MANUFACTURE OF POLE FOR ROTOR OF MOTOR

PURPOSE:To increase the magnetic flux which is produced from a toothed part by pressing the raised part of the outer periphery of a sintered material to become poles, and forming a stepwise difference, thereby increasing the density of the outer periphery. CONSTITUTION:Powder is pressed between an upper punch and a lower punch, and a molded powder member 1 to form a gear shape having uniform thickness and both flat sides from the center over the outer periphery is molded. Then, the member 1 is sintered to form a sintered member. Further, a pole 1 is formed by pressing and hence coining it with a press shaping die. In this case, the toothed part 2 of the member 1 is pressed in a large compression ratio to reduce the side of the width and to increase the density of the toothed part 2. In this manner, the loss of the amount of magnetic flux can be reduced by a permanent magnet 3 which passes through the toothed part 2.