Dynamo-electric machine stator stack forming methods and apparatus

Abstract

Hollow cylindrical dynamo-electric machine stator cores may be made by superimposing at least two strips of core material to produce a composite strip. One or more of the strips may be run through a pressure roller structure prior to super-positioning of the strips. The composite strip is coiled helically to produce the hollow cylindrical stator core. By pressure rolling at least one strip, the internal diameter of the stator core can be adjusted to reduce irregularities. By superimposing strips prior to coiling, thinner strips can be used without requiring the stator forming machine to operate longer or faster to produce stator cores of a given size. The pressure rolling aspects of the invention are also applicable to coiling apparatus that uses only a single strip. Stator cores may also be made by coaxially assembling and joining two coils with a hollow annular lamination disposed between the two axially spaced coils.

The Invention claimed is:  
     
         1 . A method of forming a hollow cylindrical dynamo-electric machine stator core comprising: 
 supplying first and second strips of source material;    applying pressure to the first strip in order to modify an axial length dimension of the first strip;    helically coiling the first strip to produce a first helical coil;    helically coiling the second strip to produce a second helical coil; and    assembling the first and second helical coils substantially coaxially with one another and axially spaced from one another by an annular lamination which is also substantially coaxial with the first and second coils to produce the hollow cylindrical dynamo-electric machine stator core.    
     
     
         2 . The method defined in  claim 1  wherein the applying comprises: 
 passing the first strip through a nip between pressure rollers.  
 
     
     
         3 . The method defined in  claim 1  further comprising: 
 measuring a dimension of the first helical coil; and  
 controlling the pressure to the first strip based at least in part on the dimension.  
 
     
     
         4 . The method defined in  claim 3  wherein the dimension is an internal diameter of the first helical coil.  
     
     
         5 . The method defined in  claim 1  further comprising: 
 applying pressure to the second strip in order to modify an axial length dimension of the second strip.  
 
     
     
         6 . A method of forming a hollow cylindrical dynamo-electric machine stator core comprising: 
 supplying first and second strips of source material;    applying pressure to at least one of the first and second strips in order to modify an axial length dimension of the one strip;    superimposing the first and second strips on one another to produce a composite strip; and    helically coiling the composite strip to produce the hollow cylindrical dynamo-electric machine stator core.    
     
     
         7 . The method defined in  claim 6  wherein the applying comprises: 
 passing the one strip through a nip between pressure rollers.  
 
     
     
         8 . The method defined in  claim 6  further comprising: 
 measuring a dimension of the stator core; and  
 controlling the pressure based at least in part on the dimension.  
 
     
     
         9 . The method defined in  claim 8  wherein the dimension is an internal diameter of the stator core.  
     
     
         10 . A method of forming a hollow cylindrical dynamo-electric machine stator core comprising: 
 supplying first and second strips of source material;    applying pressure to the first strip in order to modify an axial length dimension of the first strip;    applying pressure to the second strip in order to modify an axial length dimension of the second strip;    superimposing the first and second strips on one another to produce a composite strip; and    helically coiling the composite strip to produce the hollow cylindrical dynamo-electric machine stator core.