Blade

Abstract

Reduction in weight is an important factor with respect to turbine engines used in aircraft. Blades ( 20 ) used in such turbine engines may fragment such that it is necessary that the containment casing ( 42 ) can resist such fragmentation. Root portions of blades are generally less deformable and therefore require conventionally more robust containment casings. Use of super plastically formed blades allows provision of slots ( 4, 14, 24, 46 ) in the root portion which facilitate fragmentation and deformation by the root portion under impact reducing the necessity for greater reinforcement of the containment casing. The slots ( 4, 14, 24, 24, 46 ) are created in a membrane utilised for web reinforcement of the blade rather than through intrusive drilling and cutting processes which may introduce machining stresses into their creation and potential tool loss within the high value blade. Additionally, by providing such slots ( 4, 14, 24, 46 ) it will be appreciated that the cavity formed within the blade may be sealed without additional machining or other processes.

1 . A blade for a turbine engine, the blade comprising a super plastically formed sandwich comprising a concave wall and a convex wall with a cavity membrane therebetween, the walls and cavity member are secured together by bonding about their edges in order to define a cavity therebetween when subject to a super plastic deformation process, the blade wherein the membrane incorporates slots which extend towards the cavity once formed by super plastic deformation. 
   
   
       2 . A blade as claimed in  claim 1  wherein the slots are flat. 
   
   
       3 . A blade as claimed in  claim 1  wherein the slots are of differing length. 
   
   
       4 . A blade as claimed in  claim 1  wherein the slots extend below a release plane for the blade. 
   
   
       5 . A blade as claimed in  claim 1  wherein the cavity is sealed. 
   
   
       6 . A blade as claimed in  claim 1  wherein the slots extend into open passage engagement with the cavity. 
   
   
       7 . A blade as claimed in  claim 1  wherein the slots do not extend into open passage engagement with the cavity. 
   
   
       8 . (canceled) 
   
   
       9 . A method of making a blade for a turbine engine, the method comprising taking two wall panels to be formed respectively as a concave wall and a convex wall in the blade and placing a membrane panel between them so that by superplastic deformation a blade is formed with a cavity between the walls, the method wherein prior to sandwiching the membrane panel between the walls, slots are formed in the membrane at positions and in configurations to extend towards the cavity once formed by the superplastic deformation process. 
   
   
       10 . A method as claimed in  claim 9  wherein the walls and membrane are secured together about their edges by a diffusion bonding process. 
   
   
       11 . A method as claimed in either of  claim 9  wherein the slots are formed in the blade at a position whereby the slots facilitate deformation of a root portion of the blade. 
   
   
       12 . (canceled) 
   
   
       13 . (canceled)