METHOD FOR MAKING INTERMEDIATE BLANK FOR COMMUTATOR OF ELECTRIC MOTOR Russian patent published in 2002 - IPC

FIELD: plastic metal working, namely manufacture of commutators of electric motors. SUBSTANCE: method comprises steps of sizing blank and forming sleeve with supporting protrusions of commutator segments on its inner lateral surface by lengthwise pressing out of blank in die by means of punch; using punch having on its working end longitudinal grooves with cross section corresponding to that of supporting protrusions of commutator segments; forming on open portion of sleeve annular rim designed for shaping segment petal-like portions by lengthwise pressing out in die by means of punch with smooth lateral surface; removing bottom of sleeve and turning its ends; forming supporting protrusions of commutator segments with length equal to that of segments with allowance for end trimming after removing sleeve bottom; forming annular rim with wall height equal to length of segment portions with allowance for end trimming; after sizing annealing cylindrical blank. Annular rim is formed before forming sleeve with supporting protrusions of commutator segments in die closed at one side by means of punch whose smooth lateral surface is arranged on its working end. Sleeve with supporting protrusions of commutator segments on its inner lateral surface is formed by one pass with use of other punch in die closed at one side. EFFECT: enhanced reliability of intermediate blank. 4 dwg