| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a ferrite magnet for DC motor, which is made to reduce cogging torques by contriving the structure of dies for forming magnetic field, while maintaining the present shape of the magnet. SOLUTION: The dies for forming the magnetic field of the ferrite magnet for DC motor has a die 10, an inner periphery-side punch 20 which comes into contact with the inner periphery side of a molded magnet body 1, and an outer periphery-side punch 30 which comes into contact with the outer periphery-side of the magnet body 1. The punches 20 and 30 are made of a magnetic material and a nonmagnetic material, in such a way that the nonmagnetic material comes into contact with the magnet body 1. In the punch 20, a ratio (h2/h1) of thickness h2 of the nonmagnetic material 22 facing the leg section of the magnet body 1 to a thickness h1 of the nonmagnetic material 22 at the center in the width direction is set at 3<=h2/h1<=10.
|
