Turbine exhaust case and method of making

Abstract

A structural turbine exhaust case of a gas turbine engine, comprises inner and outer case portions; a bearing housing connected to the inner case portion for supporting a main spool of the gas turbine engine; and a plurality of airfoils extending between the inner and outer case portions, airfoils structurally connecting the inner case portion to the outer case portion.

1 . A method of welding an end of a sheet metal airfoil to an annular case of a gas turbine engine, comprising: 
 inserting the end of the airfoil into a matingly-profiled opening of the case wall; and    applying a weld fillet extending along an periphery of the profiled opening and fully penetrating through an entire thickness of the case wall, wherein the case wall thickness is adapted to permit said full penetration.    
     
     
         2 . The method as claimed in  claim 1  wherein said end of the airfoil protrudes through said opening by a predetermined amount to form a protrusion, the predetermined amount being an amount which will be substantially consumed in the weld, such that substantially no protrusion remains after welding is completed.  
     
     
         3 . The method as claimed in  claim 1  wherein the weld fillet penetrates through substantially an entire thickness of the sheet metal of the case.  
     
     
         4 . A method of fabricating a turbine exhaust case of a gas turbine engine, comprising: 
 providing inner and outer case portions with profiled openings therein;    providing a bearing housing for supporting a main spool of the gas turbine engine;    providing a plurality of sheet metal airfoils; and    brazing the bearing housing to the inner case portion and welding the respective airfoils at opposed ends thereof to the respective inner and outer case portions, thereby structurally connecting the inner and outer case portions to bear a load of the main spool of the engine supported by the bearing housing.    
     
     
         5 . A method as claimed in  claim 4  comprising steps of inserting one end of an airfoil into a corresponding profiled opening in the respective inner and outer case portions and forming weld penetrating through the an entire thickness of the respective case portions and penetrating through an entire thickness of the sheet metal of the airfoil.  
     
     
         6 . A method as claimed in  claim 5  wherein said end of the airfoil is inserted into the corresponding profiled opening from one side of the respective inner and outer case portions to have a predetermined portion of the airfoil protruding from the other side of the respective inner and outer case portions, the predetermined protruding portion being substantially consumed in weld.  
     
     
         7 . A method as claimed in  claim 6  wherein one of the laser beam and electron beam is applied to said end of the airfoil at said other side of the respective inner and outer case portions.  
     
     
         8 . A method of welding a profiled sheet metal element to a metal host having a matingly-profiled opening therethrough, the method comprising the step of: 
 inserting an end profiled sheet metal element into the matingly-profiled opening from a first face side of the host such that a portion of the element protrudes through the opening and extends a height above a second face side of the host; and    applying a weld fillet from the second face side along a periphery of the opening;    wherein the protrusion height is selected so that the protruding portion is substantially consumed during the step of applying a fillet weld.    
     
     
         9 . The method of  claim 8  wherein the metal host has a thickness between the first and second face sides, and wherein the thickness is selected such that the step of applying a fillet results in full penetration through the host substantially around the opening.