Method for Producing Hollow Blades

Abstract

A method for producing hollow blade blades, in particular for gas turbines such as aircraft jet engines is provided. At least three elements ( 20, 21, 22 ) are located one on top of the other in a sandwich structure, are joined together at least in sections by diffusion welding and are then superplastically formed by expansion in such a way that a first element ( 20 ) forms a first external wall of the hollow blade to be produced, a second element ( 22 ) forms a second external wall of the hollow blade to be produced and a third element ( 21 ) forms a central element running between the two external walls of the hollow blade to be produced. At least one nick-minimizing structure is introduced into the first element ( 20 ) and the second element ( 22 ), which form the two external walls of the hollow blade to be produced, before said elements are arranged together with the third element ( 21 ) in the sandwich structure.

1 - 11 . (canceled) 
     
     
         12 . A method for manufacturing hollow blades, comprises:
 providing at least a first element, a second element, and a third element, an inner side of each of the first and second elements having a planar recess;   arranging the first, second and third elements one over another in a sandwich-type structure;   joining the first, second and third elements to one another at least in portions thereof by diffusion welding;   superplastically deforming the sandwich-type structure via an inflation processes, such that the first element forms a first outer wall of a hollow blade to be manufactured, the second element forms a second outer wall of the hollow blade to be manufactured, and the third element forms a middle element of the hollow blade to be manufactured which extends in between the first and second outer walls, and a portion of the third element is spaced apart from the planar recesses.   
     
     
         13 . The method of  claim 12 , wherein the inner side of the first element faces one side of the third element, and the inner side of the second element faces an opposite side of the third element. 
     
     
         14 . The method as recited in  claim 13 , wherein the planar recesses extend over a portion of the inner sides of the first element and of the second element., such that a middle section of the first element and a middle section of the second element has a smaller material thickness than lateral sections of the first and second elements respectively. 
     
     
         15 . The method as recited in  claim 14 , wherein, between the middle section and the lateral sections of each of the first and second elements, the respective recesses have a continuous or stepless transitional profile. 
     
     
         16 . The method as recited in  claim 15 , wherein, in cross section, the continuous or stepless transitional profile has a circular or elliptical form. 
     
     
         17 . The method as recited in  claim 16 , wherein the recesses are introduced into the inner sides of the first element and of the second element, respectively, by milling. 
     
     
         18 . The method as recited in  claim 13 , wherein the pressure required for diffusion welding is supplied such that, during the diffusion welding process, the first element and the second element are pressurized in the area of the or of each continuous or stepless transitional profile such that, following the diffusion welding in the area of the or of each transitional profile, a groove space is formed. 
     
     
         19 . The method as recited in  claim 18 , wherein the pressure is supplied by a mechanical press.