US 5,465,780 A · Laser machining of ceramic cores

Abstract

A method is disclosed for producing a hollow airfoil, specifically, a blade or vane for a gas turbine engine, which is formed with a complex interior for cooling purposes. Broadly, the method comprises the steps of molding a green ceramic core having outer surfaces generally contoured to produce the intended interior surfaces of the completed airfoil, heating the green ceramic core to a sufficient extent to produce a fired core, and operating on the fired core with a laser to modify the characteristics of the fired core. Use of the laser enables the formation of detailed features having a transverse dimension less than approximately 0.020 inches. Specific operations may include labeling, trimming, cutting, drilling either by punching or trepanning, etching or milling, and glazing or strengthening. In another embodiment of the invention, a layer is produced on the core surface having a very high surface energy to promote the flow of the casting alloy around the core within the mold.

Claims62

Dependent claims

A method of producing a core for making a hollow blade comprising the steps of:

(a) molding a green ceramic core having outer surfaces generally contoured to produce the intended interior surfaces of the completed blade;
(b) heating the green ceramic core to a sufficient extent to produce a fired core;
and
(c) operating on the fired core with a laser to modify the characteristics of the fired core.

1 more element

A method of making a hollow blade comprising the steps of:

(a) molding a green ceramic core having outer surfaces generally contoured to produce the intended interior surfaces of the completed blade;
(b) heating the green ceramic core to a sufficient extent to produce a fired core;
(c) operating on the fired core with a laser to modify the characteristics of the fired core;
(d) inserting the modified fired core into a wax injection mold having the negative contour of a desired blade;
(e) injecting molten wax into the wax injection mold to form a wax mold/core combination;
(f) removing the wax mold/core combination from the wax injection mold;
(g) generously coating the wax mold/core combination with a ceramic slurry;
(h) causing the ceramic slurry applied in step (g) to harden so as to form an outer shell;
(h) heating the outer shell to melt the wax of the wax mold/core combination within the interior of the outer shell;
(i) draining off the melted wax from the interior of the outer shell;
(j) pouring molten alloy into the interior of the outer shell to thereby fill the cavity defined by the interior surfaces of the outer shell and the surfaces of the fired core;
(k) allowing the alloy to solidify to form a casting having a desired external surface with the desired contour;
and
(l) leaching out the fired core from the interior of the casting substantially resulting in the desired hollow blade.

11 more elements

Dependencies are inferred from the claim text.

Laser machining of ceramic cores

Life of this patent

Laser machining of ceramic cores

Life of this patent

Abstract

Claims62