable selectively removing said lower end of said tube means for contact with said molten metal, said channel means being thereby selectively placeable in communication with said molten metal in said crucible means, said molten metal forming a liquid seal between said oven cavity and said channel means when said lower end of said tube means is submerged in said molten metal;

first pump means for selectively creating a first predetermined pressure level in each of said mold cavity, said central passage, said channel means and said oven cavity during the heating of said crucible means and prior to submerging said lower end of said tube means into said molten metal such that said mold cavity, said central passage, said channel means and said oven cavity are continuously maintained at said first predetermined pressure level until after said tube means has become submerged in said molten metal, said first predetermined pressure level being a vacuum pressure level, said first pump means being interconnected with said upper end of said rotatable mold means at a location adjacent said central axis such that said first pump means maintains said first predetermined pressure level in each of said mold cavity, said central passage and said channel means after said tube means has become submerged in said molten metal, thereby reducing the amount of vaporized metal in said mold cavity; and

second pump means for controllably introducing a quantity of a chemically inert pressurized gas into said oven cavity after said lower end of said tube means is submerged into said molten metal in said crucible means, said chemically inert pressurized gas being pressurized to a second predetermined pressure level, said second predetermined pressure level being greater than said first predetermined pressure level such that a pressure differential exists between said oven cavity and said mold cavity, said molten metal being advanced from said crucible means to said mold cavity along said channel means and said central passage by said pressure differential, said mold rotation means thereafter being actuated to disperse said molten metal centrifugally in said mold cavity such that said molten metal is forced under pressure into said mold cavity while said rotatable mold means is rotated to thereby form a centrifugal casting in said mold cavity;

said chemically inert gas being disposed in said oven cavity such that the quantity of ambient air passing through an leaks developed in said first rotatable sealing coupling means at the point whereat said tube means extends into said oven housing means, is minimized.

2. The apparatus of claim 1 further comprising valve means interposed said second pump means and said oven cavity for progressively varying the flow rate of said molten metal from said crucible means to said mold cavity during formation of said centrifugal casting to thereby feed shrinkage holes forming in said centrifugal casting as it cools.