Multi-shot casting

• US 9,687,910 B2
• Filed: 12/13/2013
• Issued: 06/27/2017
• Est. Priority Date: 12/14/2012
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Bullied, Steven J., Shah, Dilip M., Cetel, Alan D., Marcin, John J.
• Primary Examiner(s): Kerns, Kevin P
• Assistant Examiner(s): HA, STEVEN S
• Application Number:
  US14/651,926
• Publication Number:
  US 20150328681A1
• Time in Patent Office: 1,292 Days
• CPC Class Codes: B22D 19/16 for making compound objects cast of two or more different metals, e.g. for making rolls for rolling mills casting compound ingots B22D7/02
• CPC Class Codes: B22D 27/045 Directionally solidified castings
• CPC Class Codes: F01D 5/147 Construction, i.e. structural features, e.g. of weight-saving hollow blades F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18
• CPC Class Codes: F05D 2230/211 by precision casting, e.g. microfusing or investment casting

Abstract

An alloy part is cast in a mold (280) having a part forming cavity (292, 294, 296). The method comprises pouring a first alloy into the mold. The pouring causes: a surface (550) of the first alloy in the part forming cavity to raise relative to the part forming cavity; a branch flow of the poured first alloy to pass upwardly through a first portion (304) of a passageway; and the branch flow to pass downwardly through a second portion (310), of the passageway; solidifying some of the first alloy in the passageway to block the passageway while at least some of the first alloy in the part forming cavity remains molten. A second alloy is poured into the mold atop the first alloy and solidified.

Claims

1. The prior art, either taken alone or in combination, fails to teach

a branch flow of the poured first alloy to pass upwardly through a first portion of a passageway;

and

the branch flow to pass downwardly through a second portion of the passageway;

solidifying some of the first alloy in the passageway to block the passageway while at least some of the first alloy in the part-forming cavity remains molten;

pouring a second alloy into the mold atop the first alloy; and

solidifying the second alloy.

2. The method of claim 1 wherein:

the pouring of the first alloy terminates before the blocking of the passageway.

3. The method of claim 1 wherein:

the passageway has an enlarged reservoir portion (302) distally of or formed by the second portion (310).

4. The method of claim 1 wherein:

the mold is progressively cooled to provide an upwardly moving solidification front (552) which passes through the first alloy to the second alloy to completely solidify the article.

5. The method of claim 1 wherein:

a boundary (540) between respective regions formed by the first alloy and the second alloy is determined by the position of a junction (308, 314) of the passageway first portion and passageway second portion.

6. The method of claim 1 wherein:

the first alloy and second alloy are introduced through a downsprue (400) which telescopes (402, 404) between first and second conditions.

7. The method of claim 1 wherein:

the first alloy and second alloy are introduced through the same port.

8. The method of claim 1 wherein:

the first alloy is bottom-fed via a downsprue; and

the second alloy is top-fed.

9. The method of claim 1 wherein:

a crystalline structure propagates across a transition from the first alloy to the second alloy.

10. The method of claim 9 wherein:

the crystalline structure is initiated by a grain starter (298).

11. The method of claim 1 wherein the part is a blade and the part-forming cavity comprises:

a root portion (292) for casting an attachment root of the blade; and

an airfoil portion (296) for casting an airfoil of the blade, the airfoil having a first end and a second end and a span between the first end and the second end.

12. The method of claim 1 wherein:

there are no additional pours.