Method for manufacturing a stator core for a dynamoelectric machine

Abstract

A cylindrical laminated body is prepared by winding into a helical shape a continuous first sheet formed by press-punching from a thin first magnetic steel sheet material. A second sheet having a predetermined length is prepared by press-punching from a thicker second magnetic steel sheet material. Next, chamfered portions are formed on edge portions of second recess portions by chamfering the second sheet. Then, the second sheet is bent into an annular shape and the second sheets bent into the annular shape are stacked on both axial ends of the laminated body and integrated by laser welding.

What is claimed is:  
     
         1 . A method for manufacturing a stator core for a dynamoelectric machine, said method comprising the steps of: 
 preparing a cylindrical laminated body by preparing a continuous first sheet in which first recess portions are formed at a predetermined spacing by press-punching from a strip-shaped first magnetic steel sheet material and winding said first sheet into a helical shape such that said first recess portions are superposed in an axial direction;    preparing a second sheet having a predetermined length in which second recess portions are formed at a predetermined spacing by press-punching a second magnetic steel sheet material having a sheet thickness greater than that of said first magnetic steel sheet material;    bending said second sheet into an annular shape;    stacking said second sheets bent into the annular shape on both axial ends of said laminated body such that said second recess portions are superposed on said first recess portions in an axial direction; and    integrating said laminated body and said second sheets stacked together by applying several strips of welding on an outer circumferential surface of said laminated body and said second sheet so as to extend from a first end to a second end in an axial direction.    
     
     
         2 . The method for manufacturing a stator core for a dynamoelectric machine according to  claim 1 , further comprising the step of joining together abutted portions of first and second end surfaces of said second sheets bent into the annular shape before the step of stacking said second sheets bent into the annular shape on said laminated body.  
     
     
         3 . The method for manufacturing a stator core for a dynamoelectric machine according to  claim 1 , wherein abutted portions of said second sheets bent into the annular shape are joined together simultaneously by said welding during the step of integrating said laminated body and said second sheets.  
     
     
         4 . The method for manufacturing a stator core for a dynamoelectric machine according to  claim 1 , further comprising the step of forming an chamfered portion on an edge portion of said second recess portions by chamfering said second sheet before the step of bending said second sheet into the annular shape.  
     
     
         5 . The method for manufacturing a stator core for a dynamoelectric machine according to  claim 4 , further comprising the step of joining together abutted portions of first and second end surfaces of said second sheets bent into the annular shape before the step of stacking said second sheets bent into the annular shape on said laminated body.  
     
     
         6 . The method for manufacturing a stator core for a dynamoelectric machine according to  claim 4 , wherein abutted portions of said second sheets bent into the annular shape are joined together simultaneously by said welding during the step of integrating said laminated body and said second sheets.