US 2003/0205351 A1 · Method of making precision castings using thixotropic materials

Abstract

Precision castings requiring a fine finish and having complex internal geometries can be produced by casting a semi-solid thixotropic metal alloy within or about a melt-away metal component in the form of a core and/or a die insert that has a lower melting point than the solid-to-semi-solid transition temperature of the thixotropic alloy The thixotropic alloy may be cast, e.g., by thixocasting, rheocasting, sub liquidus casting. Then, after the alloy solidifies to form a casting with a captured melt-away component, the component is melted from the casting, preferably using a liquid bath. Process robustness, speed, and versatility can be enhanced by coating the component with a thin, uniform, abrasion-resistant, and thermally resistant coating that prevents excessive heat from being transferred to the component from the alloy and that prevents the component from alloying with the casting.

Claims26

Dependent claims

A precision casting process comprising:

(A) placing a metal core in a mold while retaining a die cavity between said core and an inner surface of said mold;
then
(B) forming a semi-solid thixotropic alloy and filling said die cavity with the semi-solid thixotropic alloy at a temperature higher than a melting point of the metal of said core;
then
(B) allowing said shot to cool and solidify, thereby forming a casting;
then
(C) melting said core from said casting.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application

10/438,954Filed 15 May 2003

Priority

20 Oct 1997

Published

6 Nov 2003

Term ends

Not estimatedThe source records don’t support an estimate.

Classification10 codes

B22C 3/00
Selection of compositions for coating the surfaces of moulds, cores, or patterns
B22C 1/00
Compositions of refractory mould or core materials
B22C 9/10
Moulds or cores ; Moulding processes: cores; Manufacture or installation of cores
B22D 17/007
Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure: semi-solid pressure die…

Family

Application60/062,582Us provisional application · filed 20 Oct 1997

Application09/529,647Continuation in part · filed 17 Apr 2000

Application09/529,647A 371 of international · filed 17 Apr 2000

Application10/438,954Continuation in part · filed 15 May 2003

US 6,564,856 B1Related patent

US 6,962,189 B2Related patent

US 2003/0205351 A1This patent

From the US filing history. Foreign family members aren’t listed.

Method of making precision castings using thixotropic materials

Life of this patent

Method of making precision castings using thixotropic materials

Life of this patent

Abstract

Claims26