MANUFACTURE OF STATOR YOKE FOR MINIATURE MOTOR

摘要

PURPOSE:To obtain a stator having many pole pieces to the outside diameter of a motor and to attempt the improvement of torque as well by bending the external peripheral section of a flat plate to form cylindrical shape by drawing wherein many toothed pole pieces are formed by shearing work in the shaft direction hereinafter. CONSTITUTION:Triming and drawing are applied to ta flat plate composing of high-permeability material to form dished shape. Next, the plate is trottled to form cup shape. Further, drawing is followed to form cylindrical shape by gradually and inwardly swelling the central part at the bottom and a central end side is punched by trimming the external peripheral section. A semi-molded substance 10 is made by the above processes and many toothed pole pieces are formed at the internal peripheral section of the substance by a pillar-shaped punch 11 composing five petalled grooves at the cross section and a die 12. A toothed pole piece section is left and the remaining parts are cut off by closely contacting the punch 11 to the substance 10 and by gradually pressing and inserting the punch 11 to the substance 10. In this way, the length of stator pole pieces will be lengthened and torque will be improved.