Contoured Metallic Casting Core

Abstract

A method for manufacturing an investment casting core uses a metallic blank having a thickness between parallel first and second faces less than a width and length transverse thereto. The blank is locally thinned from at least one of the first and second faces. The local thinning forms a taper on a leading portion of the RMC. The blank is through-cut across the thickness. The blank is inserted into the leading portion into a slot in a pre-formed ceramic core.

1 . A method for manufacturing an investment casting core from a metallic blank having a thickness between parallel first and second faces less than a width and length transverse thereto, the method comprising:
 locally thinning the blank from at least one of the first and second faces, the local thinning forming a taper on a leading portion of the RMC;   through-cutting the blank across the thickness; and   inserting the leading portion into a slot in a pre-formed ceramic core.   
     
     
         2 . The method of  claim 1  wherein:
 at least the through-cutting comprises at least one of stamping, laser cutting, liquid jet cutting, and EDM. 
 
     
     
         3 . The method of  claim 1  wherein:
 at least the locally thinning comprises at least one of EDM, ECM, MDP, and mechanical machining. 
 
     
     
         4 . The method of  claim 1  wherein:
 the through-cutting and the locally thinning are performed separately. 
 
     
     
         5 . The method of  claim 1  wherein:
 the through-cutting comprises forming a plurality of through-apertures. 
 
     
     
         6 . The method of  claim 1  wherein:
 the locally thinning comprises machining a main portion and leaving a thicker portion downstream of the main portion. 
 
     
     
         7 . The method of  claim 1  further comprising:
 coating the core. 
 
     
     
         8 . The method of  claim 1  wherein:
 the locally thinning comprises forming the taper by thinning both of the first and second faces. 
 
     
     
         9 . The method of  claim 8  wherein:
 the local thinning comprises essentially uniformly removing material from a pressure side along the taper and an intermediate portion downstream thereof and, along the suction side, removing material only from the leading portion. 
 
     
     
         10 . The method of  claim 1  wherein:
 the through-cutting forms apertures within the blank. 
 
     
     
         11 . A method for investment casting comprising:
 forming according to  claim 1  an investment casting core;   molding a pattern-forming material at least partially over the at least one investment casting core for forming a pattern;   shelling the pattern;   removing the pattern-forming material from the shelled pattern for forming a shell;   introducing molten alloy to the shell; and   removing the shell.   
     
     
         12 . The method of  claim 11  used to form a gas turbine engine component. 
     
     
         13 . The method of  claim 11  used to form a gas turbine engine airfoil wherein the core forms a trailing edge outlet slot. 
     
     
         14 . An investment casting core comprising:
 a metallic casting core element having:
 a tapered leading portion; 
 an intermediate portion downstream of the tapered leading portion; and 
 a trailing portion downstream of the intermediate portion and thicker than the intermediate portion; and 
   a ceramic casting core having a slot receiving the leading portion.   
     
     
         15 . The investment casting core of  claim 14  wherein:
 along the leading portion and intermediate portion, a pressure side surface has essentially continuous concave curvature; and 
 along a suction side surface, the intermediate portion has essentially continuous convex curvature and the leading portion has discontinuous curvature so as to provide the taper.