Investment casting utilizing flexible wax pattern tool

Abstract

An investment casting process wherein the wax pattern tool (44) is flexible to facilitate removal of the tool from the cast wax pattern (52) even when the cast shape would otherwise require multiple pull planes. The flexible tool may include a flexible insert (42) precisely indexed to a surrounding coffin mold (40), and thereby to an enclosed ceramic core (10). Positioning pins (106) may extend from the flexible tool to make compliant contact against the core prior to a wax injection step. The surface of the resulting wax pattern may contain an engineered topography (36) replicated through the flexible surface from a master tool (12). The flexible tool may encase thermally conductive or magnetic particles (92), or other active device (96) such as a sensor or vibrator which is operable during wax injection.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit of the 8 Dec. 2009 filing date of U.S. provisional application No. 61 / 267,519 (attorney docket 2009P22785US), which is incorporated by reference in its entirety herein.FIELD OF THE INVENTION[0002]This invention relates generally to the field of investment casting, and more particularly, to using a flexible tool or mold to form a wax pattern as part of an investment casting process.BACKGROUND OF THE INVENTION[0003]Investment casting is one of the oldest known metal-forming processes, dating back thousands of years to when it was first used to produce detailed artwork from metals such as copper, bronze and gold. Industrial investment castings became more common in the 1940's when World War II increased the demand for precisely dimensioned parts formed of specialized metal alloys. Today, investment casting is commonly used in the aerospace and power industries to produce gas turbine components such as blades o...

AI Technical Summary

Benefits of technology

[0008]The present invention is part of an entirely new regiment for investment casting. As described and claimed herein, a flexible wax pattern mold may be formed as a hybrid tool having a flexible insert within a coffin mold. The flexible insert facilitates the removal of the wax pattern tool from the cast wax pattern by deforming the flexible insert around cast features that would otherwise require multiple pull planes for hard tooling. The flexible insert may be cast from a master tool that is machined from a relatively low cost, low hardness material such as aluminum or mild steel.

Problems solved by technology

Some desired surface topographies are so fine that they may not survive in the surface of the wax during subsequent handling and ceramic shell forming steps.

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