Rotor end band

Abstract

An end band and method of forming an end band for a rotor. The end band includes a hollow cylindrical band, wherein at least a portion of the band has a grain flow in a direction parallel to the hoop stress of the band. The end band also includes at least a portion having a grain flow in a direction perpendicular to the hoop stress of the band.

1 . An end band comprising:
 a hollow cylindrical band wherein at least a portion of the band has a grain flow in a direction parallel to a hoop stress of the band and at least a portion of the band has a grain flow in a direction perpendicular to the hoop stress of the band.   
     
     
         2 . The end band according to  claim 1 , wherein the hollow cylindrical band is made from a sheet of material having a uniform grain flow. 
     
     
         3 . The end band according to  claim 1 , wherein the hollow cylindrical band is made from Inconel. 
     
     
         4 . The end band according to  claim 2 , wherein the hollow cylindrical band has a grain size comparable or smaller than a grain size of an end band made from bar stock of the same material. 
     
     
         5 . The end band according to  claim 4 , wherein the hollow cylindrical band has a grain size number of approximately 9. 
     
     
         6 . An rotor assembly comprising:
 at least one lamination including a plurality of teeth;   at least one insulation ring having a plurality of teeth matching and aligned with the teeth of the lamination, wherein the at least one insulation ring is attached to the lamination;   slot insulation disposed between the teeth of the lamination and the teeth of the insulating ring;   a plurality of wire windings wrapped around the teeth of the lamination and insulation ring; and   at least one hollow cylindrical end band surrounding the rotor assembly, wherein at least one portion of the end band has a first grain flow in a direction parallel to a hoop stress of the end band and at least one portion of the end band has a second grain flow in a direction perpendicular to the hoop stress of the end band.   
     
     
         7 . The rotor assembly according to  claim 6 , wherein the hollow cylindrical end band is made from a sheet of material having a uniform grain flow. 
     
     
         8 . The rotor assembly according to  claim 6 , wherein the hollow cylindrical end band is made from Inconel. 
     
     
         9 . The rotor assembly according to  claim 6 , wherein the hollow cylindrical end band has a grain size comparable or smaller than a grain size of an end band made from bar stock of the same material. 
     
     
         10 . The rotor assembly according to  claim 6 , wherein the hollow cylindrical end band has a grain size number of approximately 9. 
     
     
         11 . A method for manufacturing an end band comprising:
 hydroforming a hollow cylinder having an open end and a closed end;   stress-relieving the hollow cylinder;   aging the hollow cylinder; and   removing the closed end of the hollow cylinder to form an end band.   
     
     
         12 . The method for manufacturing an end band according to  claim 11 , wherein a flat sheet of material is used to hydroform the hollow cylinder. 
     
     
         13 . The method for manufacturing an end band according to  claim 12 , wherein the material is Inconel. 
     
     
         14 . The method for manufacturing an end band according to  claim 11 , wherein a height of the hollow cylinder is substantially the same as a width of the end band. 
     
     
         15 . The method for manufacturing an end band according to  claim 11 , wherein a height of the hollow cylinder is substantially the same as a width of a plurality of end bands. 
     
     
         16 . The method for manufacturing an end band according to  claim 11 , wherein the closed end of the hollow cylinder is removed by machining. 
     
     
         17 . The method for manufacturing an end band according to  claim 11 , wherein the hollow cylinder is aged to reduce internal stresses in the band. 
     
     
         18 . The method for manufacturing an end band according to  claim 11 , wherein the hollow cylinder is stress-relieved to control the growth of the grain size. 
     
     
         19 . The method for manufacturing an end band according to  claim 11 , wherein at least one portion of the end band has a first grain flow in a direction parallel to a hoop stress of the end band and at least one portion of the end band has a second grain flow in a direction perpendicular to the hoop stress of the end band.