METHOD OF MANUFACTURING YOKE OF ROTARY ELECTRIC MACHINE

PROBLEM TO BE SOLVED: To mold respective side pieces of a polygonal cylinder part of a yoke, including the polygonal cylinder part and an oval cylinder part, with good plane precision.SOLUTION: A yoke 4 is molded through the processes of: molding a base material 10 into a first intermediate body 11 in a bottomed cylinder shape; molding the first intermediate body 11 into a third intermediate body 13 having a hexagonal cylinder part 13b, an inclined cylinder part 13c, and a cylinder part 13d on the side of a bottom part 13a; and molding a fourth intermediate body 14 having a flat part corresponding part 14F which is long in a shaft core direction including the inclined cylinder part 13c and cylinder part 13d of the third intermediate body 13 as a flat plate corresponding part 14d. The flat part corresponding part 14F of the fourth intermediate body 14 to become a flat part F of the yoke 4 is molded using a die 15 having a projection piece 15h as a deformation stop part stopping an inner surface of the flat part corresponding part 14F from deforming on molding surfaces 15b, 15c opposed to the flat part corresponding part 14F.