PURPOSE: To improve and stabilize the caulking strength of the title core, by a method wherein projections are formed by employing a punch surface having a specified inclination.
CONSTITUTION: Pilot holes 11 are worked in a first process A, the shaft hole 12 of a rotor is worked in a second process B based on the reference of the pilot holes 11, slot holes 13 for casting aluminum are worked in a third process C and caulking protrusions 14 are worked in a fourth process D respectively and sequentially. The caulking protrusions 14 are worked employing a punch having the punch surface of 2∼15 degrees. The rotor, including the shaft hole 12, the slots 13 and the caulking protrusion 14, is punched out by a punch in next fifth process; further, teeth 16, becoming the magnetic poles of a stator, are formed in a 6th process F, thereafter, the caulking protrusion 17 is worked in a 7th process G by a punch, whose punch surface is worked so as to have 2∼15 degrees, while the pushing of the caulking protrusion 17 and the separation of the stator may be effected simultaneously in an 8th process.
MURO YOSHINARI
IIDA YOSHIAKI
