Method of manufacturing a motor rotor

Abstract

A method of manufacturing a motor rotor includes a preparing step, a pre-heating step and a molding step. The preparing step includes preparing multiple silicon-steel sheets, a shaft, a mold and a molten copper liquid. The pre-heating step includes stacking the silicon-steel sheets and mounting the stacked silicon-steel sheets around the shaft and pre-heating the silicon-steel sheets to a specific temperature. The molding step includes mounting the silicon-steel sheets and the shaft into the mold, heating the silicon-steel sheets, the shaft and the mold, drawing air out of the mold to a vacuum status, injecting the molten copper liquid into the mold, sucking the molten copper liquid and filling up the mold with the molten copper liquid, cooling the mold to form a copper ring around the silicon-steel sheets, getting the shaft and the silicon-steel sheets with the copper ring out of the mold and separating the shaft from the silicon-steel sheets to form a motor rotor.

1 . A method of manufacturing a motor rotor comprising:
 a preparing step comprising:
 preparing multiple silicon-steel sheets and each silicon-steel sheet having a center, a shaft hole formed through the center of the silicon-steel sheet and multiple copper holes formed through the silicon-steel sheet at intervals around the shaft hole; 
 preparing a shaft with two free ends; 
 preparing a mold with a front end, a rear end, an injecting hole formed in the front end of the mold and a drafting hole formed in the rear end of the mold; and 
 preparing a molten copper liquid and keeping the temperature of the molten copper liquid at between 1200° C. and 1500° C.; 
   a pre-heating step comprising:
 stacking the silicon-steel sheets; 
 mounting the stacked silicon-steel sheets around the shaft by the shaft holes; and 
 pre-heating the silicon-steel sheets and the shaft for 10-30 minutes to a temperature between 200° C. and 500° C.; and 
   a molding step comprising:
 mounting the silicon-steel sheets and the shaft into the mold between the injecting hole and the drafting hole after heating to the temperature between 200° C. and 500° C.; 
 heating the silicon-steel sheets, the shaft and the mold for an hour to keep the temperature at between 200° C. and 500° C.; 
 drawing air out of the mold via the drafting hole to keep the mold at a vacuum status; 
 injecting the molten copper liquid into the mold via the injecting hole; 
 sucking the molten copper liquid and filling up the mold and the copper holes of the silicon-steel sheets with the molten copper liquid by the vacuum status of the mold; 
 cooling the mold after the molten copper liquid fills up the mold to form a copper ring around the silicon-steel sheets; 
 getting the shaft and the silicon-steel sheets with the copper ring out of the mold when the temperature of the mold is cooled down to 700° C. to 800° C.; 
 cooling the shaft and the silicon-steel sheets with the copper ring to room temperature; and 
 separating the shaft from the silicon-steel sheets to form the motor rotor. 
   
     
     
         2 - 5 . (canceled) 
     
     
         6 . The method of manufacturing a motor rotor as claimed in  claim 1 , wherein
 the preparing step comprises preparing a surface-treating device; and   the method of manufacturing a motor rotor comprises a forming step after the molding step, and the forming step comprises surfacing the copper ring by the surface-treating device after cooling the shaft and the silicon-steel sheets with the copper ring to room temperature.   
     
     
         7 . The method of manufacturing a motor rotor as claimed in  claim 6 , wherein
 the preparing step comprises preparing the shaft with two connecting holes respectively formed in the free ends of the shaft, two holding panels respectively abutting the free ends of the shaft and two fasteners respectively mounted through the holding panels and respectively connected to the connecting holes to hold the holding panels on the shaft;   the pre-heating step comprises holding the silicon-steel sheets on the shaft by the holding panels and the fasteners before pre-heating the silicon-steel sheets and the shaft; and   the forming step comprises separating the shaft from the silicon-steel sheets by loosening the fasteners to form the motor rotor.   
     
     
         8 . The method of manufacturing a motor rotor as claimed in  claim 7 , wherein the surface-treating device is a cutting machine to surface the copper ring. 
     
     
         9 . The method of manufacturing a motor rotor as claimed in  claim 7 , wherein the surface-treating device is a grinding machine to surface the copper ring. 
     
     
         10 - 11 . (canceled)