Unit core of motor and method for manufacturing the same

Abstract

Disclosed is a method manufacturing a unit core. The unit core is opposite to the neighboring unit core on an electric steel plate in orientation, and its unit yoke has an elongated end extending from a central line connecting a center of a tooth to a center of a core formed by interconnecting a plurality of the unit cores, to be opposite to the elongated end of the unit yoke of the neighboring unit core in orientation. This arrangement of the unit cores on the electric steel plate reduces a size of a scrap remaining after the unit cores are punched from the electric steel plate, thereby reducing the production cost of the unit core.

What is claimed is:  
     
         1 . A method for manufacturing a unit core of a motor comprising a unit yoke formed in a circumferential direction and a tooth radially protruding from the unit core, a plurality of said unit cores being interconnected so as to form a core of the motor, 
 wherein a pair of lower and upper unit cores are successively formed from an electric steel plate by punching so that the lower and upper unit cores are opposite to each other in orientation, a unit yoke of the lower unit core has an elongated end extending from a central line connecting a center of the tooth to a center of the core in a designated direction, and a unit yoke of the upper unit core has an elongated end extending from a central line connecting a center of the tooth to a center of the core in an opposite direction to the elongated end of the unit yoke of the lower unit core.    
     
     
         2 . The method for manufacturing a unit core of a motor as set forth in  claim 1 , wherein an angle from the central line connecting the center of the tooth to the center of the core has a value of θ r,max  determined by the following equation:  
       
         
           
             
               
                 
                   θ 
                   
                     r 
                     , 
                     max 
                   
                 
                 = 
                 
                   
                     θ 
                     sy 
                   
                   - 
                   
                     
                       sin 
                       
                         - 
                         1 
                       
                     
                      
                     
                       ( 
                       
                         
                           SOR 
                           * 
                           
                             sin 
                              
                             
                               ( 
                               
                                 
                                   θ 
                                   st 
                                 
                                 / 
                                 2 
                               
                               ) 
                             
                           
                         
                         
                           SIR 
                           + 
                           YL 
                         
                       
                       ) 
                     
                   
                 
               
               , 
             
           
           
           
               
           
         
         wherein, θ sy  is an angle between both terminal points of the unit yoke centering on the center of the core, SOR is an outer diameter of the core, θ st  is an angle between both terminals of an enlarged part of the tooth, and SIR is an inner diameter of the core, and YL is a radial width of the unit yoke.  
       
     
     
         3 . The method for manufacturing a unit core of a motor as set forth in  claim 1 , 
 wherein the terminal of the unit yoke on the non-extended side is longitudinally collinear with the terminal of the tooth on the non-extended side.    
     
     
         4 . The method for manufacturing a unit core of a motor as set forth in  claim 1 , 
 wherein a recess with a designated shape is formed on one end of the unit yoke, and a protrusion with a shape complementary with the recess is formed on the other end of the unit yoke.